c17e517e9e
From reading cccl_upstream/cub/cub/device/dispatch/tuning/tuning_transform.cuh:
1. BI-V100 can only use prefetch and vectorized algorithms.
ldgsts (SM80+ cp.async) and ublkcp (SM90+ bulk copy) are NVIDIA-only.
2. bytes_in_flight only affects the PREFETCH path. For vllm's
contiguous fp16 element-wise ops (RMSNorm/SiLU/RoPE), the
VECTORIZED path is selected, where items_per_thread is fixed
at compile time, not derived from bytes_in_flight.
3. CCCL's cc_to_min_bytes_in_flight: B200=64KB, H100=48KB, A100=16KB,
V100=12KB. Our 64KB matches B200 level (56 GB/s/SM ≈ B200).
4. Bench result alg=1 confirms vectorized path is used on BI-V100.
The vectorized default {256, 8, 4} matches the benchmark winner.
Source: cccl_upstream/cub/cub/device/dispatch/tuning/tuning_transform.cuh