Auto-research with codex: How I achieved a 232x Faster Kernel(sankalp.bearblog.dev)
445 points by tosh 6 days ago | 92 comments
tl;dr: A participant in GPU Mode's auto-research contest achieved a 232x speedup (from ~419ms to 1.8ms) over baseline on batched Householder QR factorization, placing 12th of 183 by running Codex agents in tight feedback loops with the popcorn CLI over 1500+ submissions. Key techniques included blocked Householder with WY-updates, fused V/T layouts, CUDA graph replay, and shape-specialized kernels. The author emphasizes that escaping local maxima required a "beam of candidates" strategy, human-in-the-loop steering, and stronger advisor models—arguing that idea diversity and research taste, not raw model intelligence, are now the bottleneck in auto-research.
HN Discussion:
  • ~LLM-optimized solutions overfit to specific inputs and break on out-of-distribution shapes, unlike expert-crafted ones
  • Sharing similar personal experience using agentic loops for performance optimization on other codebases
  • LLMs excel at optimization broadly but fall short of peak human-crafted performance
  • Questioning the technical soundness of substituting Cholesky for Householder given stability tradeoffs
  • Solo engineer achieving this weakens the competitive moat of major AI labs