The new Intel Performance Limit Reasons (PLR) feature provides insight into why a CPU may be throttling or performing at a lower limit. This information is now available on Linux, in addition to existing Windows utilities. PLR can indicate whether performance is being limited at the chip level or for individual CPU cores within a chip. With recent Linux kernel patches, Intel PLR hardware performance event reports are now accessible, transmitted through DebugFS for user space consumption. This allows administrators and other applications to understand why their CPU performance may be restricted.
The Linux patches for Intel performance limiting reasons transmit information over "/sys/kernel/debug/tpmi-/plr/domain/status." However, access to "/sys/kernel/debug/" is usually restricted to software with root or administrator privileges. A new Kconfig option called "INTEL_PLR_TPMI" controls the Intel PLR driver, and it is expected to be included in Linux v6.11. Those interested in Intel PLR functionality can access the new driver patches on the core mailing list.
In summary, the new Intel PLR feature enables users to understand why a CPU may be operating at a lower performance limit. The information is now available on Linux through recent kernel patches, transmitted through DebugFS for user space consumption. Users can access this information to troubleshoot performance issues and optimize CPU performance. The inclusion of the Intel PLR driver in the upcoming Linux v6.11 release will provide a standardized method for accessing this important data. Users with root or administrator privileges can utilize the new feature to better understand and address CPU performance limitations.
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