Chunk 23.0

This chunk describes the successful implementation and initial benchmarking of Phase 7 of the cuzk SNARK proving engine, a fundamental architectural shift that treats each of the 10 PoRep partitions as an independent work unit flowing through the engine pipeline. Following the detailed specification in `c2-optimization-proposal-7.md`, the agent systematically executed the six-step plan: extending data structures (`SynthesizedJob`, `JobTracker`, `PartitionedJobState`), refactoring the dispatch logic in `process_batch()` to use a semaphore-gated pool of 20 `spawn_blocking` workers, adding partition-aware routing to the GPU worker loop, and integrating error handling and memory management (`malloc_trim`). The implementation compiled cleanly and was committed as `f5bfb669` on the `feat/cuzk` branch. Initial test runs confirmed the core mechanism works correctly: each partition is synthesized individually, proved with `num_circuits=1` (achieving the predicted ~0.4s `b_g2_msm`), and routed to a `ProofAssembler` which delivers the final 1920-byte proof. Single-proof latency was 72.8s (including cold-start synthesis), and multi-proof throughput tests with 5 proofs showed significant improvement, achieving ~45–50s/proof wall-clock time with concurrency 2–3. Timeline analysis confirmed the pipeline is flowing, with inter-partition GPU gaps shrinking to tens of milliseconds after the initial synthesis burst. The user observed that GPU utilization remains "pretty jumpy" despite these improvements, pointing to per-job overhead and pipeline smoothness as the next optimization frontier. The agent was actively investigating the exact GPU idle gaps between partitions when the chunk concluded, demonstrating the iterative, measurement-driven engineering approach central to the project. The immediate next steps involve deeper profiling of GPU worker overhead and potentially implementing a dual-GPU-worker strategy to keep the CUDA hardware continuously saturated.

From Architecture to Diagnosis: The Phase 7 Journey Through Implementation, Benchmarking, and the Discovery of Phase 8 1590 words

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