Linux 6.1 Picks Up Some Improvements For Pressure Stall Information (PSI)

Written by Michael Larabel in Linux Kernel on 15 October 2022 at 06:00 AM EDT. 2 Comments
LINUX KERNEL --
Among the pull requests coming in late in the merge window for the Linux 6.1 cycle is the "sched/psi" updates for the code improvements around Pressure Stall Information.

Linux's Pressure Stall Information (PSI) is used for quantifying CPU, memory, and I/O contention under load when the system is starved for resources. Linux's PSI helps to analyze resource issues with this aggregated real-time information and particularly comes into play around out-of-memory kills.

With Linux 6.1 there is now support for turning the Pressure Stall Information on or off at a per-cgroup level. This per-cgroup control around PSI information is useful since this accounting can add some extra overhead to workloads and thus can be selectively disabled where desired. This interface is exposed via cgroup.pressure via sysfs for enabling/disabling cgroup PSI accounting.

The other notable change with the PSI updates for Linux 6.1 are some performance optimizations. Developers have found a 4~9% speed-up under a scheduler micro-benchmark with the latest PSI code changes.

The list of sched/psi patches for the Linux 6.1 merge window can be found via this now honored pull request.
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Michael Larabel is the principal author of Phoronix.com 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 OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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