Linux 5.15 Lands Memcg Performance Regression Fix

Written by Michael Larabel in Linux Kernel on 24 September 2021 at 12:00 AM EDT. 1 Comment
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.
Linux 5.15 Kernel Patch Tests - AMD Ryzen 9 5950X

Linux 5.15 Kernel Patch Tests - AMD Ryzen 9 5950X

Linux 5.15 Kernel Patch Tests - AMD Ryzen 9 5950X

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.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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