e36da2efa9
Two findings from reading CCCL source code:
1. single_pass_scan_operators.cuh: delay() has GridThreshold=500 gate.
BI-V100 scan launches ~12 blocks (100K elements / tile_size).
12 < 500, so ALL delay policies collapse to __threadfence_block().
Conclusion: delay_ns, delay_l2w, delay_algorithm are IRRELEVANT
on BI-V100. Only threads/items/load/scan algorithms matter.
2. summary_statistics.cu compound reduce pattern maps directly to
paged_attention V2's cross-partition reduce. Updated muh_kernel_map.py
with the structural mapping and the V2 dispatch bug (use_v1=True
hardcoded in paged_attn.py line 99).
Source: cccl_upstream/cub/cub/agent/single_pass_scan_operators.cuh
cccl_upstream/thrust/examples/summary_statistics.cu