Linux creator and longtime lead maintainer Linus Torvalds turned to Anthropic’s Claude Code to tackle a kernel performance problem that developers have struggled with for more than two years. On Tuesday, he submitted a 10-patch series that delivered a 23-fold throughput improvement in a synthetic benchmark running on his Ryzen Threadripper.

Torvalds had spent 18 months running a broken version of his own fix for the page-cache reference-counting bottleneck, while other developers had encountered problems with their approaches. The new patches eliminate folio reference-count operations from a common buffered-read path, although Torvalds warned that the benchmark gains would be considerably smaller in real-world workloads.

Reviewers have since identified a race condition and raised concerns about memory reclamation. Torvalds has handed further development to Kiryl Shutsemau, a Linux kernel developer who previously worked on the same bottleneck.

Torvalds had spent 18 months running a broken version of his own fix for the page-cache reference-counting bottleneck, while other developers had encountered problems with their approaches.

On Torvalds’ Core i7-8565U laptop, folio reference-count contention accounted for 99.92% of cross-core load HITMs in eight-thread tests, according to Hardware Busters.

The bottleneck was flagged in 2024 by Matthew Wilcox, an Oracle engineer and longtime Linux kernel memory-management developer, after it surfaced in a customer workload.

On Sunday, Phoronix’s Michael Larabel spotted an experimental branch named noref-filemap-read-with-llm in Torvalds’ tree, which rarely contains anything outside the main development branch.

3-rc6, came with a clear account of what Claude Code did. Torvalds said the assistant wrote the implementation, tests, and initial documentation, and reviewed the code under his direction.

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