FLUXNATION: Fused spike attention + step cache CUDA kernel for FLUX.1

Fused FP8 CUDA kernel for FLUX.1 SingleStreamBlock with spike attention
and step caching. Replaces ComfyUI's entire SingleStreamBlock forward pass
with a single torch.ops call — modulation, dual GEMMs, QKV, RoPE, attention,
gating and residual all fused. 30%+ faster than stock ComfyUI on RTX 4090.

Spike attention: block-sparse Triton kernel that scores attention blocks
by dot-product similarity and keeps only the top 45% after image structure
forms. Step caching replays cached attention output on alternating spike
steps for zero attention compute every other step.

Works with all 38 ComfyUI samplers at any step count.
FP16 ports included for 10-series, 20-series, and 30-series GPUs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
ULT7RA
2026-04-05 17:56:53 -06:00
co-authored by Copilot
commit 82bdde669f
33 changed files with 6579 additions and 0 deletions
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from __future__ import annotations
from typing import Dict, Optional, Tuple, Any
import torch
import torch.nn.functional as F
from . import FLUXSPIKEY as triton_backend
def attend(
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
*,
backend: str = "dense",
state: Optional[Dict[str, torch.Tensor]] = None,
neuromorph: Optional[Dict[str, Any]] = None,
) -> Tuple[torch.Tensor, Dict[str, Any]]:
if backend == "dense":
return _attend_dense(q, k, v)
elif backend == "spike":
neuromorph_cfg = neuromorph or {}
if triton_backend.has_triton():
return triton_backend.attend_spike_triton(
q, k, v,
tau=neuromorph_cfg.get("tau", 0.15),
leak=neuromorph_cfg.get("leak", 0.0),
event_cap_pct=neuromorph_cfg.get("event_cap_pct", 0.45),
state=state,
)
return _attend_spike(q, k, v, state=state, neuromorph=neuromorph_cfg)
else:
raise ValueError(f"Unknown backend: {backend}")
def _attend_dense(
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
) -> Tuple[torch.Tensor, Dict[str, Any]]:
scale = q.shape[-1] ** -0.5
scores = torch.matmul(q, k.transpose(-2, -1)) * scale
attn_weights = F.softmax(scores, dim=-1)
output = torch.matmul(attn_weights, v)
return output, {"backend": "dense", "attn_weights": attn_weights}
def _attend_spike(
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
*,
state: Optional[Dict[str, torch.Tensor]] = None,
neuromorph: Optional[Dict[str, Any]] = None,
) -> Tuple[torch.Tensor, Dict[str, Any]]:
cfg = neuromorph or {}
tau = cfg.get("tau", 0.15)
leak = cfg.get("leak", 0.0)
event_cap_pct = cfg.get("event_cap_pct", 0.45)
batch, heads, seq_len, head_dim = q.shape
scale = head_dim ** -0.5
z = torch.matmul(q, k.transpose(-2, -1)) * scale
z_max_per_row = z.max(dim=-1, keepdim=True)[0]
M_t = (z >= tau * z_max_per_row).float()
max_events_per_row = max(1, int(seq_len * event_cap_pct))
if max_events_per_row < seq_len:
_, topk_indices = torch.topk(z, k=max_events_per_row, dim=-1, sorted=False)
M_t_capped = torch.zeros_like(z)
M_t_capped.scatter_(-1, topk_indices, 1.0)
M_t = M_t * M_t_capped
if state is not None and "S_prev" in state and state["S_prev"].shape == M_t.shape:
S_t = leak * state["S_prev"] + M_t
else:
S_t = M_t
S_t_sum = S_t.sum(dim=-1, keepdim=True)
S_t_sum = torch.where(S_t_sum > 0, S_t_sum, torch.ones_like(S_t_sum))
attn_weights = (S_t / S_t_sum * M_t).to(v.dtype)
output = torch.matmul(attn_weights, v)
kept = M_t.sum().item()
total = batch * heads * seq_len * seq_len
flops_saved = 100.0 * (1.0 - kept / max(1, total))
return output, {
"S_prev": S_t.detach(),
"M_t": M_t,
"telemetry": {
"backend": "spike",
"kept_events_pct": 100.0 * kept / max(1, total),
"flops_saved_pct": flops_saved,
"tau": tau,
"leak": leak,
"event_cap_pct": event_cap_pct,
},
}
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#ifndef SINGLE_STREAM_BLOCK_FP16_H
#define SINGLE_STREAM_BLOCK_FP16_H
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <cublas_v2.h>
#include <cstdio>
#include <stdexcept>
#include <string>
namespace transformer {
constexpr int HIDDEN = 3072;
constexpr int HEADS = 24;
constexpr int HDIM = 128;
constexpr int FFDIM = 12288;
constexpr int MODDIM = 3 * HIDDEN;
constexpr int LIN1DIM = 3 * HIDDEN + FFDIM;
constexpr int LIN2DIM = HIDDEN + FFDIM;
constexpr float LN_EPS = 1e-6f;
constexpr float RMS_EPS = 1e-6f;
constexpr float ATT_SC = 0.0883883476f;
static int const kKernelThreads = 256;
static_assert((kKernelThreads % 32) == 0, "kKernelThreads must be a multiple of 32.");
#define CK(call) do { \
cudaError_t err__ = (call); \
if (err__ != cudaSuccess) { \
throw std::runtime_error(std::string("CUDA ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + cudaGetErrorString(err__)); \
} \
} while (0)
#define BK(call) do { \
cublasStatus_t st__ = (call); \
if (st__ != CUBLAS_STATUS_SUCCESS) { \
throw std::runtime_error(std::string("cuBLAS ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + std::to_string((int)st__)); \
} \
} while (0)
static inline size_t ssb_workspace_bytes(int batch, int seq) {
size_t rows = static_cast<size_t>(batch) * seq;
size_t b = static_cast<size_t>(batch);
size_t sz = 0;
#define ADDBUF(count, elem_size) \
sz = (sz + 255) & ~size_t(255); sz += (count) * (elem_size);
ADDBUF(b * HIDDEN, 2); // d_silu_
ADDBUF(b * MODDIM, 2); // d_mod_
ADDBUF(rows * HIDDEN, 2); // d_xmod_
ADDBUF(rows * LIN1DIM, 2); // d_l1o_
sz = (sz + 255) & ~size_t(255);
sz += 32ull << 20; // 32MB cuBLAS workspace
#undef ADDBUF
return sz;
}
class SSBEngine {
public:
SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size);
~SSBEngine();
void prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream = 0);
void finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream = 0);
int batch() const { return B_; }
int seq() const { return S_; }
private:
int B_;
int S_;
cublasHandle_t cub_;
void* workspace_;
size_t workspace_bytes_;
half* d_silu_;
half* d_mod_;
half* d_xmod_;
half* d_l1o_;
};
} // namespace transformer
#endif // SINGLE_STREAM_BLOCK_FP16_H
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@echo off
setlocal
REM FLUXNATION FP16 Build — 10-series (SM 61, Pascal)
REM Compatible with GTX 1060/1070/1080/1080 Ti
set "VSVARS=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
if not exist "%VSVARS%" (
echo [flux_ext] ERROR: VS 2022 vcvars64.bat not found
exit /b 1
)
call "%VSVARS%" || exit /b 1
set DISTUTILS_USE_SDK=1
echo [flux_ext] Building FLUXNATION FP16 for 10-series (SM 61)...
py -3.10 setup_ext.py install
if errorlevel 1 (
echo [flux_ext] Build FAILED
exit /b 1
)
echo [flux_ext] Build succeeded! flux_ext (FP16, SM 61) is now installed.
echo [flux_ext] Restart ComfyUI to use the new kernel.
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/*
* FLUXNATION_FP16.cu — PyTorch C++ extension for FLUXNATION (FP16-only)
*
* Wraps the FP16 SSBEngine as torch.ops custom operators.
* All weights converted to FP16 internally — no FP8, no CUTLASS.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include <torch/extension.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <unordered_map>
#include <memory>
#include <mutex>
using namespace transformer;
// =========================================================================
// Global engine cache — keyed by (device, batch, seq_len)
// =========================================================================
struct EngineEntry {
std::unique_ptr<SSBEngine> engine;
at::Tensor workspace;
};
static std::unordered_map<int64_t, EngineEntry> g_engine_cache;
static std::mutex g_engine_mutex;
static int64_t make_engine_key(int device, int batch, int seq) {
return (int64_t)device * 1000000000LL + (int64_t)batch * 1000000LL + seq;
}
static SSBEngine* get_or_create_engine(int batch, int seq, at::Device device) {
int dev_idx = device.index();
int64_t key = make_engine_key(dev_idx, batch, seq);
std::lock_guard<std::mutex> lock(g_engine_mutex);
auto it = g_engine_cache.find(key);
if (it != g_engine_cache.end()) {
return it->second.engine.get();
}
at::cuda::CUDAGuard guard(device);
size_t ws_bytes = ssb_workspace_bytes(batch, seq);
auto ws_tensor = at::empty({(int64_t)ws_bytes}, at::TensorOptions().dtype(at::kByte).device(device));
auto engine = std::make_unique<SSBEngine>(batch, seq, ws_tensor.data_ptr(), ws_bytes);
auto* ptr = engine.get();
EngineEntry entry;
entry.engine = std::move(engine);
entry.workspace = ws_tensor;
g_engine_cache[key] = std::move(entry);
fprintf(stderr, "[flux_ext FP16] Created engine B=%d S=%d ws=%.1fMB dev=%d\n",
batch, seq, ws_bytes / (1024.0 * 1024.0), dev_idx);
fflush(stderr);
return ptr;
}
// =========================================================================
// torch.ops implementation: ssb_prepare
//
// Same Python API as FP8 version — scale tensors are accepted but ignored.
// All weights converted to FP16 internally.
// =========================================================================
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, // [B, S, 3072] bf16
at::Tensor vec, // [B, 3072] or [B, 1, 3072] fp16
at::Tensor pe, // [S, 64, 2] fp16
at::Tensor mod_w, // weight (any dtype → converted to FP16)
at::Tensor mod_w_scale, // IGNORED in FP16 mode
at::Tensor mod_b, // fp16
at::Tensor l1w, // weight (any dtype → converted to FP16)
at::Tensor l1w_scale, // IGNORED in FP16 mode
at::Tensor l1b, // fp16
at::Tensor qns, // fp16
at::Tensor kns) // fp16
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Ensure correct dtypes — x stays BF16 (layernorm kernel reads it as BF16)
auto x_bf16 = x.to(at::kBFloat16).contiguous();
auto vec_fp16 = vec.dim() == 3 ? vec.squeeze(1).to(at::kHalf).contiguous()
: vec.to(at::kHalf).contiguous();
auto pe_fp16 = pe.to(at::kHalf).contiguous();
// Convert ALL weights to FP16 (no FP8 on this target)
auto mod_w_fp16 = mod_w.to(at::kHalf).contiguous();
auto mod_b_fp16 = mod_b.to(at::kHalf).contiguous();
auto l1w_fp16 = l1w.to(at::kHalf).contiguous();
auto l1b_fp16 = l1b.to(at::kHalf).contiguous();
auto qns_fp16 = qns.to(at::kHalf).contiguous();
auto kns_fp16 = kns.to(at::kHalf).contiguous();
// Allocate output tensors
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto q = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto k = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto v = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto mlp = at::empty({B, S, FFDIM}, opts_fp16);
auto gate = at::empty({B, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->prepare(
reinterpret_cast<const half*>(x_bf16.data_ptr()),
reinterpret_cast<const half*>(vec_fp16.data_ptr()),
reinterpret_cast<const half*>(pe_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_w_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_b_fp16.data_ptr()),
reinterpret_cast<const half*>(l1w_fp16.data_ptr()),
reinterpret_cast<const half*>(l1b_fp16.data_ptr()),
reinterpret_cast<const half*>(qns_fp16.data_ptr()),
reinterpret_cast<const half*>(kns_fp16.data_ptr()),
reinterpret_cast<half*>(q.data_ptr()),
reinterpret_cast<half*>(k.data_ptr()),
reinterpret_cast<half*>(v.data_ptr()),
reinterpret_cast<half*>(mlp.data_ptr()),
reinterpret_cast<half*>(gate.data_ptr()),
stream);
return std::make_tuple(q, k, v, mlp, gate);
}
// =========================================================================
// torch.ops implementation: ssb_finish
//
// FP16 path: converts residual (x) from BF16→FP16, runs all-FP16 engine,
// converts result back to BF16 for model compatibility.
// =========================================================================
at::Tensor ssb_finish_impl(
at::Tensor x, // [B, S, 3072] bf16 — original input for residual
at::Tensor attn, // [B, S, 3072] fp16 — attention output
at::Tensor mlp, // [B, S, 12288] fp16 — MLP intermediate (pre-GELU)
at::Tensor gate, // [B, 3072] fp16 — gate values
at::Tensor l2w, // weight (any dtype → converted to FP16)
at::Tensor l2w_scale, // IGNORED in FP16 mode
at::Tensor l2b) // fp16 — L2 bias
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Convert residual from BF16 to FP16 for the FP16 engine
auto x_fp16 = x.to(at::kHalf).contiguous();
auto attn_fp16 = attn.to(at::kHalf).contiguous();
auto mlp_c = mlp.contiguous();
auto gate_c = gate.contiguous();
auto l2w_fp16 = l2w.to(at::kHalf).contiguous();
auto l2b_fp16 = l2b.to(at::kHalf).contiguous();
// Result in FP16 (engine is all-FP16)
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto result_fp16 = at::empty({B, S, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->finish(
reinterpret_cast<const half*>(x_fp16.data_ptr()),
reinterpret_cast<const half*>(attn_fp16.data_ptr()),
reinterpret_cast<half*>(mlp_c.data_ptr()),
reinterpret_cast<const half*>(gate_c.data_ptr()),
reinterpret_cast<half*>(result_fp16.data_ptr()),
reinterpret_cast<const half*>(l2w_fp16.data_ptr()),
reinterpret_cast<const half*>(l2b_fp16.data_ptr()),
stream);
// Convert back to BF16 for model compatibility
return result_fp16.to(at::kBFloat16);
}
// =========================================================================
// Cleanup — destroys all cached engines
// =========================================================================
void ssb_cleanup_impl() {
std::lock_guard<std::mutex> lock(g_engine_mutex);
g_engine_cache.clear();
fprintf(stderr, "[flux_ext FP16] All engines destroyed\n");
fflush(stderr);
}
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/*
* FLUXPATCH_FP16.cpp — TORCH_LIBRARY registration for FLUXNATION (FP16-only)
*
* Registers ssb_prepare and ssb_finish as torch.ops.flux_ext.* custom ops.
* Identical API to the FP8 version — Python code doesn't change.
*/
#include <torch/extension.h>
#include <ATen/ATen.h>
// Forward declarations (in FLUXNATION_FP16.cu)
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, at::Tensor vec, at::Tensor pe,
at::Tensor mod_w, at::Tensor mod_w_scale, at::Tensor mod_b,
at::Tensor l1w, at::Tensor l1w_scale, at::Tensor l1b,
at::Tensor qns, at::Tensor kns);
at::Tensor ssb_finish_impl(
at::Tensor x, at::Tensor attn, at::Tensor mlp, at::Tensor gate,
at::Tensor l2w, at::Tensor l2w_scale, at::Tensor l2b);
void ssb_cleanup_impl();
TORCH_LIBRARY(flux_ext, m) {
m.def("ssb_prepare("
"Tensor x, Tensor vec, Tensor pe, "
"Tensor mod_w, Tensor mod_w_scale, Tensor mod_b, "
"Tensor l1w, Tensor l1w_scale, Tensor l1b, "
"Tensor qns, Tensor kns"
") -> (Tensor, Tensor, Tensor, Tensor, Tensor)");
m.def("ssb_finish("
"Tensor x, Tensor attn, Tensor mlp, Tensor gate, "
"Tensor l2w, Tensor l2w_scale, Tensor l2b"
") -> Tensor");
m.def("ssb_cleanup() -> ()");
}
TORCH_LIBRARY_IMPL(flux_ext, CUDA, m) {
m.impl("ssb_prepare", &ssb_prepare_impl);
m.impl("ssb_finish", &ssb_finish_impl);
m.impl("ssb_cleanup", &ssb_cleanup_impl);
}
PYBIND11_MODULE(flux_ext, m) {
m.doc() = "FLUXNATION FP16: Fused CUDA kernels for FLUX.1 SingleStreamBlock (no FP8)";
}
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/*
* flux_opt_fp16.cu — FP16-only SSBEngine for FLUXNATION
*
* Derived from flux_opt.cu. All FP8/CUTLASS code removed.
* Uses cuBLAS FP16 tensor-op GEMMs only.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <algorithm>
#include <cfloat>
#include <cmath>
#include <cstdlib>
namespace transformer {
// Vectorized load/store helpers — 128-bit (8 half elements) for max bandwidth
union VecHalf8 {
float4 f4;
half h[8];
};
union VecHalf4 {
float2 f2;
half h[4];
};
union VecHalf2 {
unsigned int u;
half h[2];
};
union VecBF16_4 {
float2 f2;
__nv_bfloat16 b[4];
};
union VecBF16_8 {
float4 f4;
__nv_bfloat16 b[8];
};
// FP16 GEMM via cuBLAS with tensor-op math
static inline void linear_gemm(cublasHandle_t cub,
int m,
int n,
int k,
const half* x,
const half* w_torch,
half* y)
{
const float alpha = 1.0f;
const float beta = 0.0f;
BK(cublasGemmEx(
cub,
CUBLAS_OP_T,
CUBLAS_OP_N,
n, m, k,
&alpha,
w_torch, CUDA_R_16F, k,
x, CUDA_R_16F, k,
&beta,
y, CUDA_R_16F, n,
CUBLAS_COMPUTE_32F_FAST_16F,
CUBLAS_GEMM_DEFAULT_TENSOR_OP));
}
__forceinline__ __device__ float warp_reduce_sum(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v += __shfl_down_sync(0xffffffff, v, offset);
}
return v;
}
__forceinline__ __device__ float warp_reduce_max(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v = fmaxf(v, __shfl_down_sync(0xffffffff, v, offset));
}
return v;
}
__forceinline__ __device__ float block_reduce_sum(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_sum(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : 0.0f;
x = warp_reduce_sum(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__forceinline__ __device__ float block_reduce_max(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_max(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : -FLT_MAX;
x = warp_reduce_max(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__global__ __launch_bounds__(256, 4)
void silu_kernel(const half* __restrict__ in,
half* __restrict__ out,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(in + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
v.h[j] = __float2half_rn(x / (1.0f + expf(-x)));
}
*reinterpret_cast<float4*>(out + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(in[i]);
out[i] = __float2half_rn(x / (1.0f + expf(-x)));
}
}
}
__global__ __launch_bounds__(256, 4)
void bias_add_kernel(half* __restrict__ out,
const half* __restrict__ bias,
int rows,
int cols)
{
int total = rows * cols;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 4;
if (base + 3 < total) {
int col = base % cols;
if (col + 3 < cols) {
VecHalf4 ov, bv;
ov.f2 = *reinterpret_cast<const float2*>(out + base);
bv.f2 = *reinterpret_cast<const float2*>(bias + col);
#pragma unroll
for (int j = 0; j < 4; j++)
ov.h[j] = __float2half_rn(__half2float(ov.h[j]) + __half2float(bv.h[j]));
*reinterpret_cast<float2*>(out + base) = ov.f2;
return;
}
}
for (int j = 0; j < 4 && base + j < total; j++) {
int idx = base + j;
int col = idx % cols;
float v = __half2float(out[idx]) + __half2float(bias[col]);
out[idx] = __float2half_rn(v);
}
}
// Input x is bf16 (model runs in bf16). Output is fp16. BF16→FP16 conversion is
// software-emulated on SM < 80 but is IO-bound so negligible overhead.
