cuBLAS GEMM calls inside CUDA-graph capture regions cause
CUDA_ERROR_STREAM_CAPTURE_INVALIDATED on first use of new (m,n,k)
shapes. The mega-graph was silently failing → fast-path replay was
a NO-OP → sps stayed at ~10.
Phase 1 — DQN distributional Q head:
- New crates/ml-alpha/cuda/dqn_q_head_fwd_bwd.cu (3 kernels)
- Removed cuBLAS field + gemm_f32 helper from dqn.rs
Phase 2 — IQN ensemble heads:
- New crates/ml-alpha/cuda/rl_iqn_matmul.cu (3 kernels)
- Removed cuBLAS field from iqn.rs
Phase 3 — Mamba2 SKIPPED: workspace pre-warms during 65+ eager
warmup steps before mega-graph capture.
Local smoke (RTX 3050 Ti, b=128, 500 steps):
- Mega-graph captures cleanly at step 67
- 8.9 sps avg, 11 sps peak post-capture (GPU-bound on mobile GPU)
- l_q=0.024 (healthy), l_pi rising, V converging
- Production L40S should see full mega-graph speedup now
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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