Segment 26

In this sub-session, the assistant implemented Phase 9 of the cuzk proving engine, focusing on PCIe transfer optimization. Two changes were made: pre-staging a/b/c polynomial uploads outside the GPU mutex using cudaHostRegister and async copy streams (Change 1), and deferred batch sync in Pippenger MSM with double-buffered host result buffers (Change 2). Initial OOM failures were fixed by serializing allocation inside the mutex and adding a memory-aware allocator. Single-worker benchmarks showed dramatic GPU kernel improvements (NTT+MSM -71.6%, tail MSM -34.4%, overall GPU time -50-61%) and throughput improved from 37.4s to 32.1s/proof (+14.2%). Full production benchmark with dual-worker configuration achieved 41.0s/proof, revealing that PCIe bandwidth contention and CPU-side processing are now the limiting factors. The assistant then pivoted to analyzing detailed timing logs to identify the next bottlenecks.

Phase 9 PCIe Transfer Optimization: From 14.2% Breakthrough to the 41-Second Paradox 4174 words

Chunks

• Phase 9 PCIe Transfer Optimization: A Deep Dive into GPU Memory Management, CUDA Pool Asymmetry, and the 14.2% Breakthrough
  2966 words
• The 41-Second Paradox: How Phase 9's Dual-Worker Benchmark Revealed the Next Bottleneck
  2338 words