__global__ __launch_bounds__(256, 2)
void layernorm_mod_kernel(const __nv_bfloat16* __restrict__ x,
const half* __restrict__ mod,
half* __restrict__ out,
int seq)
{
int row = blockIdx.x;
int b = row / seq;
const __nv_bfloat16* x_row = x + static_cast<long long>(row) * HIDDEN;
half* out_row = out + static_cast<long long>(row) * HIDDEN;
const half* shift = mod + static_cast<long long>(b) * MODDIM;
const half* scale = shift + HIDDEN;
float sum = 0.0f;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 bv;
bv.f2 = *reinterpret_cast<const float2*>(x_row + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(bv.b[j]);
sum += v;
sq += v * v;
}
}
float mean = block_reduce_sum(sum) / HIDDEN;
float var = block_reduce_sum(sq) / HIDDEN - mean * mean;
float inv = rsqrtf(var + LN_EPS);
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 xv;
xv.f2 = *reinterpret_cast<const float2*>(x_row + i);
VecHalf4 sc_v, sh_v, ov;
sc_v.f2 = *reinterpret_cast<const float2*>(scale + i);
sh_v.f2 = *reinterpret_cast<const float2*>(shift + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(xv.b[j]);
float nrm = (v - mean) * inv;
ov.h[j] = __float2half_rn(nrm * (1.0f + __half2float(sc_v.h[j])) + __half2float(sh_v.h[j]));
}
*reinterpret_cast<float2*>(out_row + i) = ov.f2;
}
}
__global__ void split_qkv_kernel(const half* __restrict__ l1o,
half* __restrict__ q,
half* __restrict__ k,
half* __restrict__ v,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = seq * HIDDEN;
int batch_total = gridDim.y;
int linear = blockIdx.y * total + idx;
int max_linear = batch_total * total;
if (linear >= max_linear) return;
int token = linear / HIDDEN;
int h = linear % HIDDEN;
int b = token / seq;
int s = token % seq;
int head = h / HDIM;
int d = h % HDIM;
long long base_l1 = static_cast<long long>(token) * LIN1DIM;
long long dst = (((static_cast<long long>(b) * HEADS + head) * seq) + s) * HDIM + d;
q[dst] = l1o[base_l1 + h];
k[dst] = l1o[base_l1 + HIDDEN + h];
v[dst] = l1o[base_l1 + 2 * HIDDEN + h];
}
__global__ __launch_bounds__(256, 6)
void copy_mlp_kernel(const half* __restrict__ l1o,
half* __restrict__ mlp,
int rows)
{
int total = rows * FFDIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / FFDIM;
int col = base % FFDIM;
if (col + 7 < FFDIM) {
float4 v = *reinterpret_cast<const float4*>(l1o + static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col);
*reinterpret_cast<float4*>(mlp + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / FFDIM;
int col = idx % FFDIM;
mlp[idx] = l1o[static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col];
}
}
__global__ __launch_bounds__(256, 6)
void extract_gate_kernel(const half* __restrict__ mod,
half* __restrict__ gate,
int batch)
{
int total = batch * HIDDEN;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int b = base / HIDDEN;
int h = base % HIDDEN;
if (h + 7 < HIDDEN) {
float4 v = *reinterpret_cast<const float4*>(mod + static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h);
*reinterpret_cast<float4*>(gate + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int b = idx / HIDDEN;
int h = idx % HIDDEN;
gate[idx] = mod[static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h];
}
}
__global__ __launch_bounds__(256, 2)
void rmsnorm_scale_kernel(half* __restrict__ data,
const half* __restrict__ scale)
{
int row = blockIdx.x;
half* row_ptr = data + static_cast<long long>(row) * HDIM;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float val = __half2float(v.h[j]);
sq += val * val;
}
}
float inv = rsqrtf(block_reduce_sum(sq) / HDIM + RMS_EPS);
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v, sc;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
sc.f2 = *reinterpret_cast<const float2*>(scale + i);
#pragma unroll
for (int j = 0; j < 4; j++)
v.h[j] = __float2half_rn(__half2float(v.h[j]) * inv * __half2float(sc.h[j]));
*reinterpret_cast<float2*>(row_ptr + i) = v.f2;
}
}
__global__ __launch_bounds__(256, 4)
void rope_kernel(half* __restrict__ q,
half* __restrict__ k,
const half* __restrict__ pe,
int batch,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = batch * HEADS * seq * (HDIM / 2);
if (idx >= total) {
return;
}
int pair = idx % (HDIM / 2);
int t0 = idx / (HDIM / 2);
int s = t0 % seq;
int t1 = t0 / seq;
int h = t1 % HEADS;
int b = t1 / HEADS;
long long base = (((static_cast<long long>(b) * HEADS + h) * seq) + s) * HDIM + 2 * pair;
long long pe_off = (static_cast<long long>(s) * (HDIM / 2) + pair) * 2;
VecHalf2 pe_v;
pe_v.u = *reinterpret_cast<const unsigned int*>(pe + pe_off);
float c = __half2float(pe_v.h[0]);
float sn = __half2float(pe_v.h[1]);
VecHalf2 qv;
qv.u = *reinterpret_cast<const unsigned int*>(q + base);
float q0 = __half2float(qv.h[0]);
float q1 = __half2float(qv.h[1]);
qv.h[0] = __float2half_rn(q0 * c - q1 * sn);
qv.h[1] = __float2half_rn(q0 * sn + q1 * c);
*reinterpret_cast<unsigned int*>(q + base) = qv.u;
VecHalf2 kv;
kv.u = *reinterpret_cast<const unsigned int*>(k + base);
float k0 = __half2float(kv.h[0]);
float k1 = __half2float(kv.h[1]);
kv.h[0] = __float2half_rn(k0 * c - k1 * sn);
kv.h[1] = __float2half_rn(k0 * sn + k1 * c);
*reinterpret_cast<unsigned int*>(k + base) = kv.u;
}
__global__ __launch_bounds__(256, 4)
void gelu_tanh_kernel(half* __restrict__ data,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(data + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
float x3 = x * x * x;
v.h[j] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
*reinterpret_cast<float4*>(data + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(data[i]);
float x3 = x * x * x;
data[i] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
}
}
__global__ __launch_bounds__(256, 6)
void concat_final_kernel(const half* __restrict__ attn,
const half* __restrict__ mlp,
half* __restrict__ out,
int rows)
{
int total = rows * LIN2DIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / LIN2DIM;
int col = base % LIN2DIM;
if (col + 7 < LIN2DIM) {
float4 v;
if (col + 7 < HIDDEN) {
v = *reinterpret_cast<const float4*>(attn + static_cast<long long>(row) * HIDDEN + col);
} else if (col >= HIDDEN) {
v = *reinterpret_cast<const float4*>(mlp + static_cast<long long>(row) * FFDIM + (col - HIDDEN));
} else {
VecHalf8 vh;
#pragma unroll
for (int j = 0; j < 8; j++) {
int c = col + j;
if (c < HIDDEN)
vh.h[j] = attn[static_cast<long long>(row) * HIDDEN + c];
else
vh.h[j] = mlp[static_cast<long long>(row) * FFDIM + (c - HIDDEN)];
}
v = vh.f4;
}
*reinterpret_cast<float4*>(out + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / LIN2DIM;
int col = idx % LIN2DIM;
if (col < HIDDEN)
out[idx] = attn[static_cast<long long>(row) * HIDDEN + col];
else
out[idx] = mlp[static_cast<long long>(row) * FFDIM + (col - HIDDEN)];
}
}
__global__ void gate_residual_kernel(const half* __restrict__ residual,
const half* __restrict__ gate,
half* __restrict__ out,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = gridDim.y * seq * HIDDEN;
int linear = blockIdx.y * (seq * HIDDEN) + idx;
if (linear >= total) {
return;
}
int h = linear % HIDDEN;
int token = linear / HIDDEN;
int b = token / seq;
float gate_v = __half2float(gate[static_cast<long long>(b) * HIDDEN + h]);
float res = __half2float(residual[linear]);
float v = __half2float(out[linear]);
out[linear] = __float2half_rn(res + gate_v * v);
}
// =========================================================================
// SSBEngine — FP16-only (no FP8, no CUTLASS)
// =========================================================================
SSBEngine::SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size)
: B_(batch),
S_(seq),
cub_(nullptr),
workspace_(nullptr),
workspace_bytes_(0),
d_silu_(nullptr),
d_mod_(nullptr),
d_xmod_(nullptr),
d_l1o_(nullptr)
{
BK(cublasCreate(&cub_));
BK(cublasSetMathMode(cub_, CUBLAS_TENSOR_OP_MATH));
size_t min_needed = ssb_workspace_bytes(B_, S_);
if (workspace_buf_size < min_needed) {
throw std::runtime_error("Workspace buffer too small: need " +
std::to_string(min_needed) + " got " + std::to_string(workspace_buf_size));
}
char* p = static_cast<char*>(workspace_buf);
size_t off = 0;
size_t rows = static_cast<size_t>(B_) * S_;
#define CARVE(ptr, type, count) \
off = (off + 255) & ~size_t(255); \
ptr = reinterpret_cast<type*>(p + off); \
off += static_cast<size_t>(count) * sizeof(type);
CARVE(d_silu_, half, B_ * HIDDEN)
CARVE(d_mod_, half, static_cast<size_t>(B_) * MODDIM)
CARVE(d_xmod_, half, rows * HIDDEN)
CARVE(d_l1o_, half, rows * LIN1DIM)
#undef CARVE
off = (off + 255) & ~size_t(255);
workspace_ = p + off;
workspace_bytes_ = workspace_buf_size - off;
}
SSBEngine::~SSBEngine()
{
if (cub_) cublasDestroy(cub_);
}
void SSBEngine::prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// SiLU on vec
silu_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_vec, d_silu_, B_ * HIDDEN);
// Modulation GEMM: FP16→FP16
linear_gemm(cub_, B_, MODDIM, HIDDEN, d_silu_, mod_w, d_mod_);
int out_n = B_ * MODDIM;
bias_add_kernel<<<(out_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_mod_, mod_b, B_, MODDIM);
// LayerNorm + Modulation (reads x as BF16, outputs FP16)
layernorm_mod_kernel<<<rows, threads, 0, stream>>>(reinterpret_cast<const __nv_bfloat16*>(d_x), d_mod_, d_xmod_, S_);
// Linear1 GEMM: FP16→FP16
linear_gemm(cub_, rows, LIN1DIM, HIDDEN, d_xmod_, l1w, d_l1o_);
int l1_n = rows * LIN1DIM;
bias_add_kernel<<<(l1_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_l1o_, l1b, rows, LIN1DIM);
// Split Q/K/V from Linear1 output
dim3 split_grid((S_ * HIDDEN + threads - 1) / threads, B_);
split_qkv_kernel<<<split_grid, threads, 0, stream>>>(d_l1o_, d_q, d_k, d_v, S_);
// Copy MLP portion
copy_mlp_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_l1o_, d_mlp, rows);
// Extract gate from modulation output
extract_gate_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mod_, d_gate, B_);
// RMSNorm + scale on Q and K
int qk_rows = B_ * HEADS * S_;
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_q, qns);
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_k, kns);
// RoPE
int rope_total = B_ * HEADS * S_ * (HDIM / 2);
rope_kernel<<<(rope_total + threads - 1) / threads, threads, 0, stream>>>(d_q, d_k, d_pe, B_, S_);
CK(cudaGetLastError());
}
void SSBEngine::finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// GELU on MLP
gelu_tanh_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mlp, rows * FFDIM);
// Concat attention + MLP → d_l1o_ (reused as temp)
concat_final_kernel<<<(rows * LIN2DIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_attn, d_mlp, d_l1o_, rows);
// Linear2 GEMM: FP16→FP16
linear_gemm(cub_, rows, HIDDEN, LIN2DIM, d_l1o_, l2w, d_out);
// Bias add
int out_blocks = (rows * HIDDEN + threads * 4 - 1) / (threads * 4);
bias_add_kernel<<<out_blocks, threads, 0, stream>>>(d_out, l2b, rows, HIDDEN);
// Gate + residual: out = x + gate * out
dim3 gate_grid((S_ * HIDDEN + threads - 1) / threads, B_);
gate_residual_kernel<<<gate_grid, threads, 0, stream>>>(d_x, d_gate, d_out, S_);
CK(cudaGetLastError());
}
} // namespace transformer
+53
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@@ -0,0 +1,53 @@
"""
Build script for flux_ext FP16 PyTorch C++/CUDA extension — 10-series (SM 61, Pascal).
Usage:
py -3.10 setup_ext.py install
Compiles the FP16-only FLUXNATION kernel (no FP8, no CUTLASS).
Compatible with GTX 1060, 1070, 1080, 1080 Ti.
"""
import os
os.environ["CUDA_HOME"] = r"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.8"
os.environ["CUDA_PATH"] = os.environ["CUDA_HOME"]
from setuptools import setup
from torch.utils.cpp_extension import CUDAExtension, BuildExtension
ROOT = os.path.dirname(os.path.abspath(__file__))
setup(
name="flux_ext",
ext_modules=[
CUDAExtension(
name="flux_ext",
sources=[
os.path.join(ROOT, "csrc", "FLUXPATCH_FP16.cpp"),
os.path.join(ROOT, "csrc", "FLUXNATION_FP16.cu"),
os.path.join(ROOT, "flux_opt_fp16.cu"),
],
include_dirs=[
ROOT, # SINGLE_STREAM_BLOCK_FP16.H
],
extra_compile_args={
"cxx": ["/O2", "/std:c++17", "/EHsc", "/MD"],
"nvcc": [
"-O3",
"-std=c++17",
"-arch=sm_61",
"-DFLUX_TORCH_EXT=1",
"--allow-unsupported-compiler",
"-diag-suppress=20013",
"-diag-suppress=20015",
"-Xcompiler", "/MD",
"-Xcompiler", "/EHsc",
"-Xcompiler", "/Zc:preprocessor",
],
},
libraries=["cublas"],
)
],
cmdclass={"build_ext": BuildExtension},
)
@@ -0,0 +1,106 @@
#ifndef SINGLE_STREAM_BLOCK_FP16_H
#define SINGLE_STREAM_BLOCK_FP16_H
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <cublas_v2.h>
#include <cstdio>
#include <stdexcept>
#include <string>
namespace transformer {
constexpr int HIDDEN = 3072;
constexpr int HEADS = 24;
constexpr int HDIM = 128;
constexpr int FFDIM = 12288;
constexpr int MODDIM = 3 * HIDDEN;
constexpr int LIN1DIM = 3 * HIDDEN + FFDIM;
constexpr int LIN2DIM = HIDDEN + FFDIM;
constexpr float LN_EPS = 1e-6f;
constexpr float RMS_EPS = 1e-6f;
constexpr float ATT_SC = 0.0883883476f;
static int const kKernelThreads = 256;
static_assert((kKernelThreads % 32) == 0, "kKernelThreads must be a multiple of 32.");
#define CK(call) do { \
cudaError_t err__ = (call); \
if (err__ != cudaSuccess) { \
throw std::runtime_error(std::string("CUDA ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + cudaGetErrorString(err__)); \
} \
} while (0)
#define BK(call) do { \
cublasStatus_t st__ = (call); \
if (st__ != CUBLAS_STATUS_SUCCESS) { \
throw std::runtime_error(std::string("cuBLAS ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + std::to_string((int)st__)); \
} \
} while (0)
static inline size_t ssb_workspace_bytes(int batch, int seq) {
size_t rows = static_cast<size_t>(batch) * seq;
size_t b = static_cast<size_t>(batch);
size_t sz = 0;
#define ADDBUF(count, elem_size) \
sz = (sz + 255) & ~size_t(255); sz += (count) * (elem_size);
ADDBUF(b * HIDDEN, 2); // d_silu_
ADDBUF(b * MODDIM, 2); // d_mod_
ADDBUF(rows * HIDDEN, 2); // d_xmod_
ADDBUF(rows * LIN1DIM, 2); // d_l1o_
sz = (sz + 255) & ~size_t(255);
sz += 32ull << 20; // 32MB cuBLAS workspace
#undef ADDBUF
return sz;
}
class SSBEngine {
public:
SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size);
~SSBEngine();
void prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream = 0);
void finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream = 0);
int batch() const { return B_; }
int seq() const { return S_; }
private:
int B_;
int S_;
cublasHandle_t cub_;
void* workspace_;
size_t workspace_bytes_;
half* d_silu_;
half* d_mod_;
half* d_xmod_;
half* d_l1o_;
};
} // namespace transformer
#endif // SINGLE_STREAM_BLOCK_FP16_H
+25
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@echo off
setlocal
REM FLUXNATION FP16 Build — 20-series (SM 75, Turing)
REM Compatible with RTX 2060/2070/2080/2080 Ti
set "VSVARS=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
if not exist "%VSVARS%" (
echo [flux_ext] ERROR: VS 2022 vcvars64.bat not found
exit /b 1
)
call "%VSVARS%" || exit /b 1
set DISTUTILS_USE_SDK=1
echo [flux_ext] Building FLUXNATION FP16 for 20-series (SM 75)...
py -3.10 setup_ext.py install
if errorlevel 1 (
echo [flux_ext] Build FAILED
exit /b 1
)
echo [flux_ext] Build succeeded! flux_ext (FP16, SM 75) is now installed.
echo [flux_ext] Restart ComfyUI to use the new kernel.
+198
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@@ -0,0 +1,198 @@
/*
* FLUXNATION_FP16.cu — PyTorch C++ extension for FLUXNATION (FP16-only)
*
* Wraps the FP16 SSBEngine as torch.ops custom operators.
* All weights converted to FP16 internally — no FP8, no CUTLASS.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include <torch/extension.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <unordered_map>
#include <memory>
#include <mutex>
using namespace transformer;
// =========================================================================
// Global engine cache — keyed by (device, batch, seq_len)
// =========================================================================
struct EngineEntry {
std::unique_ptr<SSBEngine> engine;
at::Tensor workspace;
};
static std::unordered_map<int64_t, EngineEntry> g_engine_cache;
static std::mutex g_engine_mutex;
static int64_t make_engine_key(int device, int batch, int seq) {
return (int64_t)device * 1000000000LL + (int64_t)batch * 1000000LL + seq;
}
static SSBEngine* get_or_create_engine(int batch, int seq, at::Device device) {
int dev_idx = device.index();
int64_t key = make_engine_key(dev_idx, batch, seq);
std::lock_guard<std::mutex> lock(g_engine_mutex);
auto it = g_engine_cache.find(key);
if (it != g_engine_cache.end()) {
return it->second.engine.get();
}
at::cuda::CUDAGuard guard(device);
size_t ws_bytes = ssb_workspace_bytes(batch, seq);
auto ws_tensor = at::empty({(int64_t)ws_bytes}, at::TensorOptions().dtype(at::kByte).device(device));
auto engine = std::make_unique<SSBEngine>(batch, seq, ws_tensor.data_ptr(), ws_bytes);
auto* ptr = engine.get();
EngineEntry entry;
entry.engine = std::move(engine);
entry.workspace = ws_tensor;
g_engine_cache[key] = std::move(entry);
fprintf(stderr, "[flux_ext FP16] Created engine B=%d S=%d ws=%.1fMB dev=%d\n",
batch, seq, ws_bytes / (1024.0 * 1024.0), dev_idx);
fflush(stderr);
return ptr;
}
// =========================================================================
// torch.ops implementation: ssb_prepare
//
// Same Python API as FP8 version — scale tensors are accepted but ignored.
// All weights converted to FP16 internally.
// =========================================================================
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, // [B, S, 3072] bf16
at::Tensor vec, // [B, 3072] or [B, 1, 3072] fp16
at::Tensor pe, // [S, 64, 2] fp16
at::Tensor mod_w, // weight (any dtype → converted to FP16)
at::Tensor mod_w_scale, // IGNORED in FP16 mode
at::Tensor mod_b, // fp16
at::Tensor l1w, // weight (any dtype → converted to FP16)
at::Tensor l1w_scale, // IGNORED in FP16 mode
at::Tensor l1b, // fp16
at::Tensor qns, // fp16
at::Tensor kns) // fp16
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Ensure correct dtypes — x stays BF16 (layernorm kernel reads it as BF16)
auto x_bf16 = x.to(at::kBFloat16).contiguous();
auto vec_fp16 = vec.dim() == 3 ? vec.squeeze(1).to(at::kHalf).contiguous()
: vec.to(at::kHalf).contiguous();
auto pe_fp16 = pe.to(at::kHalf).contiguous();
// Convert ALL weights to FP16 (no FP8 on this target)
auto mod_w_fp16 = mod_w.to(at::kHalf).contiguous();
auto mod_b_fp16 = mod_b.to(at::kHalf).contiguous();
auto l1w_fp16 = l1w.to(at::kHalf).contiguous();
auto l1b_fp16 = l1b.to(at::kHalf).contiguous();
auto qns_fp16 = qns.to(at::kHalf).contiguous();
auto kns_fp16 = kns.to(at::kHalf).contiguous();
// Allocate output tensors
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto q = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto k = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto v = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto mlp = at::empty({B, S, FFDIM}, opts_fp16);
auto gate = at::empty({B, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->prepare(
reinterpret_cast<const half*>(x_bf16.data_ptr()),
reinterpret_cast<const half*>(vec_fp16.data_ptr()),
reinterpret_cast<const half*>(pe_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_w_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_b_fp16.data_ptr()),
reinterpret_cast<const half*>(l1w_fp16.data_ptr()),
reinterpret_cast<const half*>(l1b_fp16.data_ptr()),
reinterpret_cast<const half*>(qns_fp16.data_ptr()),
reinterpret_cast<const half*>(kns_fp16.data_ptr()),
reinterpret_cast<half*>(q.data_ptr()),
reinterpret_cast<half*>(k.data_ptr()),
reinterpret_cast<half*>(v.data_ptr()),
reinterpret_cast<half*>(mlp.data_ptr()),
reinterpret_cast<half*>(gate.data_ptr()),
stream);
return std::make_tuple(q, k, v, mlp, gate);
}
// =========================================================================
// torch.ops implementation: ssb_finish
//
// FP16 path: converts residual (x) from BF16→FP16, runs all-FP16 engine,
// converts result back to BF16 for model compatibility.
