linux-kernel - Re: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency invariance

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Date:   Tue, 29 Jun 2021 10:25:03 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Qian Cai <quic_qiancai@...cinc.com>
Cc:     Ionela Voinescu <ionela.voinescu@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Will Deacon <will@...nel.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency
 invariance

On 26-06-21, 09:41, Qian Cai wrote:
> Another date point is that set ACPI_CPPC_CPUFREQ_FIE=n fixed the issue that any CPU could run below the lowest freq.
> 
> schedutil:
> # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
>      80 1000000
>      78 1400000
>       1 2010000
>       1 2800000
> 
> userspace:
> # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
>     158 1000000
>       2 2000000

ACPI_CPPC_CPUFREQ_FIE can play a role with schedutil, but not with
userspace governor. Userspace doesn't use the values being updated by
ACPI_CPPC_CPUFREQ_FIE. So I think the CPUs may not have been idle,
just for some reason.

Also, now that you are able run on latest kernel (linux-next), it
would be better if we can talk in terms of that only going forward.
5.4 adds more to the already unstable results :)

-- 
viresh