The wan-t2v perf lane intermittently runs ~1.7x slow on packed Modal
hosts (TE pinned at 3.595s vs the 2.03s healthy cluster, DiT +58-80%,
GPU clocks at full boost): host CPU contention that cpu=8/16
reservations cannot isolate. 9 of the last ~11 full suites redded only
on this lane. A perf gate must never fail a PR on a measurement taken
on a degraded host (review r30, option a).
The harness now runs a ~1.5s host CPU probe (single-thread pure-Python
loop, gated axis; 8-thread torch matmul, informational) once per pytest
process and stores host_cpu_score on every record. The comparator emits
HOST_BELOW_PROFILE when the score is under the calibrated floor
(PERF_HOST_CPU_MIN_SCORE, default 0.75): gating is skipped loudly, CI
passes, and the record can never seed a baseline. Records without a
score gate normally.
Calibrated against five fresh perf-lane containers (L40S:2 cpu=8):
healthy hosts score 0.97-1.17, packed-host projections 0.54-0.73;
sampled data and recalibration procedure documented in host_probe.py.
Stacked on maint/perf-comparator-statuses (f46c9e61).
SolitaryThinker
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