// =========================================================================
at::Tensor ssb_finish_impl(
at::Tensor x, // [B, S, 3072] bf16 — original input for residual
at::Tensor attn, // [B, S, 3072] fp16 — attention output
at::Tensor mlp, // [B, S, 12288] fp16 — MLP intermediate (pre-GELU)
at::Tensor gate, // [B, 3072] fp16 — gate values
at::Tensor l2w, // weight (any dtype → converted to FP16)
at::Tensor l2w_scale, // IGNORED in FP16 mode
at::Tensor l2b) // fp16 — L2 bias
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Convert residual from BF16 to FP16 for the FP16 engine
auto x_fp16 = x.to(at::kHalf).contiguous();
auto attn_fp16 = attn.to(at::kHalf).contiguous();
auto mlp_c = mlp.contiguous();
auto gate_c = gate.contiguous();
auto l2w_fp16 = l2w.to(at::kHalf).contiguous();
auto l2b_fp16 = l2b.to(at::kHalf).contiguous();
// Result in FP16 (engine is all-FP16)
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto result_fp16 = at::empty({B, S, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->finish(
reinterpret_cast<const half*>(x_fp16.data_ptr()),
reinterpret_cast<const half*>(attn_fp16.data_ptr()),
reinterpret_cast<half*>(mlp_c.data_ptr()),
reinterpret_cast<const half*>(gate_c.data_ptr()),
reinterpret_cast<half*>(result_fp16.data_ptr()),
reinterpret_cast<const half*>(l2w_fp16.data_ptr()),
reinterpret_cast<const half*>(l2b_fp16.data_ptr()),
stream);
// Convert back to BF16 for model compatibility
return result_fp16.to(at::kBFloat16);
}
// =========================================================================
// Cleanup — destroys all cached engines
// =========================================================================
void ssb_cleanup_impl() {
std::lock_guard<std::mutex> lock(g_engine_mutex);
g_engine_cache.clear();
fprintf(stderr, "[flux_ext FP16] All engines destroyed\n");
fflush(stderr);
}
@@ -0,0 +1,49 @@
/*
* FLUXPATCH_FP16.cpp — TORCH_LIBRARY registration for FLUXNATION (FP16-only)
*
* Registers ssb_prepare and ssb_finish as torch.ops.flux_ext.* custom ops.
* Identical API to the FP8 version — Python code doesn't change.
*/
#include <torch/extension.h>
#include <ATen/ATen.h>
// Forward declarations (in FLUXNATION_FP16.cu)
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, at::Tensor vec, at::Tensor pe,
at::Tensor mod_w, at::Tensor mod_w_scale, at::Tensor mod_b,
at::Tensor l1w, at::Tensor l1w_scale, at::Tensor l1b,
at::Tensor qns, at::Tensor kns);
at::Tensor ssb_finish_impl(
at::Tensor x, at::Tensor attn, at::Tensor mlp, at::Tensor gate,
at::Tensor l2w, at::Tensor l2w_scale, at::Tensor l2b);
void ssb_cleanup_impl();
TORCH_LIBRARY(flux_ext, m) {
m.def("ssb_prepare("
"Tensor x, Tensor vec, Tensor pe, "
"Tensor mod_w, Tensor mod_w_scale, Tensor mod_b, "
"Tensor l1w, Tensor l1w_scale, Tensor l1b, "
"Tensor qns, Tensor kns"
") -> (Tensor, Tensor, Tensor, Tensor, Tensor)");
m.def("ssb_finish("
"Tensor x, Tensor attn, Tensor mlp, Tensor gate, "
"Tensor l2w, Tensor l2w_scale, Tensor l2b"
") -> Tensor");
m.def("ssb_cleanup() -> ()");
}
TORCH_LIBRARY_IMPL(flux_ext, CUDA, m) {
m.impl("ssb_prepare", &ssb_prepare_impl);
m.impl("ssb_finish", &ssb_finish_impl);
m.impl("ssb_cleanup", &ssb_cleanup_impl);
}
PYBIND11_MODULE(flux_ext, m) {
m.doc() = "FLUXNATION FP16: Fused CUDA kernels for FLUX.1 SingleStreamBlock (no FP8)";
}
+611
View File
@@ -0,0 +1,611 @@
/*
* flux_opt_fp16.cu — FP16-only SSBEngine for FLUXNATION
*
* Derived from flux_opt.cu. All FP8/CUTLASS code removed.
* Uses cuBLAS FP16 tensor-op GEMMs only.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <algorithm>
#include <cfloat>
#include <cmath>
#include <cstdlib>
namespace transformer {
// Vectorized load/store helpers — 128-bit (8 half elements) for max bandwidth
union VecHalf8 {
float4 f4;
half h[8];
};
union VecHalf4 {
float2 f2;
half h[4];
};
union VecHalf2 {
unsigned int u;
half h[2];
};
union VecBF16_4 {
float2 f2;
__nv_bfloat16 b[4];
};
union VecBF16_8 {
float4 f4;
__nv_bfloat16 b[8];
};
// FP16 GEMM via cuBLAS with tensor-op math
static inline void linear_gemm(cublasHandle_t cub,
int m,
int n,
int k,
const half* x,
const half* w_torch,
half* y)
{
const float alpha = 1.0f;
const float beta = 0.0f;
BK(cublasGemmEx(
cub,
CUBLAS_OP_T,
CUBLAS_OP_N,
n, m, k,
&alpha,
w_torch, CUDA_R_16F, k,
x, CUDA_R_16F, k,
&beta,
y, CUDA_R_16F, n,
CUBLAS_COMPUTE_32F_FAST_16F,
CUBLAS_GEMM_DEFAULT_TENSOR_OP));
}
__forceinline__ __device__ float warp_reduce_sum(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v += __shfl_down_sync(0xffffffff, v, offset);
}
return v;
}
__forceinline__ __device__ float warp_reduce_max(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v = fmaxf(v, __shfl_down_sync(0xffffffff, v, offset));
}
return v;
}
__forceinline__ __device__ float block_reduce_sum(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_sum(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : 0.0f;
x = warp_reduce_sum(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__forceinline__ __device__ float block_reduce_max(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_max(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : -FLT_MAX;
x = warp_reduce_max(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__global__ __launch_bounds__(256, 4)
void silu_kernel(const half* __restrict__ in,
half* __restrict__ out,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(in + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
v.h[j] = __float2half_rn(x / (1.0f + expf(-x)));
}
*reinterpret_cast<float4*>(out + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(in[i]);
out[i] = __float2half_rn(x / (1.0f + expf(-x)));
}
}
}
__global__ __launch_bounds__(256, 4)
void bias_add_kernel(half* __restrict__ out,
const half* __restrict__ bias,
int rows,
int cols)
{
int total = rows * cols;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 4;
if (base + 3 < total) {
int col = base % cols;
if (col + 3 < cols) {
VecHalf4 ov, bv;
ov.f2 = *reinterpret_cast<const float2*>(out + base);
bv.f2 = *reinterpret_cast<const float2*>(bias + col);
#pragma unroll
for (int j = 0; j < 4; j++)
ov.h[j] = __float2half_rn(__half2float(ov.h[j]) + __half2float(bv.h[j]));
*reinterpret_cast<float2*>(out + base) = ov.f2;
return;
}
}
for (int j = 0; j < 4 && base + j < total; j++) {
int idx = base + j;
int col = idx % cols;
float v = __half2float(out[idx]) + __half2float(bias[col]);
out[idx] = __float2half_rn(v);
}
}
// Input x is bf16 (model runs in bf16). Output is fp16. BF16→FP16 conversion is
// software-emulated on SM < 80 but is IO-bound so negligible overhead.
__global__ __launch_bounds__(256, 2)
void layernorm_mod_kernel(const __nv_bfloat16* __restrict__ x,
const half* __restrict__ mod,
half* __restrict__ out,
int seq)
{
int row = blockIdx.x;
int b = row / seq;
const __nv_bfloat16* x_row = x + static_cast<long long>(row) * HIDDEN;
half* out_row = out + static_cast<long long>(row) * HIDDEN;
const half* shift = mod + static_cast<long long>(b) * MODDIM;
const half* scale = shift + HIDDEN;
float sum = 0.0f;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 bv;
bv.f2 = *reinterpret_cast<const float2*>(x_row + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(bv.b[j]);
sum += v;
sq += v * v;
}
}
float mean = block_reduce_sum(sum) / HIDDEN;
float var = block_reduce_sum(sq) / HIDDEN - mean * mean;
float inv = rsqrtf(var + LN_EPS);
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 xv;
xv.f2 = *reinterpret_cast<const float2*>(x_row + i);
VecHalf4 sc_v, sh_v, ov;
sc_v.f2 = *reinterpret_cast<const float2*>(scale + i);
sh_v.f2 = *reinterpret_cast<const float2*>(shift + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(xv.b[j]);
float nrm = (v - mean) * inv;
ov.h[j] = __float2half_rn(nrm * (1.0f + __half2float(sc_v.h[j])) + __half2float(sh_v.h[j]));
}
*reinterpret_cast<float2*>(out_row + i) = ov.f2;
}
}
__global__ void split_qkv_kernel(const half* __restrict__ l1o,
half* __restrict__ q,
half* __restrict__ k,
half* __restrict__ v,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = seq * HIDDEN;
int batch_total = gridDim.y;
int linear = blockIdx.y * total + idx;
int max_linear = batch_total * total;
if (linear >= max_linear) return;
int token = linear / HIDDEN;
int h = linear % HIDDEN;
int b = token / seq;
int s = token % seq;
int head = h / HDIM;
int d = h % HDIM;
long long base_l1 = static_cast<long long>(token) * LIN1DIM;
long long dst = (((static_cast<long long>(b) * HEADS + head) * seq) + s) * HDIM + d;
q[dst] = l1o[base_l1 + h];
k[dst] = l1o[base_l1 + HIDDEN + h];
v[dst] = l1o[base_l1 + 2 * HIDDEN + h];
}
__global__ __launch_bounds__(256, 6)
void copy_mlp_kernel(const half* __restrict__ l1o,
half* __restrict__ mlp,
int rows)
{
int total = rows * FFDIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / FFDIM;
int col = base % FFDIM;
if (col + 7 < FFDIM) {
float4 v = *reinterpret_cast<const float4*>(l1o + static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col);
*reinterpret_cast<float4*>(mlp + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / FFDIM;
int col = idx % FFDIM;
mlp[idx] = l1o[static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col];
}
}
__global__ __launch_bounds__(256, 6)
void extract_gate_kernel(const half* __restrict__ mod,
half* __restrict__ gate,
int batch)
{
int total = batch * HIDDEN;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int b = base / HIDDEN;
int h = base % HIDDEN;
if (h + 7 < HIDDEN) {
float4 v = *reinterpret_cast<const float4*>(mod + static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h);
*reinterpret_cast<float4*>(gate + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int b = idx / HIDDEN;
int h = idx % HIDDEN;
gate[idx] = mod[static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h];
}
}
__global__ __launch_bounds__(256, 2)
void rmsnorm_scale_kernel(half* __restrict__ data,
const half* __restrict__ scale)
{
int row = blockIdx.x;
half* row_ptr = data + static_cast<long long>(row) * HDIM;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float val = __half2float(v.h[j]);
sq += val * val;
}
}
float inv = rsqrtf(block_reduce_sum(sq) / HDIM + RMS_EPS);
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v, sc;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
sc.f2 = *reinterpret_cast<const float2*>(scale + i);
#pragma unroll
for (int j = 0; j < 4; j++)
v.h[j] = __float2half_rn(__half2float(v.h[j]) * inv * __half2float(sc.h[j]));
*reinterpret_cast<float2*>(row_ptr + i) = v.f2;
}
}
__global__ __launch_bounds__(256, 4)
void rope_kernel(half* __restrict__ q,
half* __restrict__ k,
const half* __restrict__ pe,
int batch,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = batch * HEADS * seq * (HDIM / 2);
if (idx >= total) {
return;
}
int pair = idx % (HDIM / 2);
int t0 = idx / (HDIM / 2);
int s = t0 % seq;
int t1 = t0 / seq;
int h = t1 % HEADS;
int b = t1 / HEADS;
long long base = (((static_cast<long long>(b) * HEADS + h) * seq) + s) * HDIM + 2 * pair;
long long pe_off = (static_cast<long long>(s) * (HDIM / 2) + pair) * 2;
VecHalf2 pe_v;
pe_v.u = *reinterpret_cast<const unsigned int*>(pe + pe_off);
float c = __half2float(pe_v.h[0]);
float sn = __half2float(pe_v.h[1]);
VecHalf2 qv;
qv.u = *reinterpret_cast<const unsigned int*>(q + base);
float q0 = __half2float(qv.h[0]);
float q1 = __half2float(qv.h[1]);
qv.h[0] = __float2half_rn(q0 * c - q1 * sn);
qv.h[1] = __float2half_rn(q0 * sn + q1 * c);
*reinterpret_cast<unsigned int*>(q + base) = qv.u;
VecHalf2 kv;
kv.u = *reinterpret_cast<const unsigned int*>(k + base);
float k0 = __half2float(kv.h[0]);
float k1 = __half2float(kv.h[1]);
kv.h[0] = __float2half_rn(k0 * c - k1 * sn);
kv.h[1] = __float2half_rn(k0 * sn + k1 * c);
*reinterpret_cast<unsigned int*>(k + base) = kv.u;
}
__global__ __launch_bounds__(256, 4)
void gelu_tanh_kernel(half* __restrict__ data,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(data + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
float x3 = x * x * x;
v.h[j] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
*reinterpret_cast<float4*>(data + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(data[i]);
float x3 = x * x * x;
data[i] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
}
}
__global__ __launch_bounds__(256, 6)
void concat_final_kernel(const half* __restrict__ attn,
const half* __restrict__ mlp,
half* __restrict__ out,
int rows)
{
int total = rows * LIN2DIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / LIN2DIM;
int col = base % LIN2DIM;
if (col + 7 < LIN2DIM) {
float4 v;
if (col + 7 < HIDDEN) {
v = *reinterpret_cast<const float4*>(attn + static_cast<long long>(row) * HIDDEN + col);
} else if (col >= HIDDEN) {
v = *reinterpret_cast<const float4*>(mlp + static_cast<long long>(row) * FFDIM + (col - HIDDEN));
} else {
VecHalf8 vh;
#pragma unroll
for (int j = 0; j < 8; j++) {
int c = col + j;
if (c < HIDDEN)
vh.h[j] = attn[static_cast<long long>(row) * HIDDEN + c];
else
vh.h[j] = mlp[static_cast<long long>(row) * FFDIM + (c - HIDDEN)];
}
v = vh.f4;
}
*reinterpret_cast<float4*>(out + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / LIN2DIM;
int col = idx % LIN2DIM;
if (col < HIDDEN)
out[idx] = attn[static_cast<long long>(row) * HIDDEN + col];
else
out[idx] = mlp[static_cast<long long>(row) * FFDIM + (col - HIDDEN)];
}
}
__global__ void gate_residual_kernel(const half* __restrict__ residual,
const half* __restrict__ gate,
half* __restrict__ out,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = gridDim.y * seq * HIDDEN;
int linear = blockIdx.y * (seq * HIDDEN) + idx;
if (linear >= total) {
return;
}
int h = linear % HIDDEN;
int token = linear / HIDDEN;
int b = token / seq;
float gate_v = __half2float(gate[static_cast<long long>(b) * HIDDEN + h]);
float res = __half2float(residual[linear]);
float v = __half2float(out[linear]);
out[linear] = __float2half_rn(res + gate_v * v);
}
// =========================================================================
// SSBEngine — FP16-only (no FP8, no CUTLASS)
// =========================================================================
SSBEngine::SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size)
: B_(batch),
S_(seq),
cub_(nullptr),
workspace_(nullptr),
workspace_bytes_(0),
d_silu_(nullptr),
d_mod_(nullptr),
d_xmod_(nullptr),
d_l1o_(nullptr)
{
BK(cublasCreate(&cub_));
BK(cublasSetMathMode(cub_, CUBLAS_TENSOR_OP_MATH));
size_t min_needed = ssb_workspace_bytes(B_, S_);
if (workspace_buf_size < min_needed) {
throw std::runtime_error("Workspace buffer too small: need " +
std::to_string(min_needed) + " got " + std::to_string(workspace_buf_size));
}
char* p = static_cast<char*>(workspace_buf);
size_t off = 0;
size_t rows = static_cast<size_t>(B_) * S_;
#define CARVE(ptr, type, count) \
off = (off + 255) & ~size_t(255); \
ptr = reinterpret_cast<type*>(p + off); \
off += static_cast<size_t>(count) * sizeof(type);
CARVE(d_silu_, half, B_ * HIDDEN)
CARVE(d_mod_, half, static_cast<size_t>(B_) * MODDIM)
CARVE(d_xmod_, half, rows * HIDDEN)
CARVE(d_l1o_, half, rows * LIN1DIM)
#undef CARVE
off = (off + 255) & ~size_t(255);
workspace_ = p + off;
workspace_bytes_ = workspace_buf_size - off;
}
SSBEngine::~SSBEngine()
{
if (cub_) cublasDestroy(cub_);
}
void SSBEngine::prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// SiLU on vec
silu_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_vec, d_silu_, B_ * HIDDEN);
// Modulation GEMM: FP16→FP16
linear_gemm(cub_, B_, MODDIM, HIDDEN, d_silu_, mod_w, d_mod_);
int out_n = B_ * MODDIM;
bias_add_kernel<<<(out_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_mod_, mod_b, B_, MODDIM);
// LayerNorm + Modulation (reads x as BF16, outputs FP16)
layernorm_mod_kernel<<<rows, threads, 0, stream>>>(reinterpret_cast<const __nv_bfloat16*>(d_x), d_mod_, d_xmod_, S_);
// Linear1 GEMM: FP16→FP16
linear_gemm(cub_, rows, LIN1DIM, HIDDEN, d_xmod_, l1w, d_l1o_);
int l1_n = rows * LIN1DIM;
bias_add_kernel<<<(l1_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_l1o_, l1b, rows, LIN1DIM);
// Split Q/K/V from Linear1 output
dim3 split_grid((S_ * HIDDEN + threads - 1) / threads, B_);
split_qkv_kernel<<<split_grid, threads, 0, stream>>>(d_l1o_, d_q, d_k, d_v, S_);
// Copy MLP portion
copy_mlp_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_l1o_, d_mlp, rows);
// Extract gate from modulation output
extract_gate_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mod_, d_gate, B_);
// RMSNorm + scale on Q and K
int qk_rows = B_ * HEADS * S_;
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_q, qns);
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_k, kns);
// RoPE
int rope_total = B_ * HEADS * S_ * (HDIM / 2);
rope_kernel<<<(rope_total + threads - 1) / threads, threads, 0, stream>>>(d_q, d_k, d_pe, B_, S_);
CK(cudaGetLastError());
}
void SSBEngine::finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// GELU on MLP
gelu_tanh_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mlp, rows * FFDIM);
// Concat attention + MLP → d_l1o_ (reused as temp)
concat_final_kernel<<<(rows * LIN2DIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_attn, d_mlp, d_l1o_, rows);
// Linear2 GEMM: FP16→FP16
linear_gemm(cub_, rows, HIDDEN, LIN2DIM, d_l1o_, l2w, d_out);
// Bias add
int out_blocks = (rows * HIDDEN + threads * 4 - 1) / (threads * 4);
bias_add_kernel<<<out_blocks, threads, 0, stream>>>(d_out, l2b, rows, HIDDEN);
// Gate + residual: out = x + gate * out
dim3 gate_grid((S_ * HIDDEN + threads - 1) / threads, B_);
gate_residual_kernel<<<gate_grid, threads, 0, stream>>>(d_x, d_gate, d_out, S_);
CK(cudaGetLastError());
}
} // namespace transformer
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"""
Build script for flux_ext FP16 PyTorch C++/CUDA extension — 20-series (SM 75, Turing).
Usage:
py -3.10 setup_ext.py install
Compiles the FP16-only FLUXNATION kernel (no FP8, no CUTLASS).
Compatible with RTX 2060, 2070, 2080, 2080 Ti.
