Linus Torvalds' recent kernel tweak eliminates a barrier function, improving multithread performance by 2.6% while addressing speculative‑execution vulnerabilities like Meltdown and Spectre, illustrating the trade‑off between speed and security in modern Linux systems.
Linus Torvalds merged a kernel patch that modifies the 64‑bit copy_from_user() implementation to avoid the slow barrier_nospec() call, achieving a 2.6% performance improvement in the "will it scale" benchmark and will be included in the upcoming Linux 6.12 stable release.
Linus Torvalds merged a small patch into the Linux kernel that streamlines the 64‑bit copy_from_user() routine by skipping the costly barrier_nospec() and applying masked user‑address handling, delivering a 2.6% speedup on Intel’s “will it scale” per‑thread‑ops benchmark and slated for inclusion in the upcoming Linux 6.12 stable release.
The article explains that kernel code must copy user‑space buffers with copy_from_user rather than using memcpy, covering the necessity of copying, the built‑in access checks, page‑fault handling, security implications, and modern hardware safeguards like PAN.
