You can't always get what you want: P-state selection on Intel CPUs


One Line Summary

An overview of how Performance States work on Intel platforms


This will be an overview of how Performance States (P-states) work on Intel platforms. We will start with how the platform handles p-states. We will then discuss the OS p-state selection algorithm in intel_pstate. Finally, we will talk about hardware controlled p-states (HWP). Knowing how p-state selection actually happens should help us understand how energy aware scheduling in the OS may or may not benefit Intel platforms.


  • Kristen-2014-web-2

    Kristen Accardi

    Intel Corp.


    Kristen is a Linux kernel engineer working on power management for Intel’s Open Source Technology Center and is the maintainer of the intel_pstate driver. Kristen has been contributing to the Linux kernel for over 15 years in various different subsystems including PCI, SATA, and ACPI.