"""
import os
os.environ["CUDA_HOME"] = r"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.8"
os.environ["CUDA_PATH"] = os.environ["CUDA_HOME"]
from setuptools import setup
from torch.utils.cpp_extension import CUDAExtension, BuildExtension
ROOT = os.path.dirname(os.path.abspath(__file__))
setup(
name="flux_ext",
ext_modules=[
CUDAExtension(
name="flux_ext",
sources=[
os.path.join(ROOT, "csrc", "FLUXPATCH_FP16.cpp"),
os.path.join(ROOT, "csrc", "FLUXNATION_FP16.cu"),
os.path.join(ROOT, "flux_opt_fp16.cu"),
],
include_dirs=[
ROOT, # SINGLE_STREAM_BLOCK_FP16.H
],
extra_compile_args={
"cxx": ["/O2", "/std:c++17", "/EHsc", "/MD"],
"nvcc": [
"-O3",
"-std=c++17",
"-arch=sm_75",
"-DFLUX_TORCH_EXT=1",
"--allow-unsupported-compiler",
"-diag-suppress=20013",
"-diag-suppress=20015",
"-Xcompiler", "/MD",
"-Xcompiler", "/EHsc",
"-Xcompiler", "/Zc:preprocessor",
],
},
libraries=["cublas"],
)
],
cmdclass={"build_ext": BuildExtension},
)
@@ -0,0 +1,106 @@
#ifndef SINGLE_STREAM_BLOCK_FP16_H
#define SINGLE_STREAM_BLOCK_FP16_H
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <cublas_v2.h>
#include <cstdio>
#include <stdexcept>
#include <string>
namespace transformer {
constexpr int HIDDEN = 3072;
constexpr int HEADS = 24;
constexpr int HDIM = 128;
constexpr int FFDIM = 12288;
constexpr int MODDIM = 3 * HIDDEN;
constexpr int LIN1DIM = 3 * HIDDEN + FFDIM;
constexpr int LIN2DIM = HIDDEN + FFDIM;
constexpr float LN_EPS = 1e-6f;
constexpr float RMS_EPS = 1e-6f;
constexpr float ATT_SC = 0.0883883476f;
static int const kKernelThreads = 256;
static_assert((kKernelThreads % 32) == 0, "kKernelThreads must be a multiple of 32.");
#define CK(call) do { \
cudaError_t err__ = (call); \
if (err__ != cudaSuccess) { \
throw std::runtime_error(std::string("CUDA ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + cudaGetErrorString(err__)); \
} \
} while (0)
#define BK(call) do { \
cublasStatus_t st__ = (call); \
if (st__ != CUBLAS_STATUS_SUCCESS) { \
throw std::runtime_error(std::string("cuBLAS ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + std::to_string((int)st__)); \
} \
} while (0)
static inline size_t ssb_workspace_bytes(int batch, int seq) {
size_t rows = static_cast<size_t>(batch) * seq;
size_t b = static_cast<size_t>(batch);
size_t sz = 0;
#define ADDBUF(count, elem_size) \
sz = (sz + 255) & ~size_t(255); sz += (count) * (elem_size);
ADDBUF(b * HIDDEN, 2); // d_silu_
ADDBUF(b * MODDIM, 2); // d_mod_
ADDBUF(rows * HIDDEN, 2); // d_xmod_
ADDBUF(rows * LIN1DIM, 2); // d_l1o_
sz = (sz + 255) & ~size_t(255);
sz += 32ull << 20; // 32MB cuBLAS workspace
#undef ADDBUF
return sz;
}
class SSBEngine {
public:
SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size);
~SSBEngine();
void prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream = 0);
void finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream = 0);
int batch() const { return B_; }
int seq() const { return S_; }
private:
int B_;
int S_;
cublasHandle_t cub_;
void* workspace_;
size_t workspace_bytes_;
half* d_silu_;
half* d_mod_;
half* d_xmod_;
half* d_l1o_;
};
} // namespace transformer
#endif // SINGLE_STREAM_BLOCK_FP16_H
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@echo off
setlocal
REM FLUXNATION FP16 Build — 30-series (SM 86, Ampere)
REM Compatible with RTX 3060/3070/3080/3090
set "VSVARS=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
if not exist "%VSVARS%" (
echo [flux_ext] ERROR: VS 2022 vcvars64.bat not found
exit /b 1
)
call "%VSVARS%" || exit /b 1
set DISTUTILS_USE_SDK=1
echo [flux_ext] Building FLUXNATION FP16 for 30-series (SM 86)...
py -3.10 setup_ext.py install
if errorlevel 1 (
echo [flux_ext] Build FAILED
exit /b 1
)
echo [flux_ext] Build succeeded! flux_ext (FP16, SM 86) is now installed.
echo [flux_ext] Restart ComfyUI to use the new kernel.
+198
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/*
* FLUXNATION_FP16.cu — PyTorch C++ extension for FLUXNATION (FP16-only)
*
* Wraps the FP16 SSBEngine as torch.ops custom operators.
* All weights converted to FP16 internally — no FP8, no CUTLASS.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include <torch/extension.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <unordered_map>
#include <memory>
#include <mutex>
using namespace transformer;
// =========================================================================
// Global engine cache — keyed by (device, batch, seq_len)
// =========================================================================
struct EngineEntry {
std::unique_ptr<SSBEngine> engine;
at::Tensor workspace;
};
static std::unordered_map<int64_t, EngineEntry> g_engine_cache;
static std::mutex g_engine_mutex;
static int64_t make_engine_key(int device, int batch, int seq) {
return (int64_t)device * 1000000000LL + (int64_t)batch * 1000000LL + seq;
}
static SSBEngine* get_or_create_engine(int batch, int seq, at::Device device) {
int dev_idx = device.index();
int64_t key = make_engine_key(dev_idx, batch, seq);
std::lock_guard<std::mutex> lock(g_engine_mutex);
auto it = g_engine_cache.find(key);
if (it != g_engine_cache.end()) {
return it->second.engine.get();
}
at::cuda::CUDAGuard guard(device);
size_t ws_bytes = ssb_workspace_bytes(batch, seq);
auto ws_tensor = at::empty({(int64_t)ws_bytes}, at::TensorOptions().dtype(at::kByte).device(device));
auto engine = std::make_unique<SSBEngine>(batch, seq, ws_tensor.data_ptr(), ws_bytes);
auto* ptr = engine.get();
EngineEntry entry;
entry.engine = std::move(engine);
entry.workspace = ws_tensor;
g_engine_cache[key] = std::move(entry);
fprintf(stderr, "[flux_ext FP16] Created engine B=%d S=%d ws=%.1fMB dev=%d\n",
batch, seq, ws_bytes / (1024.0 * 1024.0), dev_idx);
fflush(stderr);
return ptr;
}
// =========================================================================
// torch.ops implementation: ssb_prepare
//
// Same Python API as FP8 version — scale tensors are accepted but ignored.
// All weights converted to FP16 internally.
// =========================================================================
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, // [B, S, 3072] bf16
at::Tensor vec, // [B, 3072] or [B, 1, 3072] fp16
at::Tensor pe, // [S, 64, 2] fp16
at::Tensor mod_w, // weight (any dtype → converted to FP16)
at::Tensor mod_w_scale, // IGNORED in FP16 mode
at::Tensor mod_b, // fp16
at::Tensor l1w, // weight (any dtype → converted to FP16)
at::Tensor l1w_scale, // IGNORED in FP16 mode
at::Tensor l1b, // fp16
at::Tensor qns, // fp16
at::Tensor kns) // fp16
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Ensure correct dtypes — x stays BF16 (layernorm kernel reads it as BF16)
auto x_bf16 = x.to(at::kBFloat16).contiguous();
auto vec_fp16 = vec.dim() == 3 ? vec.squeeze(1).to(at::kHalf).contiguous()
: vec.to(at::kHalf).contiguous();
auto pe_fp16 = pe.to(at::kHalf).contiguous();
// Convert ALL weights to FP16 (no FP8 on this target)
auto mod_w_fp16 = mod_w.to(at::kHalf).contiguous();
auto mod_b_fp16 = mod_b.to(at::kHalf).contiguous();
auto l1w_fp16 = l1w.to(at::kHalf).contiguous();
auto l1b_fp16 = l1b.to(at::kHalf).contiguous();
auto qns_fp16 = qns.to(at::kHalf).contiguous();
auto kns_fp16 = kns.to(at::kHalf).contiguous();
// Allocate output tensors
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto q = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto k = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto v = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto mlp = at::empty({B, S, FFDIM}, opts_fp16);
auto gate = at::empty({B, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->prepare(
reinterpret_cast<const half*>(x_bf16.data_ptr()),
reinterpret_cast<const half*>(vec_fp16.data_ptr()),
reinterpret_cast<const half*>(pe_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_w_fp16.data_ptr()),
reinterpret_cast<const half*>(mod_b_fp16.data_ptr()),
reinterpret_cast<const half*>(l1w_fp16.data_ptr()),
reinterpret_cast<const half*>(l1b_fp16.data_ptr()),
reinterpret_cast<const half*>(qns_fp16.data_ptr()),
reinterpret_cast<const half*>(kns_fp16.data_ptr()),
reinterpret_cast<half*>(q.data_ptr()),
reinterpret_cast<half*>(k.data_ptr()),
reinterpret_cast<half*>(v.data_ptr()),
reinterpret_cast<half*>(mlp.data_ptr()),
reinterpret_cast<half*>(gate.data_ptr()),
stream);
return std::make_tuple(q, k, v, mlp, gate);
}
// =========================================================================
// torch.ops implementation: ssb_finish
//
// FP16 path: converts residual (x) from BF16→FP16, runs all-FP16 engine,
// converts result back to BF16 for model compatibility.
// =========================================================================
at::Tensor ssb_finish_impl(
at::Tensor x, // [B, S, 3072] bf16 — original input for residual
at::Tensor attn, // [B, S, 3072] fp16 — attention output
at::Tensor mlp, // [B, S, 12288] fp16 — MLP intermediate (pre-GELU)
at::Tensor gate, // [B, 3072] fp16 — gate values
at::Tensor l2w, // weight (any dtype → converted to FP16)
at::Tensor l2w_scale, // IGNORED in FP16 mode
at::Tensor l2b) // fp16 — L2 bias
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Convert residual from BF16 to FP16 for the FP16 engine
auto x_fp16 = x.to(at::kHalf).contiguous();
auto attn_fp16 = attn.to(at::kHalf).contiguous();
auto mlp_c = mlp.contiguous();
auto gate_c = gate.contiguous();
auto l2w_fp16 = l2w.to(at::kHalf).contiguous();
auto l2b_fp16 = l2b.to(at::kHalf).contiguous();
// Result in FP16 (engine is all-FP16)
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto result_fp16 = at::empty({B, S, HIDDEN}, opts_fp16);
SSBEngine* engine = get_or_create_engine(B, S, device);
engine->finish(
reinterpret_cast<const half*>(x_fp16.data_ptr()),
reinterpret_cast<const half*>(attn_fp16.data_ptr()),
reinterpret_cast<half*>(mlp_c.data_ptr()),
reinterpret_cast<const half*>(gate_c.data_ptr()),
reinterpret_cast<half*>(result_fp16.data_ptr()),
reinterpret_cast<const half*>(l2w_fp16.data_ptr()),
reinterpret_cast<const half*>(l2b_fp16.data_ptr()),
stream);
// Convert back to BF16 for model compatibility
return result_fp16.to(at::kBFloat16);
}
// =========================================================================
// Cleanup — destroys all cached engines
// =========================================================================
void ssb_cleanup_impl() {
std::lock_guard<std::mutex> lock(g_engine_mutex);
g_engine_cache.clear();
fprintf(stderr, "[flux_ext FP16] All engines destroyed\n");
fflush(stderr);
}
@@ -0,0 +1,49 @@
/*
* FLUXPATCH_FP16.cpp — TORCH_LIBRARY registration for FLUXNATION (FP16-only)
*
* Registers ssb_prepare and ssb_finish as torch.ops.flux_ext.* custom ops.
* Identical API to the FP8 version — Python code doesn't change.
*/
#include <torch/extension.h>
#include <ATen/ATen.h>
// Forward declarations (in FLUXNATION_FP16.cu)
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, at::Tensor vec, at::Tensor pe,
at::Tensor mod_w, at::Tensor mod_w_scale, at::Tensor mod_b,
at::Tensor l1w, at::Tensor l1w_scale, at::Tensor l1b,
at::Tensor qns, at::Tensor kns);
at::Tensor ssb_finish_impl(
at::Tensor x, at::Tensor attn, at::Tensor mlp, at::Tensor gate,
at::Tensor l2w, at::Tensor l2w_scale, at::Tensor l2b);
void ssb_cleanup_impl();
TORCH_LIBRARY(flux_ext, m) {
m.def("ssb_prepare("
"Tensor x, Tensor vec, Tensor pe, "
"Tensor mod_w, Tensor mod_w_scale, Tensor mod_b, "
"Tensor l1w, Tensor l1w_scale, Tensor l1b, "
"Tensor qns, Tensor kns"
") -> (Tensor, Tensor, Tensor, Tensor, Tensor)");
m.def("ssb_finish("
"Tensor x, Tensor attn, Tensor mlp, Tensor gate, "
"Tensor l2w, Tensor l2w_scale, Tensor l2b"
") -> Tensor");
m.def("ssb_cleanup() -> ()");
}
TORCH_LIBRARY_IMPL(flux_ext, CUDA, m) {
m.impl("ssb_prepare", &ssb_prepare_impl);
m.impl("ssb_finish", &ssb_finish_impl);
m.impl("ssb_cleanup", &ssb_cleanup_impl);
}
PYBIND11_MODULE(flux_ext, m) {
m.doc() = "FLUXNATION FP16: Fused CUDA kernels for FLUX.1 SingleStreamBlock (no FP8)";
}
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/*
* flux_opt_fp16.cu — FP16-only SSBEngine for FLUXNATION
*
* Derived from flux_opt.cu. All FP8/CUTLASS code removed.
* Uses cuBLAS FP16 tensor-op GEMMs only.
* Compatible with SM 61+ (Pascal, Turing, Ampere).
*/
#include "SINGLE_STREAM_BLOCK_FP16.H"
#include <algorithm>
#include <cfloat>
#include <cmath>
#include <cstdlib>
namespace transformer {
// Vectorized load/store helpers — 128-bit (8 half elements) for max bandwidth
union VecHalf8 {
float4 f4;
half h[8];
};
union VecHalf4 {
float2 f2;
half h[4];
};
union VecHalf2 {
unsigned int u;
half h[2];
};
union VecBF16_4 {
float2 f2;
__nv_bfloat16 b[4];
};
union VecBF16_8 {
float4 f4;
__nv_bfloat16 b[8];
};
// FP16 GEMM via cuBLAS with tensor-op math
static inline void linear_gemm(cublasHandle_t cub,
int m,
int n,
int k,
const half* x,
const half* w_torch,
half* y)
{
const float alpha = 1.0f;
const float beta = 0.0f;
BK(cublasGemmEx(
cub,
CUBLAS_OP_T,
CUBLAS_OP_N,
n, m, k,
&alpha,
w_torch, CUDA_R_16F, k,
x, CUDA_R_16F, k,
&beta,
y, CUDA_R_16F, n,
CUBLAS_COMPUTE_32F_FAST_16F,
CUBLAS_GEMM_DEFAULT_TENSOR_OP));
}
__forceinline__ __device__ float warp_reduce_sum(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v += __shfl_down_sync(0xffffffff, v, offset);
}
return v;
}
__forceinline__ __device__ float warp_reduce_max(float v)
{
for (int offset = 16; offset > 0; offset >>= 1) {
v = fmaxf(v, __shfl_down_sync(0xffffffff, v, offset));
}
return v;
}
__forceinline__ __device__ float block_reduce_sum(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_sum(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : 0.0f;
x = warp_reduce_sum(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__forceinline__ __device__ float block_reduce_max(float v)
{
constexpr int kWarps = kKernelThreads / 32;
__shared__ float warp_vals[kWarps];
int lane = threadIdx.x & 31;
int wid = threadIdx.x >> 5;
v = warp_reduce_max(v);
if (lane == 0) {
warp_vals[wid] = v;
}
__syncthreads();
if (wid == 0) {
float x = (lane < kWarps) ? warp_vals[lane] : -FLT_MAX;
x = warp_reduce_max(x);
if (lane == 0) {
warp_vals[0] = x;
}
}
__syncthreads();
return warp_vals[0];
}
__global__ __launch_bounds__(256, 4)
void silu_kernel(const half* __restrict__ in,
half* __restrict__ out,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(in + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
v.h[j] = __float2half_rn(x / (1.0f + expf(-x)));
}
*reinterpret_cast<float4*>(out + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(in[i]);
out[i] = __float2half_rn(x / (1.0f + expf(-x)));
}
}
}
__global__ __launch_bounds__(256, 4)
void bias_add_kernel(half* __restrict__ out,
const half* __restrict__ bias,
int rows,
int cols)
{
int total = rows * cols;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 4;
if (base + 3 < total) {
int col = base % cols;
if (col + 3 < cols) {
VecHalf4 ov, bv;
ov.f2 = *reinterpret_cast<const float2*>(out + base);
bv.f2 = *reinterpret_cast<const float2*>(bias + col);
#pragma unroll
for (int j = 0; j < 4; j++)
ov.h[j] = __float2half_rn(__half2float(ov.h[j]) + __half2float(bv.h[j]));
*reinterpret_cast<float2*>(out + base) = ov.f2;
return;
}
}
for (int j = 0; j < 4 && base + j < total; j++) {
int idx = base + j;
int col = idx % cols;
float v = __half2float(out[idx]) + __half2float(bias[col]);
out[idx] = __float2half_rn(v);
}
}
// Input x is bf16 (model runs in bf16). Output is fp16. BF16→FP16 conversion is
// software-emulated on SM < 80 but is IO-bound so negligible overhead.
