Linux 6.4 Scheduler Updates Fixes A Database Performance Regression

Written by Michael Larabel in Linux Kernel on 28 April 2023 at 06:16 AM EDT. 1 Comment
All of the scheduler changes were sent out on Thursday that are ready for the Linux 6.4 kernel.

First up, the Linux 6.4 scheduler material fixes a performance regression that was introduced in Linux 6.3 due to "mm_cid" changes. Going back to March when Linux 6.3 was in development it was observed by Intel that there was a performance regression affecting PostgreSQL with heavy contention compared to Linux 6.2.

The fix involves keeping track of the current allocated mm_cid for each mm/cpu rather than freeing immediately on context switch. After this regression fix went through eight rounds of review, it's ready now for Linux 6.4 so that PostgreSQL is happy and presumably some other workloads as well.

As another scheduler performance change for this new kernel, the sched_move_task operation should also see better performance too when using config auto-group.

Linux 6.4 scheduler changes also include now supporting unprivileged PSI profiling, improving live-patch stalls, and for core-scheduling CPUs to avoid selecting throttled tasks to run.

More details on the Linux 6.4 scheduler updates via this pull request.
Related News
About The Author
Michael Larabel

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

Popular News This Week