Intel Performance Limit Reasons Coming To Linux 6.11

Set to be merged for the upcoming Linux 6.11 kernel cycle is Intel's "Performance Limit Reasons" reporting for indicating why a processor may be downclocking.

Back in May I wrote about Intel's patches for Performance Limit Reasons on Linux to indicate why a given CPU core or die is seeing limited performance. That code is now ready and queued up for merging with the upcoming Linux 6.11 cycle.

Windows has already made use of the PLR hardware performance event while Linux 6.11 will see support integrated. Via DebugFS, administrators / user-space software will be able to see why individual CPU cores or a die may be performance limited. The new "/sys/kernel/debug/tpmi-*/plr/domain*/status" DebugFS interface will indicate the Performance Limit Reasons such as aroud thermal and power constraints.

The Performance Limit Reasons support for Intel CPUs in Linux 6.11 will land as part of the platform-drivers-x86.git's for-next Git branch. Linux 6.11 stable in turn should be out in September with this new Intel PLR capability and many other changes -- stay tuned to Phoronix for more coverage of the v6.11 kernel development.