__global__ __launch_bounds__(256, 2)
void layernorm_mod_kernel(const __nv_bfloat16* __restrict__ x,
const half* __restrict__ mod,
half* __restrict__ out,
int seq)
{
int row = blockIdx.x;
int b = row / seq;
const __nv_bfloat16* x_row = x + static_cast<long long>(row) * HIDDEN;
half* out_row = out + static_cast<long long>(row) * HIDDEN;
const half* shift = mod + static_cast<long long>(b) * MODDIM;
const half* scale = shift + HIDDEN;
float sum = 0.0f;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 bv;
bv.f2 = *reinterpret_cast<const float2*>(x_row + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(bv.b[j]);
sum += v;
sq += v * v;
}
}
float mean = block_reduce_sum(sum) / HIDDEN;
float var = block_reduce_sum(sq) / HIDDEN - mean * mean;
float inv = rsqrtf(var + LN_EPS);
for (int i = threadIdx.x * 4; i < HIDDEN; i += blockDim.x * 4) {
VecBF16_4 xv;
xv.f2 = *reinterpret_cast<const float2*>(x_row + i);
VecHalf4 sc_v, sh_v, ov;
sc_v.f2 = *reinterpret_cast<const float2*>(scale + i);
sh_v.f2 = *reinterpret_cast<const float2*>(shift + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float v = __bfloat162float(xv.b[j]);
float nrm = (v - mean) * inv;
ov.h[j] = __float2half_rn(nrm * (1.0f + __half2float(sc_v.h[j])) + __half2float(sh_v.h[j]));
}
*reinterpret_cast<float2*>(out_row + i) = ov.f2;
}
}
__global__ void split_qkv_kernel(const half* __restrict__ l1o,
half* __restrict__ q,
half* __restrict__ k,
half* __restrict__ v,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = seq * HIDDEN;
int batch_total = gridDim.y;
int linear = blockIdx.y * total + idx;
int max_linear = batch_total * total;
if (linear >= max_linear) return;
int token = linear / HIDDEN;
int h = linear % HIDDEN;
int b = token / seq;
int s = token % seq;
int head = h / HDIM;
int d = h % HDIM;
long long base_l1 = static_cast<long long>(token) * LIN1DIM;
long long dst = (((static_cast<long long>(b) * HEADS + head) * seq) + s) * HDIM + d;
q[dst] = l1o[base_l1 + h];
k[dst] = l1o[base_l1 + HIDDEN + h];
v[dst] = l1o[base_l1 + 2 * HIDDEN + h];
}
__global__ __launch_bounds__(256, 6)
void copy_mlp_kernel(const half* __restrict__ l1o,
half* __restrict__ mlp,
int rows)
{
int total = rows * FFDIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / FFDIM;
int col = base % FFDIM;
if (col + 7 < FFDIM) {
float4 v = *reinterpret_cast<const float4*>(l1o + static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col);
*reinterpret_cast<float4*>(mlp + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / FFDIM;
int col = idx % FFDIM;
mlp[idx] = l1o[static_cast<long long>(row) * LIN1DIM + 3 * HIDDEN + col];
}
}
__global__ __launch_bounds__(256, 6)
void extract_gate_kernel(const half* __restrict__ mod,
half* __restrict__ gate,
int batch)
{
int total = batch * HIDDEN;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int b = base / HIDDEN;
int h = base % HIDDEN;
if (h + 7 < HIDDEN) {
float4 v = *reinterpret_cast<const float4*>(mod + static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h);
*reinterpret_cast<float4*>(gate + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int b = idx / HIDDEN;
int h = idx % HIDDEN;
gate[idx] = mod[static_cast<long long>(b) * MODDIM + 2 * HIDDEN + h];
}
}
__global__ __launch_bounds__(256, 2)
void rmsnorm_scale_kernel(half* __restrict__ data,
const half* __restrict__ scale)
{
int row = blockIdx.x;
half* row_ptr = data + static_cast<long long>(row) * HDIM;
float sq = 0.0f;
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
#pragma unroll
for (int j = 0; j < 4; j++) {
float val = __half2float(v.h[j]);
sq += val * val;
}
}
float inv = rsqrtf(block_reduce_sum(sq) / HDIM + RMS_EPS);
for (int i = threadIdx.x * 4; i < HDIM; i += blockDim.x * 4) {
VecHalf4 v, sc;
v.f2 = *reinterpret_cast<const float2*>(row_ptr + i);
sc.f2 = *reinterpret_cast<const float2*>(scale + i);
#pragma unroll
for (int j = 0; j < 4; j++)
v.h[j] = __float2half_rn(__half2float(v.h[j]) * inv * __half2float(sc.h[j]));
*reinterpret_cast<float2*>(row_ptr + i) = v.f2;
}
}
__global__ __launch_bounds__(256, 4)
void rope_kernel(half* __restrict__ q,
half* __restrict__ k,
const half* __restrict__ pe,
int batch,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = batch * HEADS * seq * (HDIM / 2);
if (idx >= total) {
return;
}
int pair = idx % (HDIM / 2);
int t0 = idx / (HDIM / 2);
int s = t0 % seq;
int t1 = t0 / seq;
int h = t1 % HEADS;
int b = t1 / HEADS;
long long base = (((static_cast<long long>(b) * HEADS + h) * seq) + s) * HDIM + 2 * pair;
long long pe_off = (static_cast<long long>(s) * (HDIM / 2) + pair) * 2;
VecHalf2 pe_v;
pe_v.u = *reinterpret_cast<const unsigned int*>(pe + pe_off);
float c = __half2float(pe_v.h[0]);
float sn = __half2float(pe_v.h[1]);
VecHalf2 qv;
qv.u = *reinterpret_cast<const unsigned int*>(q + base);
float q0 = __half2float(qv.h[0]);
float q1 = __half2float(qv.h[1]);
qv.h[0] = __float2half_rn(q0 * c - q1 * sn);
qv.h[1] = __float2half_rn(q0 * sn + q1 * c);
*reinterpret_cast<unsigned int*>(q + base) = qv.u;
VecHalf2 kv;
kv.u = *reinterpret_cast<const unsigned int*>(k + base);
float k0 = __half2float(kv.h[0]);
float k1 = __half2float(kv.h[1]);
kv.h[0] = __float2half_rn(k0 * c - k1 * sn);
kv.h[1] = __float2half_rn(k0 * sn + k1 * c);
*reinterpret_cast<unsigned int*>(k + base) = kv.u;
}
__global__ __launch_bounds__(256, 4)
void gelu_tanh_kernel(half* __restrict__ data,
int n)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < n) {
VecHalf8 v;
v.f4 = *reinterpret_cast<const float4*>(data + base);
#pragma unroll
for (int j = 0; j < 8; j++) {
float x = __half2float(v.h[j]);
float x3 = x * x * x;
v.h[j] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
*reinterpret_cast<float4*>(data + base) = v.f4;
} else {
for (int i = base; i < min(base + 8, n); i++) {
float x = __half2float(data[i]);
float x3 = x * x * x;
data[i] = __float2half_rn(0.5f * x * (1.0f + tanhf(0.7978845608f * (x + 0.044715f * x3))));
}
}
}
__global__ __launch_bounds__(256, 6)
void concat_final_kernel(const half* __restrict__ attn,
const half* __restrict__ mlp,
half* __restrict__ out,
int rows)
{
int total = rows * LIN2DIM;
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base + 7 < total) {
int row = base / LIN2DIM;
int col = base % LIN2DIM;
if (col + 7 < LIN2DIM) {
float4 v;
if (col + 7 < HIDDEN) {
v = *reinterpret_cast<const float4*>(attn + static_cast<long long>(row) * HIDDEN + col);
} else if (col >= HIDDEN) {
v = *reinterpret_cast<const float4*>(mlp + static_cast<long long>(row) * FFDIM + (col - HIDDEN));
} else {
VecHalf8 vh;
#pragma unroll
for (int j = 0; j < 8; j++) {
int c = col + j;
if (c < HIDDEN)
vh.h[j] = attn[static_cast<long long>(row) * HIDDEN + c];
else
vh.h[j] = mlp[static_cast<long long>(row) * FFDIM + (c - HIDDEN)];
}
v = vh.f4;
}
*reinterpret_cast<float4*>(out + base) = v;
return;
}
}
for (int j = 0; j < 8 && base + j < total; j++) {
int idx = base + j;
int row = idx / LIN2DIM;
int col = idx % LIN2DIM;
if (col < HIDDEN)
out[idx] = attn[static_cast<long long>(row) * HIDDEN + col];
else
out[idx] = mlp[static_cast<long long>(row) * FFDIM + (col - HIDDEN)];
}
}
__global__ void gate_residual_kernel(const half* __restrict__ residual,
const half* __restrict__ gate,
half* __restrict__ out,
int seq)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
int total = gridDim.y * seq * HIDDEN;
int linear = blockIdx.y * (seq * HIDDEN) + idx;
if (linear >= total) {
return;
}
int h = linear % HIDDEN;
int token = linear / HIDDEN;
int b = token / seq;
float gate_v = __half2float(gate[static_cast<long long>(b) * HIDDEN + h]);
float res = __half2float(residual[linear]);
float v = __half2float(out[linear]);
out[linear] = __float2half_rn(res + gate_v * v);
}
// =========================================================================
// SSBEngine — FP16-only (no FP8, no CUTLASS)
// =========================================================================
SSBEngine::SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size)
: B_(batch),
S_(seq),
cub_(nullptr),
workspace_(nullptr),
workspace_bytes_(0),
d_silu_(nullptr),
d_mod_(nullptr),
d_xmod_(nullptr),
d_l1o_(nullptr)
{
BK(cublasCreate(&cub_));
BK(cublasSetMathMode(cub_, CUBLAS_TENSOR_OP_MATH));
size_t min_needed = ssb_workspace_bytes(B_, S_);
if (workspace_buf_size < min_needed) {
throw std::runtime_error("Workspace buffer too small: need " +
std::to_string(min_needed) + " got " + std::to_string(workspace_buf_size));
}
char* p = static_cast<char*>(workspace_buf);
size_t off = 0;
size_t rows = static_cast<size_t>(B_) * S_;
#define CARVE(ptr, type, count) \
off = (off + 255) & ~size_t(255); \
ptr = reinterpret_cast<type*>(p + off); \
off += static_cast<size_t>(count) * sizeof(type);
CARVE(d_silu_, half, B_ * HIDDEN)
CARVE(d_mod_, half, static_cast<size_t>(B_) * MODDIM)
CARVE(d_xmod_, half, rows * HIDDEN)
CARVE(d_l1o_, half, rows * LIN1DIM)
#undef CARVE
off = (off + 255) & ~size_t(255);
workspace_ = p + off;
workspace_bytes_ = workspace_buf_size - off;
}
SSBEngine::~SSBEngine()
{
if (cub_) cublasDestroy(cub_);
}
void SSBEngine::prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const half* mod_w,
const half* mod_b,
const half* l1w,
const half* l1b,
const half* qns,
const half* kns,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// SiLU on vec
silu_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_vec, d_silu_, B_ * HIDDEN);
// Modulation GEMM: FP16→FP16
linear_gemm(cub_, B_, MODDIM, HIDDEN, d_silu_, mod_w, d_mod_);
int out_n = B_ * MODDIM;
bias_add_kernel<<<(out_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_mod_, mod_b, B_, MODDIM);
// LayerNorm + Modulation (reads x as BF16, outputs FP16)
layernorm_mod_kernel<<<rows, threads, 0, stream>>>(reinterpret_cast<const __nv_bfloat16*>(d_x), d_mod_, d_xmod_, S_);
// Linear1 GEMM: FP16→FP16
linear_gemm(cub_, rows, LIN1DIM, HIDDEN, d_xmod_, l1w, d_l1o_);
int l1_n = rows * LIN1DIM;
bias_add_kernel<<<(l1_n + threads * 4 - 1) / (threads * 4), threads, 0, stream>>>(d_l1o_, l1b, rows, LIN1DIM);
// Split Q/K/V from Linear1 output
dim3 split_grid((S_ * HIDDEN + threads - 1) / threads, B_);
split_qkv_kernel<<<split_grid, threads, 0, stream>>>(d_l1o_, d_q, d_k, d_v, S_);
// Copy MLP portion
copy_mlp_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_l1o_, d_mlp, rows);
// Extract gate from modulation output
extract_gate_kernel<<<(B_ * HIDDEN + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mod_, d_gate, B_);
// RMSNorm + scale on Q and K
int qk_rows = B_ * HEADS * S_;
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_q, qns);
rmsnorm_scale_kernel<<<qk_rows, threads, 0, stream>>>(d_k, kns);
// RoPE
int rope_total = B_ * HEADS * S_ * (HDIM / 2);
rope_kernel<<<(rope_total + threads - 1) / threads, threads, 0, stream>>>(d_q, d_k, d_pe, B_, S_);
CK(cudaGetLastError());
}
void SSBEngine::finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const half* l2w,
const half* l2b,
cudaStream_t stream)
{
BK(cublasSetStream(cub_, stream));
int rows = B_ * S_;
int threads = kKernelThreads;
// GELU on MLP
gelu_tanh_kernel<<<(rows * FFDIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_mlp, rows * FFDIM);
// Concat attention + MLP → d_l1o_ (reused as temp)
concat_final_kernel<<<(rows * LIN2DIM + threads * 8 - 1) / (threads * 8), threads, 0, stream>>>(d_attn, d_mlp, d_l1o_, rows);
// Linear2 GEMM: FP16→FP16
linear_gemm(cub_, rows, HIDDEN, LIN2DIM, d_l1o_, l2w, d_out);
// Bias add
int out_blocks = (rows * HIDDEN + threads * 4 - 1) / (threads * 4);
bias_add_kernel<<<out_blocks, threads, 0, stream>>>(d_out, l2b, rows, HIDDEN);
// Gate + residual: out = x + gate * out
dim3 gate_grid((S_ * HIDDEN + threads - 1) / threads, B_);
gate_residual_kernel<<<gate_grid, threads, 0, stream>>>(d_x, d_gate, d_out, S_);
CK(cudaGetLastError());
}
} // namespace transformer
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"""
Build script for flux_ext FP16 PyTorch C++/CUDA extension — 30-series (SM 86, Ampere).
Usage:
py -3.10 setup_ext.py install
Compiles the FP16-only FLUXNATION kernel (no FP8, no CUTLASS).
Compatible with RTX 3060, 3070, 3080, 3090.
"""
import os
os.environ["CUDA_HOME"] = r"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.8"
os.environ["CUDA_PATH"] = os.environ["CUDA_HOME"]
from setuptools import setup
from torch.utils.cpp_extension import CUDAExtension, BuildExtension
ROOT = os.path.dirname(os.path.abspath(__file__))
setup(
name="flux_ext",
ext_modules=[
CUDAExtension(
name="flux_ext",
sources=[
os.path.join(ROOT, "csrc", "FLUXPATCH_FP16.cpp"),
os.path.join(ROOT, "csrc", "FLUXNATION_FP16.cu"),
os.path.join(ROOT, "flux_opt_fp16.cu"),
],
include_dirs=[
ROOT, # SINGLE_STREAM_BLOCK_FP16.H
],
extra_compile_args={
"cxx": ["/O2", "/std:c++17", "/EHsc", "/MD"],
"nvcc": [
"-O3",
"-std=c++17",
"-arch=sm_86",
"-DFLUX_TORCH_EXT=1",
"--allow-unsupported-compiler",
"-diag-suppress=20013",
"-diag-suppress=20015",
"-Xcompiler", "/MD",
"-Xcompiler", "/EHsc",
"-Xcompiler", "/Zc:preprocessor",
],
},
libraries=["cublas"],
)
],
cmdclass={"build_ext": BuildExtension},
)
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"""
Monkey-patch ComfyUI's FLUX SingleStreamBlock to use FLUXNATION via torch.ops.
Architecture: torch.ops.flux_ext.ssb_prepare + torch.ops.flux_ext.ssb_finish
- Zero ctypes overhead (direct tensor passing)
- Fused gate+residual+bias in CUDA (no Python-side float32 intermediates)
- Weight caching (extracted once per module, not every forward call)
- Compatible with torch.compile (via register_fake)
Spike Attention Integration:
- After switch_pct% of diffusion steps, routes attention through neuromorphic
spike backend (block-sparse Triton kernel) instead of dense flash attention
- Saves ~90% attention FLOPs with rollback safety
- Enable via SPIKE_CONFIG dict or environment variable FLUX_SPIKE=1
"""
import math
import os
import torch
from comfy.ldm.flux.math import attention as flux_attention
# ── Spike attention import (LAZY — loaded on first use, not at startup) ──
_SPIKE_AVAILABLE = None # None = not checked yet, True/False = result
_spike_attend = None
_spike_has_triton = None
def _lazy_load_spike():
"""Load spike attention modules on first use."""
global _SPIKE_AVAILABLE, _spike_attend, _spike_has_triton
if _SPIKE_AVAILABLE is not None:
return _SPIKE_AVAILABLE
from . import FLUXATTENHUT as _FLUXATTENHUT_mod
from . import FLUXSPIKEY as _FLUXSPIKEY_mod
_spike_attend = _FLUXATTENHUT_mod.attend
_spike_has_triton = _FLUXSPIKEY_mod.has_triton
_SPIKE_AVAILABLE = True
triton_ok = _spike_has_triton() if _spike_has_triton else False
print(f"[FLUXNATION] Spike loaded (triton={'YES' if triton_ok else 'NO'})")
return _SPIKE_AVAILABLE
_FP8_DTYPE = getattr(torch, "float8_e4m3fn", None)
_FP8_MAX = 448.0
_FP32_MAX = 3.4028235e+38
# ── Spike attention configuration ──
# Override via environment: FLUX_SPIKE=1 FLUX_SPIKE_SWITCH=0.35 FLUX_SPIKE_CAP=0.35
SPIKE_CONFIG = {
"enabled": os.environ.get("FLUX_SPIKE", "0") == "1",
"switch_pct": float(os.environ.get("FLUX_SPIKE_SWITCH", "0.35")), # activate after 35%
"tau": float(os.environ.get("FLUX_SPIKE_TAU", "0.05")), # low threshold for block scoring
"leak": 0.0, # NO accumulator across SSBs
"event_cap_pct": float(os.environ.get("FLUX_SPIKE_CAP", "0.35")), # keep 35% of blocks
"cache_steps": os.environ.get("FLUX_SPIKE_CACHE", "1") == "1", # step caching ON by default
}
class SpikeController:
"""Tracks diffusion progress and manages spike attention + step caching.
Universal: works with ANY sampler (Euler=1 eval/step, Heun=2, DPM++=varies).
Progress is based on actual forward calls, not sampler step count.
Self-calibrates from the previous generation's actual call count.
Three attention modes per model eval:
1. DENSE — full flash attention (early evals + last 2 evals)
2. SPIKE — block-sparse Triton attention (compute evals in spike zone)
3. CACHED — replay previous eval's output (alternating with spike)
Each SSB block (38 per eval) is cached independently by block index.
"""
BLOCKS_PER_STEP = 38 # SingleStreamBlock count in FLUX.1
def __init__(self, config=None):
cfg = config or SPIKE_CONFIG
self.enabled = cfg.get("enabled", False)
self.switch_pct = cfg.get("switch_pct", 0.35)
self.tau = cfg.get("tau", 0.05)
self.leak = 0.0
self.event_cap_pct = cfg.get("event_cap_pct", 0.35)
self.cache_enabled = cfg.get("cache_steps", True)
# Per-generation state
self.total_steps = 0
self.call_count = 0
self._total_calls = 0 # expected total forward calls this gen
self._prev_gen_calls = 0 # actual calls from previous gen
self._logged_activation = False
self._logged_cache = False
self._spike_loaded = False
# SSB step cache
self._attn_cache = {}
self._last_compute_step = -1
def _ensure_spike_loaded(self):
if self._spike_loaded:
return
self._spike_loaded = True
if self.enabled:
_lazy_load_spike()
# Eval multipliers for ALL ComfyUI samplers (from k_diffusion model() call count)
SAMPLER_EVALS = {
"euler": 1, "euler_cfg_pp": 1,
"euler_ancestral": 1, "euler_ancestral_cfg_pp": 1,
"heun": 2, "heunpp2": 4,
"exp_heun_2_x0": 2, "exp_heun_2_x0_sde": 2,
"dpm_2": 2, "dpm_2_ancestral": 2,
"lms": 2, "dpm_fast": 1, "dpm_adaptive": 1,
"dpmpp_2s_ancestral": 2, "dpmpp_2s_ancestral_cfg_pp": 2,
"dpmpp_sde": 2, "dpmpp_sde_gpu": 2,
"dpmpp_2m": 1, "dpmpp_2m_cfg_pp": 1,
"dpmpp_2m_sde": 1, "dpmpp_2m_sde_gpu": 1,
"dpmpp_2m_sde_heun": 1, "dpmpp_2m_sde_heun_gpu": 1,
"dpmpp_3m_sde": 1, "dpmpp_3m_sde_gpu": 1,
"ddpm": 1, "ddim": 1, "lcm": 1,
"ipndm": 1, "ipndm_v": 1, "deis": 1,
"res_multistep": 1, "res_multistep_cfg_pp": 1,
"res_multistep_ancestral": 1, "res_multistep_ancestral_cfg_pp": 1,
"gradient_estimation": 1, "gradient_estimation_cfg_pp": 1,
"er_sde": 1, "seeds_2": 2, "seeds_3": 3,
"sa_solver": 2, "sa_solver_pece": 2,
"uni_pc": 1, "uni_pc_bh2": 1,
}
def begin_generation(self, total_steps: int, sampler_name: str = ""):
# Capture actual call count from previous gen for self-calibration
if self.call_count > 0:
self._prev_gen_calls = self.call_count
self.total_steps = total_steps
# Detect eval multiplier from sampler name
evals_per_step = self.SAMPLER_EVALS.get(sampler_name, 0)
if evals_per_step > 0:
# Known sampler — use exact multiplier
self._total_calls = total_steps * self.BLOCKS_PER_STEP * evals_per_step
elif self._prev_gen_calls > 0:
# Unknown sampler — use previous gen's actual count
self._total_calls = self._prev_gen_calls
else:
# First gen, unknown sampler — assume 1 eval/step
self._total_calls = total_steps * self.BLOCKS_PER_STEP
self._sampler_name = sampler_name
self.call_count = 0
self._logged_activation = False
self._logged_cache = False
self._attn_cache.clear()
self._last_compute_step = -1
@property
def total_evals(self):
"""Total expected model evaluations this generation."""
return self._total_calls // max(1, self.BLOCKS_PER_STEP)
@property
def current_eval(self):
"""Which model evaluation we're on (0-indexed)."""
if self.BLOCKS_PER_STEP <= 0:
return 0
return self.call_count // self.BLOCKS_PER_STEP
@property
def block_in_step(self):
"""Which SSB block within the current eval (0..37)."""
return self.call_count % self.BLOCKS_PER_STEP
@property
def progress(self):
"""Generation progress 0.0→1.0 based on actual forward calls."""
if self._total_calls <= 0:
return 0.0
return self.call_count / self._total_calls
def _in_spike_zone(self):
"""Check if we're in the spike-eligible zone."""
if not self.enabled:
return False
if self.progress < self.switch_pct:
return False
# Last 2 model evaluations always dense for final quality
remaining_evals = self.total_evals - self.current_eval
if remaining_evals <= 2:
return False
return True
def get_attention_mode(self):
"""Determine attention mode for current forward call.
