A Fix Is Pending For That Linux 5.15 Performance Regression

Written by Michael Larabel in Software on 23 September 2021. Page 1 of 4. 5 Comments

Last week was the article on noticing various workloads performing slower on the Linux 5.15 development kernel. There is now a patch pending that in testing so far does indeed correct the performance drop on this forthcoming kernel.

As outlined in that prior article, the Linux 5.15 performance regression was tracked down to memory accounting "memcg" changes that landed during the Linux 5.15 merge window.

Google's Shakeel Butt who was responsible for those Memcg changes has prepared a patch to address the issue: [PATCH] memcg: flush lruvec stats in the refault.

With changing around less than one dozen lines of code, the regression should now be resolved. I've been testing out this and former patch the past few days and indeed the Linux 5.15 regression is addressed.

Here is a look at the difference with this patch applied now to Linux 5.15.

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