Virtual CPUFreq Driver Coming With Linux 6.13 For Better Power/Performance Within VMs

Written by Michael Larabel in Virtualization on 24 November 2024 at 06:58 AM EST. 4 Comments
VIRTUALIZATION
Earlier this week was the main power management updates for Linux 6.13 that included switching AMD EPYC Turin to using the amd_pstate driver on supported systems. Sent out this weekend was another set of power management updates that also includes a notable addition: the virtual CPUFreq driver.

Included now for Linux 6.13 is the virtual-cpufreq driver as a virtualized CPU frequency scaling driver. The virtual-cpufreq driver is intended for guest virtual machine (VM) kernels for helping to improve the performance and power of workloads operating within VMs.

This Virtual CPUFreq driver developed by Google engineers will send the frequency of vCPUs as a hint to the host and in turn the host can use that hint to schedule the vCPU threads and decode the physical CPU frequency. This driver also allows for updating the guest's frequency scaling factor periodically for allowing accurate per-entity load tracking within the guests.

CPUFREQ_VIRT Kconfig


It will be interesting to see the impact in practice on power/performance for finally having this Virtual CPUFreq driver going mainline. Back when Google engineers first presented the work last year they were talking of dramatic VM performance and power efficiency benefits.

The Virtual CPUFreq driver is the main exciting element of the secondary power management updates for the in-development Linux 6.13 kernel.
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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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