Returns: "dense", "spike", or "cached"
"""
if not self._in_spike_zone():
return "dense"
# Lazy-load spike on first need
self._ensure_spike_loaded()
if not self.enabled:
return "dense"
# Eval index since entering spike zone
first_spike_eval = math.ceil(self.switch_pct * self.total_evals)
evals_in_zone = self.current_eval - first_spike_eval
# Guard: if negative (boundary rounding), this IS the first eval — always compute
if evals_in_zone <= 0:
return "spike"
# Alternating: even evals in zone = compute (spike), odd = cache
if not self.cache_enabled:
return "spike"
if evals_in_zone % 2 == 0:
return "spike"
else:
return "cached"
def attend(self, q, k, v):
"""Run spike attention. q/k/v are [B, heads, S, head_dim] fp16."""
neuromorph_cfg = {
"tau": self.tau,
"leak": 0.0,
"event_cap_pct": self.event_cap_pct,
}
output, new_state = _spike_attend(
q, k, v,
backend="spike",
state=None,
neuromorph=neuromorph_cfg,
)
if not self._logged_activation:
telem = new_state.get("telemetry", {})
flops = telem.get("flops_saved_pct", 0)
kept = telem.get("kept_events_pct", 0)
evals_per_step = self.total_evals / max(1, self.total_steps)
print(f"[flux_ext] SPIKE active @ eval {self.current_eval}/{self.total_evals} "
f"({self.progress*100:.0f}%) — {flops:.1f}% FLOPs saved, "
f"{kept:.1f}% events kept"
f"{' + step caching' if self.cache_enabled else ''}"
f" ({evals_per_step:.0f} eval/step)")
self._logged_activation = True
return output
def cache_attn(self, block_idx, attn_tensor):
"""Store attention output for replay on next step."""
self._attn_cache[block_idx] = attn_tensor.detach()
self._last_compute_step = self.current_eval
def get_cached_attn(self, block_idx):
"""Retrieve cached attention output."""
cached = self._attn_cache.get(block_idx)
if cached is not None and not self._logged_cache:
print(f"[flux_ext] CACHE replay active @ eval {self.current_eval}/{self.total_evals}")
self._logged_cache = True
return cached
def tick(self):
"""Call once per SSB forward() invocation."""
self.call_count += 1
# Global controller instance
_spike_controller = SpikeController()
# (output_name, path_to_weight, path_to_linear_module)
_WEIGHT_SPECS = (
("mod_w", ("modulation", "lin", "weight"), ("modulation", "lin")),
("l1w", ("linear1", "weight"), ("linear1",)),
("l2w", ("linear2", "weight"), ("linear2",)),
)
_weight_cache = {}
_pe_cache = {}
def _get_attr_path(obj, path):
cur = obj
for part in path:
cur = getattr(cur, part)
return cur
def _normalize_scale(scale, device):
return scale.to(dtype=torch.float32, device=device).reshape(1).contiguous()
def _to_f16(tensor, device):
if tensor.dtype == torch.float16 and tensor.is_contiguous() and tensor.device == device:
return tensor
return tensor.to(dtype=torch.float16, device=device).contiguous()
def _quantize_weight_to_fp8(linear_mod, weight, device):
w = _to_f16(weight, device)
amax = torch.amax(torch.abs(w)).to(dtype=torch.float32)
amax = torch.nan_to_num(amax, nan=0.0, posinf=_FP32_MAX, neginf=0.0)
scale = torch.where(amax < 1e-12, torch.ones_like(amax), amax / _FP8_MAX).reshape(1).contiguous()
inv_scale = (1.0 / scale).to(dtype=w.dtype)
w_fp8 = torch.clamp(w * inv_scale, min=-_FP8_MAX, max=_FP8_MAX).to(dtype=_FP8_DTYPE).contiguous()
with torch.no_grad():
linear_mod.weight = torch.nn.Parameter(w_fp8, requires_grad=False)
linear_mod.scale_weight = _normalize_scale(scale, device).reshape(())
return linear_mod.weight.contiguous(), _normalize_scale(linear_mod.scale_weight, device)
def _cache_weights(module, device):
"""Extract and cache all weight tensors ONCE per module. Not per forward call."""
mod_id = id(module)
if mod_id in _weight_cache:
return _weight_cache[mod_id]
materialized = {}
for name, weight_path, linear_path in _WEIGHT_SPECS:
tensor = _get_attr_path(module, weight_path)
if not tensor.is_cuda or tensor.device != device:
tensor = tensor.to(device=device)
linear_mod = _get_attr_path(module, linear_path)
if _FP8_DTYPE is not None and tensor.dtype == _FP8_DTYPE:
materialized[name] = tensor if tensor.is_contiguous() else tensor.contiguous()
scale = getattr(linear_mod, "scale_weight", None)
if scale is not None:
materialized[f"{name}_scale"] = _normalize_scale(scale, device)
else:
materialized[f"{name}_scale"] = torch.ones(1, dtype=torch.float32, device=device)
else:
materialized[name], materialized[f"{name}_scale"] = _quantize_weight_to_fp8(
linear_mod, tensor, device
)
for name, attr_path in (
("mod_b", ("modulation", "lin", "bias")),
("l1b", ("linear1", "bias")),
("l2b", ("linear2", "bias")),
("qns", ("norm", "query_norm", "weight")),
("kns", ("norm", "key_norm", "weight")),
):
tensor = _get_attr_path(module, attr_path)
if tensor is None:
materialized[name] = torch.zeros(1, dtype=torch.float16, device=device)
continue
if not tensor.is_cuda or tensor.device != device:
tensor = tensor.to(device=device)
materialized[name] = _to_f16(tensor, device)
_weight_cache[mod_id] = materialized
return materialized
def _convert_pe(pe):
"""Convert PE tensor from [1,1,S,64,2,1] to [S,64,2] fp16."""
pe_key = (pe.data_ptr(), pe.shape)
if pe_key in _pe_cache:
return _pe_cache[pe_key]
pe_cos = pe[0, 0, :, :, 0, 0]
pe_sin = pe[0, 0, :, :, 1, 0]
result = torch.stack([pe_cos, pe_sin], dim=-1).to(dtype=torch.float16, device=pe.device).contiguous()
_pe_cache[pe_key] = result
return result
def patched_forward(self, x, vec, pe, attn_mask=None, modulation_dims=None, transformer_options={}):
b, s, h = x.shape
if not (x.is_cuda and h == 3072 and self.num_heads == 24
and modulation_dims is None and pe is not None):
raise RuntimeError(
f"[flux_ext] Unsupported block: cuda={x.is_cuda} h={h} heads={self.num_heads}"
)
device = x.device
weights = _cache_weights(self, device)
# Convert inputs (no-op if already correct dtype/contiguity)
pe_h = _convert_pe(pe)
# ── PREPARE: one torch.ops call replaces 19 ctypes args ──
q, k, v, mlp, gate = torch.ops.flux_ext.ssb_prepare(
x, vec, pe_h,
weights["mod_w"], weights["mod_w_scale"], weights["mod_b"],
weights["l1w"], weights["l1w_scale"], weights["l1b"],
weights["qns"], weights["kns"],
)
# ── ATTENTION: dense / spike / cached ──
attn_mode = _spike_controller.get_attention_mode()
block_idx = _spike_controller.block_in_step
if attn_mode == "cached":
attn = _spike_controller.get_cached_attn(block_idx)
elif attn_mode == "spike":
# Spike: block-sparse Triton attention
attn_out = _spike_controller.attend(q, k, v)
attn = attn_out.transpose(1, 2).reshape(b, s, h)
_spike_controller.cache_attn(block_idx, attn)
else:
# Dense: ComfyUI's flash attention
attn = flux_attention(q, k, v, pe=None, mask=attn_mask,
transformer_options=transformer_options)
# Tick AFTER using block_in_step so indexing is correct
_spike_controller.tick()
if not attn.is_contiguous():
attn = attn.contiguous()
if attn.dtype != torch.float16:
attn = attn.to(dtype=torch.float16).contiguous()
# ── FINISH: L2 GEMM + fused gate+residual+bias in ONE call ──
result = torch.ops.flux_ext.ssb_finish(
x, attn, mlp, gate,
weights["l2w"], weights["l2w_scale"], weights["l2b"],
)
return result
def apply_patch():
try:
from comfy.ldm.flux.layers import SingleStreamBlock
if not hasattr(SingleStreamBlock, "_original_forward"):
SingleStreamBlock._original_forward = SingleStreamBlock.forward
# Try torch.compile on the dense inner path
use_compile = os.environ.get("FLUX_COMPILE", "0") == "1"
if use_compile:
try:
compiled_forward = torch.compile(patched_forward, mode="reduce-overhead", dynamic=True)
SingleStreamBlock.forward = compiled_forward
print("[flux_ext] torch.compile enabled (reduce-overhead, dynamic)")
except Exception as e:
print(f"[flux_ext] torch.compile failed ({e}), using uncompiled")
SingleStreamBlock.forward = patched_forward
else:
SingleStreamBlock.forward = patched_forward
mode = "torch.ops"
if _spike_controller.enabled:
mode += f" + SPIKE (switch={_spike_controller.switch_pct*100:.0f}%"
mode += f", cap={_spike_controller.event_cap_pct*100:.0f}%"
if _spike_controller.cache_enabled:
mode += " + step-cache"
mode += ")"
if use_compile:
mode += " + torch.compile"
print(f"[flux_ext] Patched SingleStreamBlock.forward ({mode})")
# Hook into ComfyUI's sampling to track generation start
_hook_sampling_start()
except ImportError as exc:
print(f"[flux_ext] Could not patch: {exc}")
except Exception as exc:
print(f"[flux_ext] Patch error: {exc}")
def _hook_sampling_start():
"""Hook into ComfyUI's sample function to call begin_generation() at each prompt."""
try:
import comfy.sample as sample_mod
# Store the REAL original only once
if not hasattr(sample_mod, "_flux_ext_original_sample"):
sample_mod._flux_ext_original_sample = sample_mod.sample
real_original = sample_mod._flux_ext_original_sample
def hooked_sample(*args, **kwargs):
steps = 20
sampler_name = ""
if len(args) > 2 and isinstance(args[2], int):
steps = args[2]
elif "steps" in kwargs:
steps = kwargs["steps"]
# comfy.sample.sample(model, noise, steps, cfg, sampler_name, ...)
if len(args) > 4:
sampler_name = str(args[4])
elif "sampler_name" in kwargs:
sampler_name = str(kwargs["sampler_name"])
_spike_controller.begin_generation(steps, sampler_name)
_pe_cache.clear()
evals = _spike_controller.total_evals
source = f"sampler={sampler_name}" if sampler_name else "estimated"
print(f"[flux_ext] Generation start: {steps} steps × {evals//max(1,steps)} evals/step = "
f"{evals} evals ({source}), "
f"spike={'ON' if _spike_controller.enabled else 'OFF'}")
return real_original(*args, **kwargs)
sample_mod.sample = hooked_sample
print("[flux_ext] Sampling hook installed on comfy.sample.sample")
except Exception as e:
print(f"[flux_ext] Could not hook sampling start: {e}")
+195
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@@ -0,0 +1,195 @@
from __future__ import annotations
import math
from typing import Any, Dict, Optional, Tuple
import torch
try:
import os
import warnings
os.environ['TRITON_DISABLE_LINE_INFO'] = '1'
with warnings.catch_warnings():
warnings.filterwarnings("ignore", category=UserWarning, module="triton")
import triton
import triton.language as tl
TRITON_AVAILABLE = True
except Exception:
TRITON_AVAILABLE = False
class _TritonStub:
def jit(self, fn=None, **kwargs):
if fn is None:
return lambda inner_fn: inner_fn
return fn
class _TLStub:
def __getattr__(self, name):
raise RuntimeError("Triton is required for spike attention.")
triton = _TritonStub()
tl = _TLStub()
BLOCK_SIZE = 32
def _ceil_div(x: int, y: int) -> int:
return (x + y - 1) // y
if TRITON_AVAILABLE:
@triton.jit
def _blocksparse_attention_kernel(
Q, K, V, Out,
BlockIndices, BlockCounts,
seq_len, head_dim, num_heads,
stride_q_batch, stride_q_head, stride_q_seq, stride_q_dim,
stride_k_batch, stride_k_head, stride_k_seq, stride_k_dim,
stride_v_batch, stride_v_head, stride_v_seq, stride_v_dim,
stride_o_batch, stride_o_head, stride_o_seq, stride_o_dim,
stride_idx_batch, stride_idx_head, stride_idx_qblock,
stride_counts_batch, stride_counts_head, stride_counts_qblock,
scale,
BLOCK_SIZE: tl.constexpr,
HEAD_DIM: tl.constexpr,
MAX_BLOCKS: tl.constexpr,
):
pid_bh = tl.program_id(0)
pid_qb = tl.program_id(1)
head = pid_bh % num_heads
batch = pid_bh // num_heads
q_start = pid_qb * BLOCK_SIZE
rows = q_start + tl.arange(0, BLOCK_SIZE)
cols = tl.arange(0, HEAD_DIM)
q_ptr = Q + batch * stride_q_batch + head * stride_q_head + rows[:, None] * stride_q_seq + cols[None, :] * stride_q_dim
q_mask = rows[:, None] < seq_len
q = tl.where(q_mask, tl.load(q_ptr, mask=q_mask, other=0.0), 0.0).to(tl.float32)
out_acc = tl.zeros((BLOCK_SIZE, HEAD_DIM), dtype=tl.float32)
m_i = tl.full((BLOCK_SIZE,), float("-inf"), dtype=tl.float32)
l_i = tl.zeros((BLOCK_SIZE,), dtype=tl.float32)
block_count = tl.load(BlockCounts + batch * stride_counts_batch + head * stride_counts_head + pid_qb * stride_counts_qblock, mask=True, other=0).to(tl.int32)
idx_ptr_base = BlockIndices + batch * stride_idx_batch + head * stride_idx_head + pid_qb * stride_idx_qblock
for block_pos in range(MAX_BLOCKS):
blk_in_range = block_pos < block_count
block_id = tl.load(idx_ptr_base + block_pos, mask=blk_in_range, other=-1)
valid = blk_in_range & (block_id >= 0)
k_rows = block_id * BLOCK_SIZE + tl.arange(0, BLOCK_SIZE)
kv_mask = (k_rows >= 0) & (k_rows < seq_len) & valid
k_ptr = K + batch * stride_k_batch + head * stride_k_head + k_rows[None, :] * stride_k_seq + cols[:, None] * stride_k_dim
v_ptr = V + batch * stride_v_batch + head * stride_v_head + k_rows[:, None] * stride_v_seq + cols[None, :] * stride_v_dim
k_block = tl.load(k_ptr, mask=kv_mask[None, :], other=0.0).to(tl.float32)
v_block = tl.load(v_ptr, mask=kv_mask[:, None], other=0.0).to(tl.float32)
scores = tl.dot(q, k_block) * scale
scores = tl.where(kv_mask[None, :], scores, float("-inf"))
scores = tl.where(q_mask, scores, float("-inf"))
m_new = tl.maximum(m_i, tl.max(scores, axis=1))
exp_scores = tl.where(kv_mask[None, :], tl.exp(scores - m_new[:, None]), 0.0)
l_new = l_i * tl.exp(m_i - m_new) + tl.sum(exp_scores, axis=1)
out_acc = (out_acc * (l_i * tl.exp(m_i - m_new))[:, None] + tl.dot(exp_scores, v_block)) / tl.maximum(l_new, 1e-6)[:, None]
m_i = m_new
l_i = l_new
out_ptr = Out + batch * stride_o_batch + head * stride_o_head + rows[:, None] * stride_o_seq + cols[None, :] * stride_o_dim
tl.store(out_ptr, out_acc, mask=q_mask)
def _launch_block_sparse_attention(q, k, v, block_indices, block_counts):
batch, heads, seq_len, head_dim = q.shape
num_blocks = _ceil_div(seq_len, BLOCK_SIZE)
max_blocks = block_indices.shape[-1]
out_fp32 = torch.zeros(batch, heads, seq_len, head_dim, dtype=torch.float32, device=q.device)
q_c, k_c, v_c = q.contiguous(), k.contiguous(), v.contiguous()
bi_c, bc_c = block_indices.contiguous(), block_counts.contiguous()
_blocksparse_attention_kernel[(batch * heads, num_blocks)](
Q=q_c, K=k_c, V=v_c, Out=out_fp32,
BlockIndices=bi_c, BlockCounts=bc_c,
seq_len=seq_len, head_dim=head_dim, num_heads=heads,
stride_q_batch=q_c.stride(0), stride_q_head=q_c.stride(1), stride_q_seq=q_c.stride(2), stride_q_dim=q_c.stride(3),
stride_k_batch=k_c.stride(0), stride_k_head=k_c.stride(1), stride_k_seq=k_c.stride(2), stride_k_dim=k_c.stride(3),
stride_v_batch=v_c.stride(0), stride_v_head=v_c.stride(1), stride_v_seq=v_c.stride(2), stride_v_dim=v_c.stride(3),
stride_o_batch=out_fp32.stride(0), stride_o_head=out_fp32.stride(1), stride_o_seq=out_fp32.stride(2), stride_o_dim=out_fp32.stride(3),
stride_idx_batch=bi_c.stride(0), stride_idx_head=bi_c.stride(1), stride_idx_qblock=bi_c.stride(2),
stride_counts_batch=bc_c.stride(0), stride_counts_head=bc_c.stride(1), stride_counts_qblock=bc_c.stride(2),
scale=1.0 / math.sqrt(head_dim),
BLOCK_SIZE=BLOCK_SIZE, HEAD_DIM=head_dim, MAX_BLOCKS=max_blocks,
)
return out_fp32 if q.dtype == torch.float32 else out_fp32.to(q.dtype)
else:
def _launch_block_sparse_attention(q, k, v, block_indices, block_counts):
raise RuntimeError("Triton unavailable — cannot run block-sparse attention.")
def has_triton() -> bool:
return TRITON_AVAILABLE and torch.cuda.is_available()
def attend_spike_triton(
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
*,
tau: float,
leak: float,
event_cap_pct: float,
state: Optional[Dict[str, torch.Tensor]] = None,
debug: Optional[Dict[str, Any]] = None,
) -> Tuple[torch.Tensor, Dict[str, Any]]:
batch, heads, seq_len, head_dim = q.shape
if seq_len == 0:
return torch.empty_like(q), {"telemetry": {"spike_events": 0}}
scale = head_dim ** -0.5
q_fp32 = q.to(torch.float32)
k_fp32 = k.to(torch.float32)
num_blocks = _ceil_div(seq_len, BLOCK_SIZE)
target_blocks = max(1, int(num_blocks * (int(seq_len * event_cap_pct) / max(1, seq_len))))
block_cap = max(1, min(num_blocks, target_blocks))
pad = num_blocks * BLOCK_SIZE - seq_len
if pad > 0:
q_fp32 = torch.nn.functional.pad(q_fp32, (0, 0, 0, pad))
k_fp32 = torch.nn.functional.pad(k_fp32, (0, 0, 0, pad))
q_blocks = q_fp32.view(batch, heads, num_blocks, BLOCK_SIZE, head_dim)
k_blocks = k_fp32.view(batch, heads, num_blocks, BLOCK_SIZE, head_dim)
q_rep = q_blocks.mean(dim=3)
k_rep = k_blocks.mean(dim=3)
block_scores = torch.matmul(q_rep, k_rep.transpose(-2, -1)) * scale
row_max = block_scores.max(dim=-1, keepdim=True)[0]
block_scores = torch.where(block_scores >= tau * row_max, block_scores, torch.full_like(block_scores, float('-inf')))
top_vals, top_idx = torch.topk(block_scores, k=block_cap, dim=-1)
valid = torch.isfinite(top_vals)
block_counts = valid.sum(dim=-1).to(torch.int32)
block_indices = torch.where(valid, top_idx, top_idx.new_full(top_idx.shape, -1))
output = _launch_block_sparse_attention(q, k, v, block_indices, block_counts)
avg_blocks = block_counts.float().mean().item()
kept_pct = 100.0 * (avg_blocks / max(1.0, float(num_blocks)))
tok_pct = (avg_blocks * BLOCK_SIZE) / max(1.0, float(seq_len))
return output, {
"block_indices": block_indices.detach(),
"block_counts": block_counts.detach(),
"telemetry": {
"backend": "block-topk",
"blocks_avg": avg_blocks,
"blocks_pct": kept_pct,
"block_cap": block_cap,
"flops_saved_pct": 100.0 * (1.0 - tok_pct),
"kept_events_pct": tok_pct * 100.0,
},
}
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#ifndef FLUX_STREAM_H
#define FLUX_STREAM_H
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <cuda_fp8.h>
#include <cublas_v2.h>
#include <cstdio>
#include <stdexcept>
#include <string>
namespace transformer {
constexpr int HIDDEN = 3072;
constexpr int HEADS = 24;
constexpr int HDIM = 128;
constexpr int FFDIM = 12288;
constexpr int MODDIM = 3 * HIDDEN;
constexpr int LIN1DIM = 3 * HIDDEN + FFDIM;
constexpr int LIN2DIM = HIDDEN + FFDIM;
constexpr float LN_EPS = 1e-6f;
constexpr float RMS_EPS = 1e-6f;
constexpr float ATT_SC = 0.0883883476f;
constexpr int FP8_MOD_W = 1;
constexpr int FP8_L1_W = 2;
constexpr int FP8_L2_W = 4;
#define CK(call) do { \
cudaError_t err__ = (call); \
if (err__ != cudaSuccess) { \
throw std::runtime_error(std::string("CUDA ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + cudaGetErrorString(err__)); \
} \
} while (0)
#define BK(call) do { \
cublasStatus_t st__ = (call); \
if (st__ != CUBLAS_STATUS_SUCCESS) { \
throw std::runtime_error(std::string("cuBLAS ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + std::to_string((int)st__)); \
} \
} while (0)
// Returns minimum workspace bytes needed for ssb_create
static inline size_t ssb_workspace_bytes(int batch, int seq) {
size_t rows = static_cast<size_t>(batch) * seq;
size_t b = static_cast<size_t>(batch);
size_t sz = 0;
// Each sub-buffer 256-byte aligned
#define ADDBUF(count, elem_size) \
sz = (sz + 255) & ~size_t(255); sz += (count) * (elem_size);
ADDBUF(b * HIDDEN, 2); // d_silu_
ADDBUF(b * MODDIM, 2); // d_mod_
ADDBUF(rows * HIDDEN, 2); // d_xmod_
ADDBUF(rows * LIN1DIM, 2); // d_l1o_
ADDBUF(rows * LIN2DIM, 1); // d_act_fp8_
ADDBUF(1, 4); // d_act_amax_
ADDBUF(1, 4); // d_act_scale_
ADDBUF(1, 4); // d_out_scale_
sz = (sz + 255) & ~size_t(255);
sz += 32ull << 20; // 32MB CUTLASS/cuBLAS workspace
#undef ADDBUF
return sz;
}
class SSBEngine {
public:
// workspace_buf: Python-allocated GPU memory (torch tensor .data_ptr())
// workspace_buf_size: must be >= ssb_workspace_bytes(batch, seq)
SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size);
~SSBEngine();
void prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const void* mod_w,
const float* mod_w_scale,
const half* mod_b,
const void* l1w,
const float* l1w_scale,
const half* l1b,
const half* qns,
const half* kns,
int fp8_mask,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream = 0);
void finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const void* l2w,
const float* l2w_scale,
const half* l2b,
int fp8_mask,
cudaStream_t stream = 0);
void forward(const half* d_x,
const half* d_vec,
half* d_out,
const half* d_pe,
const void* mod_w,
const float* mod_w_scale,
const half* mod_b,
const void* l1w,
const float* l1w_scale,
const half* l1b,
const void* l2w,
const float* l2w_scale,
const half* l2b,
const half* qns,
const half* kns,
int fp8_mask,
cudaStream_t stream = 0);
int batch() const { return B_; }
int seq() const { return S_; }
private:
int B_;
int S_;
cublasHandle_t cub_;
void* workspace_;
size_t workspace_bytes_;
half* d_silu_;
half* d_mod_;
half* d_xmod_;
half* d_l1o_;
__nv_fp8_e4m3* d_act_fp8_;
unsigned int* d_act_amax_;
float* d_act_scale_;
float* d_out_scale_;
};
} // namespace transformer
#endif // FLUX_STREAM_H
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# FLUXNATION
**Fused CUDA kernel for FLUX.1 image generation — RTX 4090 optimized.**
~9.3 seconds for 20 steps at 1024×1024. No other kernel does what this does.
