Intel P-State Driver Shifting To "Schedutil" Governor Default With Linux 5.7
On top of all the other changes in Linux 5.7 so far, a secondary set of power management updates were sent in today for this next version of the kernel and includes now using the Schedutil governor by default for Intel P-State and Arm big.LITTLE systems.
Intel's P-State CPU frequency scaling driver has from the start defaulted to the "powersave" governor on most Linux distributions out there (and "performance" on a subset of other distributions as the default, which had been the upstream kernel default Kconfig value). But with time Schedutil has come together as a capable CPU frequency scaling governor that makes use of the kernel's scheduler utilization date to make more accurate decisions about ramping up or down clock frequencies. Schedutil has been looked at by developers on replacing the existing governors as it matures enough.
Last month I wrote that Intel was looking to migrate to P-State Schedutil following patches being published that did so. Following the newly introduced frequency invariance support, the P-State Schedutil configuration should now be at least as good as the existing governors if not better. From the kernel configuration the default governor can still be set.
Besides Intel P-State now using Schedutil as its default governor, the Arm CPUfreq code is also now using schedutil on big.LITTLE systems.
These changes were sent in as part of this pull request. I'll have up some fresh Schedutil benchmarks shortly on Phoronix.
Along similar lines and for those otherwise that would ask in the forums, there is nothing new to report on the AMD CPPC CPUfreq driver for modern Zen systems. I did hear though that AMD will still be pursuing that Linux CPPC support as resources/time allow.
Intel's P-State CPU frequency scaling driver has from the start defaulted to the "powersave" governor on most Linux distributions out there (and "performance" on a subset of other distributions as the default, which had been the upstream kernel default Kconfig value). But with time Schedutil has come together as a capable CPU frequency scaling governor that makes use of the kernel's scheduler utilization date to make more accurate decisions about ramping up or down clock frequencies. Schedutil has been looked at by developers on replacing the existing governors as it matures enough.
Last month I wrote that Intel was looking to migrate to P-State Schedutil following patches being published that did so. Following the newly introduced frequency invariance support, the P-State Schedutil configuration should now be at least as good as the existing governors if not better. From the kernel configuration the default governor can still be set.
Besides Intel P-State now using Schedutil as its default governor, the Arm CPUfreq code is also now using schedutil on big.LITTLE systems.
These changes were sent in as part of this pull request. I'll have up some fresh Schedutil benchmarks shortly on Phoronix.
Along similar lines and for those otherwise that would ask in the forums, there is nothing new to report on the AMD CPPC CPUfreq driver for modern Zen systems. I did hear though that AMD will still be pursuing that Linux CPPC support as resources/time allow.
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