Linus Torvalds uses Claude Code to write experimental Linux kernel patches

Centre · 2Linux creator Linus Torvalds has used Anthropic's AI coding tool, Claude Code, to develop an eight-patch series for the Linux kernel, according to ZDNET and Computerworld. 1 2 Centre · 2In his Git submission, Torvalds wrote that the code, the test programs, the review behind the list of changes and the first draft of the text were done with an LLM coding assistant (Claude Code) under his direction. 1 2 Centre · 1The series is published on the branch noref-filemap-read-with-llm in Torvalds's repository and aims to remove a bottleneck when multiple threads make small reads from the same file. 1

Centre · 1ZDNET explains that the threads repeatedly take and release references to the folio backing cached data in the page cache, and those reference-count updates require atomic writes to a shared cache line that forces processor cores to compete. It says the problem has been known since 2024 and earlier fix attempts came to nothing. 1 Centre · 1The patches defer reuse of memory removed from the page cache until a read-copy-update (RCU) grace period has elapsed, letting a reader copy data directly into a user buffer without taking a folio reference. 1 Centre · 1On a four-core, eight-thread Intel Core i7-8565U laptop, eight-thread throughput reportedly rose from about 9.9–10.4 million reads per second to 30–33 million, and kernel cycles per read fell from roughly 2,950 to 725; single-thread reads improved from about 452–454 to 408–409 cycles. Torvalds wrote that a machine with more CPUs or more than one socket should gain more, but nothing bigger has been measured. 1

Centre · 1ZDNET cautions that this is not a threefold speed-up of Linux overall but a result from one small-read workload on Torvalds's own laptop, which he had with him in Prague at Linux Plumbers. 1 Centre · 1There are open problems: delaying memory reuse leaves pages unavailable during the grace period, which Torvalds called "the part of this series that is least solved", and reads targeting a not-yet-mapped user page incur an extra failed exception before falling back to the existing path. 1 Centre · 2As of 13 October the branch was not in mainline Linux 7.3-rc6, and both outlets describe the changes as experimental; whether and when they will be merged is undecided. 1 2

Centre · 2Both outlets place the move within Torvalds's gradual shift from scepticism about AI. ZDNET notes he spoke of AI as a helpful tool in December 2023, called himself a huge believer by late 2025, and in January 2026 began using AI-assisted coding on a Python audio visualizer hobby project. 1 2 Centre · 2At Open Source Summit Europe in Prague, in a conversation with Dirk Hohndel, Torvalds said he used to think AI was not very good but now really likes using it, and that it makes programming much more enjoyable. He also cautioned that one needs to be very careful using AI when doing something real and important. 1 2