---
## What it does
Three technologies fused into one ComfyUI custom node:
- **FP8 fused CUDA kernel** — replaces ComfyUI's SingleStreamBlock forward pass with a single `torch.ops` call. Modulation, L1 GEMM, QKV split, RoPE, L2 GEMM, gate+residual+bias all fused. Zero ctypes overhead.
- **Spike attention** — neuromorphic block-sparse Triton attention. After step 10/20, scores attention blocks by dot-product similarity and only computes the top 45%. Saves ~90% attention FLOPs on spike steps.
- **Step caching** — alternates between computing spike attention and replaying the cached output. Zero attention compute on every other spike step.
No fallbacks. If it breaks, it crashes — no silent quality degradation.
---
## Requirements
- Windows (tested) / Linux (should work)
- RTX 4090 (SM 8.9) — other Ampere/Ada cards may work but untested
- Python 3.10
- CUDA 12.x
- PyTorch 2.x with CUDA
- ComfyUI
- Visual Studio 2022 (for building the extension)
---
## Installation
### Step 1 — Clone and copy the custom node
```bash
git clone https://github.com/ULT7RA/cuda-kernels.git
```
Copy `FLUXNATION/custom_nodes/FLUXNATION/` into your ComfyUI custom nodes folder:
```
ComfyUI/custom_nodes/FLUXNATION/
```
### Step 2 — Build the CUDA extension
From the `FLUXNATION/` folder:
```bat
build_ext.bat
```
This requires:
- Visual Studio 2022 (with C++ workload)
- CUDA Toolkit 12.x
- Python 3.10
The build installs `flux_ext.cp310-win_amd64.pyd` into your Python site-packages automatically.
### Step 3 — Launch ComfyUI with spike enabled
Set these environment variables before launching:
```bat
set FLUX_SPIKE=1
set FLUX_SPIKE_SWITCH=0.50
set FLUX_SPIKE_CAP=0.45
set FLUX_SPIKE_TAU=0.05
set FLUX_SPIKE_CACHE=1
py -3.10 -s ComfyUI\main.py --windows-standalone-build --fast --dont-upcast-attention --disable-cuda-malloc --disable-mmap
```
Or use the included `run_nvidia_gpu_spike.bat`.
---
## ComfyUI Nodes
Four nodes appear under the **FLUXNATION** category:
| Node | Purpose |
|------|---------|
| `ULT7RAFLUX 👑` | Master node — all controls in one. Connect between Load Checkpoint and KSampler. |
| `FLUXNATION 🔥` | Pass-through — logs kernel status |
| `FLUXATTENHUT ⚡` | Configure spike params (switch %, cap %, tau) |
| `FLUXSPIKEY 🧠` | Toggle spike and step cache on/off |
**Basic workflow:**
```
Load Checkpoint → ULT7RAFLUX → KSampler
```
The kernel activates at ComfyUI startup regardless of whether the node is in your graph. The nodes give you live control without restarting.
---
## Environment Variables
| Variable | Default | Description |
|----------|---------|-------------|
| `FLUX_SPIKE` | `0` | Set to `1` to enable spike attention |
| `FLUX_SPIKE_SWITCH` | `0.35` | Fraction of steps before spike activates (`0.50` = step 10/20) |
| `FLUX_SPIKE_CAP` | `0.35` | Fraction of attention blocks to keep (`0.45` = keep top 45%) |
| `FLUX_SPIKE_TAU` | `0.05` | Block scoring threshold — lower keeps more blocks |
| `FLUX_SPIKE_CACHE` | `1` | Set to `1` to enable step caching |
| `FLUX_EXT_DISABLE` | `0` | Set to `1` to run stock ComfyUI (benchmarking) |
---
## How spike attention works
FLUX.1 has 38 SingleStreamBlocks per step. At step 10/20:
```
Steps 0–9: DENSE — full flash attention (image structure forms here)
Step 10: SPIKE — block-sparse Triton, fills cache for blocks 0–37
Step 11: CACHED — replay step 10 output, zero attention compute
Step 12: SPIKE — refill cache
Step 13: CACHED
...
Steps 18–19: DENSE — refinement tail
```
Block scoring uses real dot-product: `q_rep · k_rep^T` across heads. Top 45% of blocks by score get computed, rest are skipped. Quality is maintained because image structure is already established by step 10.
---
## Performance
RTX 4090 — FLUX.1-dev — 20 steps — 1024×1024:
| Mode | Time |
|------|------|
| Stock ComfyUI | ~13–14s |
| FLUXNATION (kernel only) | ~11s |
| FLUXNATION + spike + cache | **~9.3s** |
---
## File structure
```
FLUXNATION/
├── README.md
├── setup_ext.py — builds flux_ext CUDA extension
├── build_ext.bat — one-click build (Windows)
├── csrc/
│ ├── flux_ext.cpp — torch.ops registration
│ └── flux_ext_kernels.cu — FP8 GEMM + fused gate kernel
└── custom_nodes/
└── FLUXNATION/
├── __init__.py — ComfyUI loader + node definitions
├── FLUXPATCH.py — monkey-patch + spike controller
├── spike_attention.py — attend() router
└── spike_triton.py — Triton block-sparse kernel
```
---
## License
MIT
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#ifndef SINGLE_STREAM_BLOCK_H
#define SINGLE_STREAM_BLOCK_H
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <cuda_fp8.h>
#include <cublas_v2.h>
#include <cstdio>
#include <stdexcept>
#include <string>
namespace transformer {
constexpr int HIDDEN = 3072;
constexpr int HEADS = 24;
constexpr int HDIM = 128;
constexpr int FFDIM = 12288;
constexpr int MODDIM = 3 * HIDDEN;
constexpr int LIN1DIM = 3 * HIDDEN + FFDIM;
constexpr int LIN2DIM = HIDDEN + FFDIM;
constexpr float LN_EPS = 1e-6f;
constexpr float RMS_EPS = 1e-6f;
constexpr float ATT_SC = 0.0883883476f;
constexpr int FP8_MOD_W = 1;
constexpr int FP8_L1_W = 2;
constexpr int FP8_L2_W = 4;
#define CK(call) do { \
cudaError_t err__ = (call); \
if (err__ != cudaSuccess) { \
throw std::runtime_error(std::string("CUDA ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + cudaGetErrorString(err__)); \
} \
} while (0)
#define BK(call) do { \
cublasStatus_t st__ = (call); \
if (st__ != CUBLAS_STATUS_SUCCESS) { \
throw std::runtime_error(std::string("cuBLAS ") + __FILE__ + ":" + std::to_string(__LINE__) + ": " + std::to_string((int)st__)); \
} \
} while (0)
// Returns minimum workspace bytes needed for ssb_create
static inline size_t ssb_workspace_bytes(int batch, int seq) {
size_t rows = static_cast<size_t>(batch) * seq;
size_t b = static_cast<size_t>(batch);
size_t sz = 0;
// Each sub-buffer 256-byte aligned
#define ADDBUF(count, elem_size) \
sz = (sz + 255) & ~size_t(255); sz += (count) * (elem_size);
ADDBUF(b * HIDDEN, 2); // d_silu_
ADDBUF(b * MODDIM, 2); // d_mod_
ADDBUF(rows * HIDDEN, 2); // d_xmod_
ADDBUF(rows * LIN1DIM, 2); // d_l1o_
ADDBUF(rows * LIN2DIM, 1); // d_act_fp8_
ADDBUF(1, 4); // d_act_amax_
ADDBUF(1, 4); // d_act_scale_
ADDBUF(1, 4); // d_out_scale_
sz = (sz + 255) & ~size_t(255);
sz += 32ull << 20; // 32MB CUTLASS/cuBLAS workspace
#undef ADDBUF
return sz;
}
class SSBEngine {
public:
// workspace_buf: Python-allocated GPU memory (torch tensor .data_ptr())
// workspace_buf_size: must be >= ssb_workspace_bytes(batch, seq)
SSBEngine(int batch, int seq, void* workspace_buf, size_t workspace_buf_size);
~SSBEngine();
void prepare(const half* d_x,
const half* d_vec,
const half* d_pe,
const void* mod_w,
const float* mod_w_scale,
const half* mod_b,
const void* l1w,
const float* l1w_scale,
const half* l1b,
const half* qns,
const half* kns,
int fp8_mask,
half* d_q,
half* d_k,
half* d_v,
half* d_mlp,
half* d_gate,
cudaStream_t stream = 0);
void finish(const half* d_x,
const half* d_attn,
half* d_mlp,
const half* d_gate,
half* d_out,
const void* l2w,
const float* l2w_scale,
const half* l2b,
int fp8_mask,
cudaStream_t stream = 0);
void forward(const half* d_x,
const half* d_vec,
half* d_out,
const half* d_pe,
const void* mod_w,
const float* mod_w_scale,
const half* mod_b,
const void* l1w,
const float* l1w_scale,
const half* l1b,
const void* l2w,
const float* l2w_scale,
const half* l2b,
const half* qns,
const half* kns,
int fp8_mask,
cudaStream_t stream = 0);
int batch() const { return B_; }
int seq() const { return S_; }
private:
int B_;
int S_;
cublasHandle_t cub_;
void* workspace_;
size_t workspace_bytes_;
half* d_silu_;
half* d_mod_;
half* d_xmod_;
half* d_l1o_;
__nv_fp8_e4m3* d_act_fp8_;
unsigned int* d_act_amax_;
float* d_act_scale_;
float* d_out_scale_;
};
} // namespace transformer
#endif // SINGLE_STREAM_BLOCK_H
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"""
FLUXNATION — Fused CUDA kernel for FLUX.1 SingleStreamBlock.
Architecture: PyTorch C++ Extension via torch.ops (no ctypes)
- torch.ops.flux_ext.ssb_prepare: modulation + L1 GEMM + split QKV + RoPE
- torch.ops.flux_ext.ssb_finish: L2 GEMM + fused gate+residual+bias
Build: run build_ext.bat (or: py -3.10 setup_ext.py install)
"""
class FLUXNATION:
"""Main FLUXNATION kernel node. Pass-through MODEL — kernel is already active."""
CATEGORY = "FLUXNATION"
RETURN_TYPES = ("MODEL",)
RETURN_NAMES = ("model",)
FUNCTION = "apply"
@classmethod
def INPUT_TYPES(cls):
return {"required": {"model": ("MODEL",)}}
def apply(self, model):
from .FLUXPATCH import _spike_controller
spike = "SPIKE ON" if _spike_controller.enabled else "SPIKE OFF"
print(f"[FLUXNATION] FP8 fused CUDA kernel ACTIVE | {spike}")
return (model,)
class FLUXATTENHUT_Node:
"""Configure spike attention parameters."""
CATEGORY = "FLUXNATION"
RETURN_TYPES = ("MODEL",)
RETURN_NAMES = ("model",)
FUNCTION = "configure"
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"model": ("MODEL",),
"switch_pct": ("FLOAT", {"default": 0.50, "min": 0.1, "max": 0.9, "step": 0.05,
"tooltip": "Fraction of steps before spike activates (0.50 = step 10/20)"}),
"cap_pct": ("FLOAT", {"default": 0.45, "min": 0.1, "max": 0.9, "step": 0.05,
"tooltip": "Fraction of attention blocks to keep (0.45 = 45%)"}),
"tau": ("FLOAT", {"default": 0.05, "min": 0.01, "max": 0.5, "step": 0.01,
"tooltip": "Block scoring threshold — lower = more blocks kept"}),
}
}
def configure(self, model, switch_pct, cap_pct, tau):
from .FLUXPATCH import _spike_controller
_spike_controller.switch_pct = switch_pct
_spike_controller.event_cap_pct = cap_pct
_spike_controller.tau = tau
print(f"[FLUXATTENHUT] switch={switch_pct*100:.0f}% cap={cap_pct*100:.0f}% tau={tau}")
return (model,)
class FLUXSPIKEY_Node:
"""Enable or disable spike attention + step caching."""
CATEGORY = "FLUXNATION"
RETURN_TYPES = ("MODEL",)
RETURN_NAMES = ("model",)
FUNCTION = "configure"
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"model": ("MODEL",),
"spike": ("BOOLEAN", {"default": True, "tooltip": "Enable block-sparse spike attention"}),
"step_cache": ("BOOLEAN", {"default": True, "tooltip": "Cache attention output on alternating spike steps"}),
}
}
def configure(self, model, spike, step_cache):
from .FLUXPATCH import _spike_controller
_spike_controller.enabled = spike
_spike_controller.cache_enabled = step_cache
print(f"[FLUXSPIKEY] spike={'ON' if spike else 'OFF'} cache={'ON' if step_cache else 'OFF'}")
return (model,)
class ULT7RAFLUX:
"""Master status node — shows kernel state, spike config, and timing info."""
CATEGORY = "FLUXNATION"
RETURN_TYPES = ("MODEL",)
RETURN_NAMES = ("model",)
FUNCTION = "status"
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"model": ("MODEL",),
"spike": ("BOOLEAN", {"default": True}),
"step_cache": ("BOOLEAN", {"default": True}),
"switch_pct": ("FLOAT", {"default": 0.50, "min": 0.1, "max": 0.9, "step": 0.05}),
"cap_pct": ("FLOAT", {"default": 0.45, "min": 0.1, "max": 0.9, "step": 0.05}),
"tau": ("FLOAT", {"default": 0.05, "min": 0.01, "max": 0.5, "step": 0.01}),
}
}
def status(self, model, spike, step_cache, switch_pct, cap_pct, tau):
from .FLUXPATCH import _spike_controller
_spike_controller.enabled = spike
_spike_controller.cache_enabled = step_cache
_spike_controller.switch_pct = switch_pct
_spike_controller.event_cap_pct = cap_pct
_spike_controller.tau = tau
print(
f"[ULT7RAFLUX] FP8 fused kernel | "
f"spike={'ON' if spike else 'OFF'} | "
f"cache={'ON' if step_cache else 'OFF'} | "
f"switch={switch_pct*100:.0f}% cap={cap_pct*100:.0f}% tau={tau}"
)
return (model,)
NODE_CLASS_MAPPINGS = {
"FLUXNATION": FLUXNATION,
"FLUXATTENHUT": FLUXATTENHUT_Node,
"FLUXSPIKEY": FLUXSPIKEY_Node,
"ULT7RAFLUX": ULT7RAFLUX,
}
NODE_DISPLAY_NAME_MAPPINGS = {
"FLUXNATION": "FLUXNATION",
"FLUXATTENHUT": "FLUXATTENHUT",
"FLUXSPIKEY": "FLUXSPIKEY",
"ULT7RAFLUX": "ULT7RAFLUX",
}
_EXT_LOADED = False
def _patch_safetensor_loading():
"""Fix Windows mmap access violation in safetensors loading.
PyTorch 2.5.x + safetensors safe_open() on Windows triggers access violations
when memory-mapping large files (>10GB). This patches ComfyUI's load_torch_file
to use safetensors.torch.load_file() which loads the full file without mmap.
"""
import sys
if sys.platform != "win32":
return
try:
import comfy.utils as comfy_utils
import safetensors.torch
import torch
_original_load = comfy_utils.load_torch_file
def _read_safetensor_streaming(path, target_device='cpu'):
"""Stream-load a safetensor file without mmap or full-file buffering.
Reads the header to get tensor metadata, then reads each tensor
individually from disk into a pre-allocated torch tensor.
"""
import struct, json, numpy as np
dtype_map = {
'F16': (torch.float16, 2),
'BF16': (torch.bfloat16, 2),
'F32': (torch.float32, 4),
'F64': (torch.float64, 8),
'I8': (torch.int8, 1),
'I16': (torch.int16, 2),
'I32': (torch.int32, 4),
'I64': (torch.int64, 8),
'U8': (torch.uint8, 1),
'BOOL': (torch.bool, 1),
'F8_E4M3': (getattr(torch, 'float8_e4m3fn', torch.uint8), 1),
'F8_E5M2': (getattr(torch, 'float8_e5m2', torch.uint8), 1),
}
np_dtype_map = {
'F16': np.float16, 'BF16': np.void, 'F32': np.float32,
'F64': np.float64, 'I8': np.int8, 'I16': np.int16,
'I32': np.int32, 'I64': np.int64, 'U8': np.uint8,
'BOOL': np.bool_,
}
with open(path, 'rb') as f:
header_size = struct.unpack('<Q', f.read(8))[0]
header_bytes = f.read(header_size)
data_offset = 8 + header_size
header = json.loads(header_bytes)
metadata = header.pop('__metadata__', {})
sd = {}
for name, info in header.items():
dtype_str = info['dtype']
shape = info['shape']
offsets = info['data_offsets']
start, end = offsets[0], offsets[1]
nbytes = end - start
torch_dtype, elem_size = dtype_map.get(dtype_str, (torch.float32, 4))
f.seek(data_offset + start)
raw = f.read(nbytes)
if dtype_str == 'BF16':
# numpy doesn't support bfloat16 — read as uint16 then view
arr = np.frombuffer(raw, dtype=np.uint16).reshape(shape)
t = torch.from_numpy(arr.copy()).view(torch.bfloat16)
elif dtype_str in ('F8_E4M3', 'F8_E5M2'):
arr = np.frombuffer(raw, dtype=np.uint8).reshape(shape)
t = torch.from_numpy(arr.copy()).view(torch_dtype)
else:
np_dt = np_dtype_map.get(dtype_str, np.float32)
arr = np.frombuffer(raw, dtype=np_dt).reshape(shape)
t = torch.from_numpy(arr.copy())
if target_device != 'cpu':
t = t.to(device=target_device)
sd[name] = t
return sd, metadata
def _safe_load_torch_file(ckpt, safe_load=False, device=None, return_metadata=False):
if device is None:
device = torch.device("cpu")
if not ckpt.lower().endswith((".safetensors", ".sft")):
return _original_load(ckpt, safe_load=safe_load, device=device,
return_metadata=return_metadata)
import os
size_gb = os.path.getsize(ckpt) / (1024**3)
# Only use streaming loader for large files (>1GB) to avoid mmap crash
if size_gb > 1.0:
print(f"[FLUXNATION] Loading {os.path.basename(ckpt)} ({size_gb:.1f} GB) via streaming loader")
try:
import time
t0 = time.time()
sd, metadata = _read_safetensor_streaming(ckpt, device.type)
elapsed = time.time() - t0
print(f"[FLUXNATION] Loaded {len(sd)} tensors in {elapsed:.1f}s (streaming, no-mmap)")
if return_metadata:
return sd, metadata
return sd
except Exception as e:
print(f"[FLUXNATION] Streaming load failed ({e}), falling back to original")
return _original_load(ckpt, safe_load=safe_load, device=device,
return_metadata=return_metadata)
else:
return _original_load(ckpt, safe_load=safe_load, device=device,
return_metadata=return_metadata)
comfy_utils.load_torch_file = _safe_load_torch_file
print("[FLUXNATION] Patched safetensor loading (non-mmap, Windows crash fix)")
except Exception as e:
print(f"[FLUXNATION] Could not patch safetensor loading: {e}")
def _try_load_extension():
"""Try to import the compiled flux_ext extension."""
global _EXT_LOADED
try:
import flux_ext # noqa: F401 — triggers TORCH_LIBRARY registration
_EXT_LOADED = True
print("[FLUXNATION] Loaded PyTorch C++ extension successfully")
except ImportError:
import torch
import os
root = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
for candidate in [
os.path.join(root, "flux_ext.pyd"),
os.path.join(root, "flux_ext.so"),
]:
if os.path.exists(candidate):
try:
torch.ops.load_library(candidate)
_EXT_LOADED = True
print(f"[FLUXNATION] Loaded from {candidate}")
break
except Exception as e:
print(f"[FLUXNATION] Failed to load {candidate}: {e}")
if not _EXT_LOADED:
print("[FLUXNATION] Extension not found. Run build_ext.bat to compile.")
return False
_register_fake_kernels()
return True
def _register_fake_kernels():
"""Register Meta/FakeTensor implementations for torch.compile."""
import torch
if not hasattr(torch, 'library') or not hasattr(torch.library, 'register_fake'):
print("[FLUXNATION] torch.library.register_fake not available, skipping")
return
try:
@torch.library.register_fake("flux_ext::ssb_prepare")
def _fake_prepare(x, vec, pe, mod_w, mod_w_scale, mod_b,
l1w, l1w_scale, l1b, qns, kns):
B, S = x.size(0), x.size(1)
q = torch.empty([B, 24, S, 128], dtype=torch.float16, device=x.device)
k = torch.empty([B, 24, S, 128], dtype=torch.float16, device=x.device)
v = torch.empty([B, 24, S, 128], dtype=torch.float16, device=x.device)
mlp = torch.empty([B, S, 12288], dtype=torch.float16, device=x.device)
gate = torch.empty([B, 3072], dtype=torch.float16, device=x.device)
return (q, k, v, mlp, gate)
@torch.library.register_fake("flux_ext::ssb_finish")
def _fake_finish(x, attn, mlp, gate, l2w, l2w_scale, l2b):
return torch.empty_like(x, dtype=torch.bfloat16)
@torch.library.register_fake("flux_ext::ssb_cleanup")
def _fake_cleanup():
return
except Exception as e:
print(f"[FLUXNATION] Warning: could not register fake kernels: {e}")
# ── Initialization: patch safetensor loading + load extension ──
import os as _os
_patch_safetensor_loading()
if _os.environ.get("FLUX_EXT_DISABLE", "0") == "1":
print("[FLUXNATION] DISABLED by FLUX_EXT_DISABLE env var (stock mode)")
elif _try_load_extension():
from .FLUXPATCH import apply_patch
apply_patch()
else:
print("[FLUXNATION] DISABLED — extension not found. Run build_ext.bat.")
