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Kernel Developers Begin Work On CPPC Processor Performance Controls

Linux Kernel

Published on 15 August 2014 03:52 AM EDT
Written by Michael Larabel in Linux Kernel
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Ashwin Chaugule of Linaro has announced his experimental kernel implementation of Collaborative Processor Performance Controls (CPPC) that is part of the ACPI 5.1 specification.

An increasing amount of x86 and ARM64 hardware is expected in the marketplace soon that supports CPPC, which is a new interface for CPU performance control between the OS and platform, while right now it's just exposed by a limited number of systems. Here's more from Ashwin's description:
CPPC is the new interface for CPU performance control between the OS and the platform defined in ACPI 5.0+. The interface is built on an abstract representation of CPU performance rather than raw frequency. Basic operation consists of:

* Platform enumerates supported performance range to OS

* OS requests desired performance level over some time window along with min and max instantaneous limits

* Platform is free to optimize power/performance within bounds provided by OS

* Platform provides telemetry back to OS on delivered performance

The Collaborative Processor Performance Control work published is largely just a starting point and to initiate discussion about implementing this CPU performance-controlling feature. Those interested in learning much more can read this lengthy email post.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
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