Segment 30

This sub-session finalized the Phase 12 split GPU proving API for the cuzk SNARK proving engine by fixing compilation errors, resolving a use-after-free bug in C++ CUDA code, and achieving a 2.4% throughput improvement (37.1s/proof). Subsequent investigation of OOM errors at higher parallelism led to building a global buffer tracker, which revealed that synthesized partitions were piling up due to premature semaphore release. After iterating through several mitigation strategies—including holding the semaphore until GPU delivery and increasing channel capacity—the optimal balance was found by expanding the GPU channel from 1 to partition_workers, eliminating OOM while preserving throughput.

Fix Phase 12 compilation errors in engine.rs and FFIFix use-after-free bug in groth16_cuda.cuImplement early deallocation of NTT evaluation vectorsBuild global buffer tracker with atomic countersDiagnose memory buildup from partition semaphore releaseOptimize synthesis/GPU channel capacity for memory/throughputBenchmark Phase 12 performance (37.1s/proof)

Phase 12's Split GPU Proving API: From Compilation to Memory Backpressure 4489 words

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