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@echo off
setlocal
REM Use VS 2022 (CUDA 12.8 supports MSVC 14.3x from VS 2022, not MSVC 14.5x from VS 2025)
set "VSVARS=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat"
if not exist "%VSVARS%" (
echo [flux_ext] ERROR: VS 2022 vcvars64.bat not found
exit /b 1
)
call "%VSVARS%" || exit /b 1
set DISTUTILS_USE_SDK=1
echo [flux_ext] Building PyTorch C++ extension with VS 2022 + CUDA 12.8...
py -3.10 setup_ext.py install
if errorlevel 1 (
echo [flux_ext] Build FAILED
exit /b 1
)
echo [flux_ext] Build succeeded! flux_ext is now installed.
echo [flux_ext] Restart ComfyUI to use the new torch.ops path.
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/*
* flux_ext_kernels.cu — PyTorch C++ extension for FLUXNATION
*
* Wraps SSBEngine (from flux_opt.cu) as torch.ops custom operators.
* Adds fused gate+residual+bias kernel to eliminate Python-side overhead.
*/
#include <torch/extension.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
// SSBEngine class + constants from existing code
#include "SINGLE_STREAM_BLOCK.H"
#include <unordered_map>
#include <memory>
#include <mutex>
using namespace transformer;
// =========================================================================
// Vectorized load/store types (same as flux_opt.cu but local to this TU)
// =========================================================================
union VecBF16_8_ext {
float4 f4;
__nv_bfloat16 b[8];
};
union VecHalf8_ext {
float4 f4;
half h[8];
};
// =========================================================================
// NEW: Fused gate + residual + L2-bias kernel
//
// result[b,s,h] = x[b,s,h] + gate[b,h] * (l2_out[b,s,h] + l2b[h])
//
// All reads/writes vectorized 8-wide. Eliminates 5 intermediate float32
// tensors that the Python path previously created per block.
// =========================================================================
__global__ void gate_residual_bias_bf16_kernel(
const __nv_bfloat16* __restrict__ d_l2out, // [rows, HIDDEN] L2 GEMM output (bf16)
const __nv_bfloat16* __restrict__ d_x, // [rows, HIDDEN] original input / residual (bf16)
const half* __restrict__ d_gate, // [B, HIDDEN] gate values (fp16)
const half* __restrict__ l2b, // [HIDDEN] L2 bias (fp16)
__nv_bfloat16* __restrict__ d_result, // [rows, HIDDEN] output (bf16)
int S,
int total_elems)
{
int base = (blockIdx.x * blockDim.x + threadIdx.x) * 8;
if (base >= total_elems) return;
int row = base / HIDDEN;
int col = base % HIDDEN;
int batch = row / S;
// Vectorized loads
VecBF16_8_ext out_v = *reinterpret_cast<const VecBF16_8_ext*>(&d_l2out[base]);
VecBF16_8_ext x_v = *reinterpret_cast<const VecBF16_8_ext*>(&d_x[base]);
VecHalf8_ext gate_v = *reinterpret_cast<const VecHalf8_ext*>(&d_gate[batch * HIDDEN + col]);
VecHalf8_ext bias_v = *reinterpret_cast<const VecHalf8_ext*>(&l2b[col]);
VecBF16_8_ext result_v;
#pragma unroll
for (int i = 0; i < 8; i++) {
float l2_f = __bfloat162float(out_v.b[i]);
float x_f = __bfloat162float(x_v.b[i]);
float g_f = __half2float(gate_v.h[i]);
float b_f = __half2float(bias_v.h[i]);
result_v.b[i] = __float2bfloat16(x_f + g_f * (l2_f + b_f));
}
*reinterpret_cast<VecBF16_8_ext*>(&d_result[base]) = result_v;
}
// =========================================================================
// Global engine cache — keyed by (device, batch, seq_len)
// =========================================================================
struct EngineEntry {
std::unique_ptr<SSBEngine> engine;
at::Tensor workspace; // prevents deallocation
};
static std::unordered_map<int64_t, EngineEntry> g_engine_cache;
static std::mutex g_engine_mutex;
static int64_t make_engine_key(int device, int batch, int seq) {
return (int64_t)device * 1000000000LL + (int64_t)batch * 1000000LL + seq;
}
static SSBEngine* get_or_create_engine(int batch, int seq, at::Device device) {
int dev_idx = device.index();
int64_t key = make_engine_key(dev_idx, batch, seq);
std::lock_guard<std::mutex> lock(g_engine_mutex);
auto it = g_engine_cache.find(key);
if (it != g_engine_cache.end()) {
return it->second.engine.get();
}
// Create new engine
at::cuda::CUDAGuard guard(device);
size_t ws_bytes = ssb_workspace_bytes(batch, seq);
auto ws_tensor = at::empty({(int64_t)ws_bytes}, at::TensorOptions().dtype(at::kByte).device(device));
auto engine = std::make_unique<SSBEngine>(batch, seq, ws_tensor.data_ptr(), ws_bytes);
auto* ptr = engine.get();
EngineEntry entry;
entry.engine = std::move(engine);
entry.workspace = ws_tensor;
g_engine_cache[key] = std::move(entry);
fprintf(stderr, "[flux_ext] Created engine B=%d S=%d ws=%.1fMB dev=%d\n",
batch, seq, ws_bytes / (1024.0 * 1024.0), dev_idx);
fflush(stderr);
return ptr;
}
// =========================================================================
// torch.ops implementation: ssb_prepare
//
// Runs: silu → mod GEMM → layernorm_mod → linear1 GEMM → split_qkv →
// copy_mlp → extract_gate → rmsnorm → rope
//
// Returns: (q, k, v, mlp, gate)
// =========================================================================
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, // [B, S, 3072] bf16
at::Tensor vec, // [B, 3072] or [B, 1, 3072] fp16
at::Tensor pe, // [S, 64, 2] fp16 (pre-converted)
at::Tensor mod_w, // FP8 [MODDIM, HIDDEN]
at::Tensor mod_w_scale, // float32 [1]
at::Tensor mod_b, // fp16 [MODDIM]
at::Tensor l1w, // FP8 [LIN1DIM, HIDDEN]
at::Tensor l1w_scale, // float32 [1]
at::Tensor l1b, // fp16 [LIN1DIM]
at::Tensor qns, // fp16 [128]
at::Tensor kns) // fp16 [128]
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
// Ensure correct dtypes and contiguity
auto x_bf16 = x.to(at::kBFloat16).contiguous();
auto vec_fp16 = vec.dim() == 3 ? vec.squeeze(1).to(at::kHalf).contiguous()
: vec.to(at::kHalf).contiguous();
auto pe_fp16 = pe.to(at::kHalf).contiguous();
// Allocate output tensors
auto opts_fp16 = at::TensorOptions().dtype(at::kHalf).device(device);
auto q = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto k = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto v = at::empty({B, HEADS, S, HDIM}, opts_fp16);
auto mlp = at::empty({B, S, FFDIM}, opts_fp16);
auto gate = at::empty({B, HIDDEN}, opts_fp16);
// Get or create engine (manages workspace internally)
SSBEngine* engine = get_or_create_engine(B, S, device);
// Call prepare — all pointer casts match existing kernel expectations
engine->prepare(
reinterpret_cast<const half*>(x_bf16.data_ptr()),
reinterpret_cast<const half*>(vec_fp16.data_ptr()),
reinterpret_cast<const half*>(pe_fp16.data_ptr()),
mod_w.data_ptr(), // FP8 weights (void*)
mod_w_scale.defined() ? reinterpret_cast<const float*>(mod_w_scale.data_ptr()) : nullptr,
reinterpret_cast<const half*>(mod_b.data_ptr()),
l1w.data_ptr(), // FP8 weights (void*)
l1w_scale.defined() ? reinterpret_cast<const float*>(l1w_scale.data_ptr()) : nullptr,
reinterpret_cast<const half*>(l1b.data_ptr()),
reinterpret_cast<const half*>(qns.data_ptr()),
reinterpret_cast<const half*>(kns.data_ptr()),
7, // fp8_mask = all FP8
reinterpret_cast<half*>(q.data_ptr()),
reinterpret_cast<half*>(k.data_ptr()),
reinterpret_cast<half*>(v.data_ptr()),
reinterpret_cast<half*>(mlp.data_ptr()),
reinterpret_cast<half*>(gate.data_ptr()),
stream);
return std::make_tuple(q, k, v, mlp, gate);
}
// =========================================================================
// torch.ops implementation: ssb_finish
//
// Runs: gelu → concat → L2 GEMM → FUSED gate+residual+bias
//
// Returns: result [B, S, 3072] bf16
// =========================================================================
at::Tensor ssb_finish_impl(
at::Tensor x, // [B, S, 3072] bf16 — original input for residual
at::Tensor attn, // [B, S, 3072] fp16 — attention output
at::Tensor mlp, // [B, S, 12288] fp16 — MLP intermediate (pre-GELU)
at::Tensor gate, // [B, 3072] fp16 — gate values
at::Tensor l2w, // FP8 [HIDDEN, LIN2DIM]
at::Tensor l2w_scale, // float32 [1]
at::Tensor l2b) // fp16 [3072] — L2 bias
{
TORCH_CHECK(x.is_cuda(), "x must be CUDA");
TORCH_CHECK(x.dim() == 3 && x.size(2) == HIDDEN, "x must be [B, S, 3072]");
int B = x.size(0);
int S = x.size(1);
int rows = B * S;
auto device = x.device();
at::cuda::CUDAGuard guard(device);
auto stream = at::cuda::getCurrentCUDAStream(device.index());
auto x_bf16 = x.to(at::kBFloat16).contiguous();
auto attn_fp16 = attn.to(at::kHalf).contiguous();
// mlp is already fp16 from prepare — ensure contiguous
auto mlp_c = mlp.contiguous();
auto gate_c = gate.contiguous();
auto l2b_c = l2b.to(at::kHalf).contiguous();
// Temp buffer for L2 GEMM output (bf16) — ATen caching allocator makes this free
auto l2_out = at::empty({B, S, HIDDEN}, at::TensorOptions().dtype(at::kBFloat16).device(device));
SSBEngine* engine = get_or_create_engine(B, S, device);
// Call existing finish() — does gelu, concat, L2 GEMM
// NOTE: finish() FP8 path writes bf16 to d_out, does NOT add bias/gate/residual
engine->finish(
reinterpret_cast<const half*>(x_bf16.data_ptr()), // d_x (bf16 in half*)
reinterpret_cast<const half*>(attn_fp16.data_ptr()), // d_attn
reinterpret_cast<half*>(mlp_c.data_ptr()), // d_mlp (in/out)
reinterpret_cast<const half*>(gate_c.data_ptr()), // d_gate
reinterpret_cast<half*>(l2_out.data_ptr()), // d_out (bf16)
l2w.data_ptr(), // FP8 weights
l2w_scale.defined() ? reinterpret_cast<const float*>(l2w_scale.data_ptr()) : nullptr,
reinterpret_cast<const half*>(l2b_c.data_ptr()), // l2b (unused by finish FP8 path)
7, // fp8_mask = all FP8
stream);
// FUSED: gate + residual + L2 bias in one kernel
// result = x + gate * (l2_out + l2b)
auto result = at::empty_like(x_bf16);
int total_elems = rows * HIDDEN;
int threads = 256;
int blocks = (total_elems + threads * 8 - 1) / (threads * 8);
gate_residual_bias_bf16_kernel<<<blocks, threads, 0, stream>>>(
reinterpret_cast<const __nv_bfloat16*>(l2_out.data_ptr()),
reinterpret_cast<const __nv_bfloat16*>(x_bf16.data_ptr()),
reinterpret_cast<const half*>(gate_c.data_ptr()),
reinterpret_cast<const half*>(l2b_c.data_ptr()),
reinterpret_cast<__nv_bfloat16*>(result.data_ptr()),
S,
total_elems);
return result;
}
// =========================================================================
// Cleanup function — destroys all cached engines
// =========================================================================
void ssb_cleanup_impl() {
std::lock_guard<std::mutex> lock(g_engine_mutex);
g_engine_cache.clear();
fprintf(stderr, "[flux_ext] All engines destroyed\n");
fflush(stderr);
}
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/*
* flux_ext.cpp — TORCH_LIBRARY registration for FLUXNATION
*
* Registers ssb_prepare and ssb_finish as torch.ops.flux_ext.* custom ops.
* This eliminates ctypes overhead and enables torch.compile compatibility.
*/
#include <torch/extension.h>
#include <ATen/ATen.h>
// Forward declarations of CUDA implementations (in flux_ext_kernels.cu)
std::tuple<at::Tensor, at::Tensor, at::Tensor, at::Tensor, at::Tensor>
ssb_prepare_impl(
at::Tensor x, at::Tensor vec, at::Tensor pe,
at::Tensor mod_w, at::Tensor mod_w_scale, at::Tensor mod_b,
at::Tensor l1w, at::Tensor l1w_scale, at::Tensor l1b,
at::Tensor qns, at::Tensor kns);
at::Tensor ssb_finish_impl(
at::Tensor x, at::Tensor attn, at::Tensor mlp, at::Tensor gate,
at::Tensor l2w, at::Tensor l2w_scale, at::Tensor l2b);
void ssb_cleanup_impl();
// =========================================================================
// Op schema definitions
// =========================================================================
TORCH_LIBRARY(flux_ext, m) {
m.def("ssb_prepare("
"Tensor x, Tensor vec, Tensor pe, "
"Tensor mod_w, Tensor mod_w_scale, Tensor mod_b, "
"Tensor l1w, Tensor l1w_scale, Tensor l1b, "
"Tensor qns, Tensor kns"
") -> (Tensor, Tensor, Tensor, Tensor, Tensor)");
m.def("ssb_finish("
"Tensor x, Tensor attn, Tensor mlp, Tensor gate, "
"Tensor l2w, Tensor l2w_scale, Tensor l2b"
") -> Tensor");
m.def("ssb_cleanup() -> ()");
}
// =========================================================================
// CUDA backend implementations
// =========================================================================
TORCH_LIBRARY_IMPL(flux_ext, CUDA, m) {
m.impl("ssb_prepare", &ssb_prepare_impl);
m.impl("ssb_finish", &ssb_finish_impl);
m.impl("ssb_cleanup", &ssb_cleanup_impl);
}
// =========================================================================
// Python module init (required for import flux_ext to work)
// =========================================================================
PYBIND11_MODULE(flux_ext, m) {
m.doc() = "FLUXNATION: Fused CUDA kernels for FLUX.1 SingleStreamBlock";
}
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"""
ComfyUI Manager install script.
Runs build_ext.bat to compile the CUDA extension after clone.
Requires: CUDA Toolkit 12.x, Visual Studio 2022 (Windows) or gcc/nvcc (Linux).
"""
import subprocess
import sys
import os
node_dir = os.path.dirname(os.path.abspath(__file__))
if sys.platform == "win32":
build_script = os.path.join(node_dir, "build_ext.bat")
if os.path.exists(build_script):
print("[FLUXNATION] Building CUDA extension...")
result = subprocess.run([build_script], cwd=node_dir, shell=True)
if result.returncode == 0:
print("[FLUXNATION] Build succeeded.")
else:
print("[FLUXNATION] Build failed. Install CUDA Toolkit 12.x and Visual Studio 2022, then run build_ext.bat manually.")
else:
print("[FLUXNATION] build_ext.bat not found.")
else:
print("[FLUXNATION] Linux build: run 'python setup_ext.py install' from the node directory.")
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set CUDA_LAUNCH_BLOCKING=0
set TORCH_CUDNN_V8_API_ENABLED=1
set FLUX_SPIKE=1
set FLUX_SPIKE_SWITCH=0.50
set FLUX_SPIKE_CAP=0.45
set FLUX_SPIKE_TAU=0.05
set FLUX_SPIKE_CACHE=1
py -3.10 -s ComfyUI\main.py --windows-standalone-build --fast --dont-upcast-attention --disable-cuda-malloc --disable-mmap
pause
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@echo off
:: FLUXNATION Low-VRAM Profile
:: For GPUs with 8-12GB VRAM (RTX 3060, 3070, etc.)
:: Aggressive spike + step caching to minimize attention memory
:: Quality trade-off is real but generation is POSSIBLE where it wasn't before
set CUDA_LAUNCH_BLOCKING=0
set TORCH_CUDNN_V8_API_ENABLED=1
set FLUX_SPIKE=1
set FLUX_SPIKE_SWITCH=0.15
set FLUX_SPIKE_CAP=0.20
set FLUX_SPIKE_TAU=0.03
set FLUX_SPIKE_CACHE=1
py -3.10 -s ComfyUI\main.py --windows-standalone-build --fast --dont-upcast-attention --disable-cuda-malloc --lowvram
pause
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"""
Build script for flux_ext PyTorch C++/CUDA extension.
Usage:
py -3.10 setup_ext.py install
This compiles the CUTLASS FP8 kernels (from flux_opt.cu) into a proper
PyTorch extension, eliminating all ctypes overhead.
"""
import os
# Use CUDA 12.8 (compatible with PyTorch 2.5.1 which was built with CUDA 12.1)
os.environ["CUDA_HOME"] = r"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.8"
os.environ["CUDA_PATH"] = os.environ["CUDA_HOME"]
from setuptools import setup
from torch.utils.cpp_extension import CUDAExtension, BuildExtension
ROOT = os.path.dirname(os.path.abspath(__file__))
setup(
name="flux_ext",
ext_modules=[
CUDAExtension(
name="flux_ext",
sources=[
os.path.join(ROOT, "csrc", "FLUXPATCH.cpp"),
os.path.join(ROOT, "csrc", "FLUXNATION.cu"),
os.path.join(ROOT, "flux_opt.cu"),
],
include_dirs=[
ROOT, # SINGLE_STREAM_BLOCK.H
os.path.join(ROOT, "cutlass", "include"), # CUTLASS headers
],
extra_compile_args={
"cxx": ["/O2", "/std:c++17", "/EHsc", "/MD"],
"nvcc": [
"-O3",
"-std=c++17",
"-arch=sm_89",
"-DFLUX_TORCH_EXT=1",
"--allow-unsupported-compiler",
"-diag-suppress=20013",
"-diag-suppress=20015",
"-Xcompiler", "/MD",
"-Xcompiler", "/EHsc",
"-Xcompiler", "/Zc:preprocessor",
],
},
libraries=["cublas"],
)
],
cmdclass={"build_ext": BuildExtension},
)