Messages in this thread | | | From | "Doug Smythies" <> | Subject | RE: [PATCH v3 0/4] cpufreq: intel_pstate: Handle powersave governor correctly in the passive mode with HWP | Date | Tue, 10 Nov 2020 13:37:00 -0800 |
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On 2020.11.10 09:22 Rafael J. Wysocki wrote: > On Monday, November 9, 2020 5:49:49 PM CET Rafael J. Wysocki wrote: >> >> Even after the changes made very recently, the handling of the powersave >> governor is not exactly as expected when intel_pstate operates in the >> "passive" mode with HWP enabled. >> >> Namely, in that case HWP is not limited to the policy min frequency, but it >> can scale the frequency up to the policy max limit and it cannot be constrained >> currently, because there are no provisions for that in the framework. >> >> To address that, patches [1-3/4] add a new governor flag to indicate that this >> governor wants the target frequency to be set to the exact value passed to the >> driver, if possible, and change the powersave and performance governors to have >> that flag set. >> >> The last patch makes intel_pstate take that flag into account when programming >> the HWP Request MSR. > > The v3 simply uses different names for the new governor flags.
Thank you.
I tested v2, with positive results, as reported for v1. I do not have time to re-test v3.
My input is to also default this flag to be set for the userspace and ondemand governors.
userspace: I tested with and without this flag set, and the flag is needed if the user expects the scaling_setspeed to be enforced. Disclaimer: I don't normally actually use the userspace governor.
ondemand: from my tests, the ondemand response more closely mimics acpi-ondemand with the flag set. Power consumption has been better for the limited testing done. However, it is also a function of work/sleep frequency for periodic workflows and a function of INTEL_CPUFREQ_TRANSITION_DELAY_HWP. I am saying that my ability to support the suggestion to default to setting the flag is a little weak.
... Doug
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