[perf] Sequential MiniMax H3 start with GPU-direct DiT load (#1793)

Co-authored-by: Aryan Kumar <aryan5v@users.noreply.github.com>

examples/inference/basic/README.md

@@ -118,7 +118,7 @@ python examples/inference/basic/basic_fasth3.py \
   --warmup-seed 999
 ```
 
-`all` enables the inference-only H3 fusions and regional compile. Both can change floating-point operation order, so this is a report-only performance profile rather than an exact-parity route. Use `--profile strict` to disable the H3 fusions while preserving regional compile, or `--profile strict --no-inference-torch-compile` for the eager strict route. Individual `--no-*` switches are available for portability and attribution; in particular, use `--vsa-kernel triton --no-fa4` if the Blackwell kernels are unavailable. The script preserves the warmup and each measured video under distinct paths, then prints per-request wall time plus a warmup-excluded median.
+`all` enables the inference-only H3 fusions and regional compile. Both can change floating-point operation order, so this is a report-only performance profile rather than an exact-parity route. Use `--profile strict` to disable the H3 fusions while preserving regional compile, or `--profile strict --no-inference-torch-compile` for the eager strict route. Individual `--no-*` switches are available for portability and attribution; in particular, use `--vsa-kernel triton --no-fa4` if the Blackwell kernels are unavailable. `--h3-sequential-load` / `--no-h3-sequential-load` override the auto split that releases Qwen3-VL before DiT/VAE load (on by default on GB10, off on discrete GPUs). The script preserves the warmup and each measured video under distinct paths, then prints per-request wall time plus a warmup-excluded median.
 
 One script covers each validated duration; regional compile is the fastest
 measured DiT route for all three:

examples/inference/basic/basic_fasth3.py

@@ -99,6 +99,11 @@ def build_parser(description: str | None = None) -> argparse.ArgumentParser:
                         action=argparse.BooleanOptionalAction,
                         default=True,
                         help="round-robin VAE temporal chunks across sequence-parallel ranks")
+    parser.add_argument("--h3-sequential-load",
+                        action=argparse.BooleanOptionalAction,
+                        default=None,
+                        help="encode with Qwen3-VL, release it, then load DiT/VAEs. Default auto: on for "
+                        "unified-memory devices (GB10), off on discrete GPUs")
     parser.add_argument("--replicated-dit",
                         action=argparse.BooleanOptionalAction,
                         default=True,
@@ -229,6 +234,8 @@ def build_generator_config(args: argparse.Namespace) -> GeneratorConfig:
         "vae_parallel_decode": args.parallel_vae,
         "vae_parallel_decode_strategy": "gather",
     }
+    if args.h3_sequential_load is not None:
+        experimental["h3_sequential_load"] = args.h3_sequential_load
     if use_vsa:
         experimental.update({
             "VSA_sparsity": args.vsa_sparsity,