linux-kernel - Re: [PATCH v2 1/3] ACPI: processor: perflib: Use the "no limit" frequency QoS

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Date:   Mon, 30 Jan 2023 15:58:47 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Pratyush Yadav <ptyadav@...zon.de>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v2 1/3] ACPI: processor: perflib: Use the "no limit"
 frequency QoS

On Mon, Jan 30, 2023 at 3:18 PM Pratyush Yadav <ptyadav@...zon.de> wrote:
>
> Hi Rafael,
>
> On Thu, Dec 29 2022, Rafael J. Wysocki wrote:
>
> > On Thu, Dec 29, 2022 at 1:58 PM Pratyush Yadav <ptyadav@...zon.de> wrote:
> >>
> >> Hi Rafael,
> >>
> >> On Wed, Dec 28 2022, Rafael J. Wysocki wrote:
> >> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >> >
> >> > When _PPC returns 0, it means that the CPU frequency is not limited by
> >> > the platform firmware, so make acpi_processor_get_platform_limit()
> >> > update the frequency QoS request used by it to "no limit" in that case.
> >> >
> >> > This addresses a problem with limiting CPU frequency artificially on
> >> > some systems after CPU offline/online to the frequency that corresponds
> >> > to the first entry in the _PSS return package.
> >> >
> >> > Reported-by: Pratyush Yadav <ptyadav@...zon.de>
> >> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >> > ---
> [...]
> >>
> >> One small thing I noticed: in acpi_processor_ppc_init() "no limit" value
> >> is set to INT_MAX and here it is set to FREQ_QOS_MAX_DEFAULT_VALUE. Both
> >> should evaluate to the same value but I think it would be nice if the
> >> same thing is used in both places. Perhaps you can fix that up when
> >> applying?
> >
> > Yes, I'll do that.
>
> Following up on this series. I do not see it queued anywhere in the
> linux-pm [0] tree. I would like to have this in the v6.3 merge window if
> possible.
>
> [0] https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/

It's already in the mainline:

e8a0e30b742f cpufreq: intel_pstate: Drop ACPI _PSS states table patching
99387b016022 ACPI: processor: perflib: Avoid updating frequency QoS
unnecessarily
c02d5feb6e2f ACPI: processor: perflib: Use the "no limit" frequency QoS