Linux 5.15 Lands Memcg Performance Regression Fix

As a follow-up to A Fix Is Pending For That Linux 5.15 Performance Regression, Linus Torvalds decided to pull the fix directly into Linux 5.15 Git today for addressing this real-world, measurable performance regression.

Linus commented on the proposed memcg change today, "Ok, I've applied this just to close the issue. If somebody comes up with more data and the delayed flushing or something is problematic, we'll revisit, but this looks all sane to me and fixes the regression."

So for Linux 5.15 now in Git, the performance should be back into good shape and comparable to Linux 5.14 for workloads like code compilation and various other workloads I've personally seen regressed from RawTherapee imaging to JPEG-XL image encode/decode and various other application workloads. See this morning's article or last week's regression report for details on the impact.



From other tests I have ongoing, Linux 5.15 overall should be in good shape and haven't seen any other glaring regressions. The Linux 5.15 performance is now stable and this kernel has many new features. Linux 5.15 should debut as stable in early November.