Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 16 Nov 2022 13:17:47 +0100 | Subject | Re: [PATCH v1] Revert "cpufreq: schedutil: Move max CPU capacity to sugov_policy" |
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On Wed, Nov 16, 2022 at 12:43 PM Lukasz Luba <lukasz.luba@arm.com> wrote: > > > > On 11/15/22 22:35, Saravana Kannan wrote: > > On Thu, Nov 10, 2022 at 11:57 AM Sam Wu <wusamuel@google.com> wrote: > >> > >> This reverts commit 6d5afdc97ea71958287364a1f1d07e59ef151b11. > >> > >> On a Pixel 6 device, it is observed that this commit increases > >> latency by approximately 50ms, or 20%, in migrating a task > >> that requires full CPU utilization from a LITTLE CPU to Fmax > >> on a big CPU. Reverting this change restores the latency back > >> to its original baseline value. > >> > >> Fixes: 6d5afdc97ea7 ("cpufreq: schedutil: Move max CPU capacity to sugov_policy") > >> Cc: Lukasz Luba <lukasz.luba@arm.com> > >> Cc: Saravana Kannan <saravanak@google.com> > >> Cc: Isaac J. Manjarres <isaacmanjarres@google.com> > >> Signed-off-by: Sam Wu <wusamuel@google.com> > > > > Rafael, can we pick this up please? > > > > Lukasz, no objections to the idea itself, but it's causing regression > > and we'd like to revert and then fix it. > > If you see this in mainline kernel, then I'm fine with reverting it.
OK, I'll wait for the confirmation of this.
> Then I will have to trace why this CPU capacity value can change over > time in mainline kernel (while it shouldn't, because we register the > cpufreq policy and the governor later, after we calculate the capacity > in arch_topology.c). Maybe something has changed in mainline in the > meantime in this CPU capacity setup code, which caused this side effect. > > I know that android-mainline has some different setup code for those > custom vendor governors. I just want to eliminate this bit and be on the > same page.
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