linux-kernel - Re: 4.8.1 regression with cpufreq governors

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Message-ID: <2549240.nvakNXlyKF@vostro.rjw.lan>
Date:   Tue, 18 Oct 2016 23:10:19 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Tim Walberg <twalberg@...cast.net>
Cc:     linux-kernel@...r.kernel.org,
        Linux PM list <linux-pm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: 4.8.1 regression with cpufreq governors

On Monday, October 17, 2016 07:46:06 PM Tim Walberg wrote:
> May or may not be related to similar reports, but here's what I've just observed
> on my system. Built a stock kernel from tags/v4.8.1, relevant cpufreq bits:
> 
> CONFIG_ACPI_CPU_FREQ_PSS=y
> CONFIG_CPU_FREQ=y
> CONFIG_CPU_FREQ_GOV_ATTR_SET=y
> CONFIG_CPU_FREQ_GOV_COMMON=y
> CONFIG_CPU_FREQ_STAT=y
> CONFIG_CPU_FREQ_STAT_DETAILS=y
> # CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is not set
> # CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE is not set
> # CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE is not set
> # CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND is not set
> CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE=y
> # CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL is not set
> CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
> CONFIG_CPU_FREQ_GOV_POWERSAVE=m
> CONFIG_CPU_FREQ_GOV_USERSPACE=m
> CONFIG_CPU_FREQ_GOV_ONDEMAND=m
> CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
> CONFIG_CPU_FREQ_GOV_SCHEDUTIL=m
> # CONFIG_X86_PCC_CPUFREQ is not set
> CONFIG_X86_ACPI_CPUFREQ=m
> CONFIG_X86_ACPI_CPUFREQ_CPB=y
> 
> 
> Conservative is set as default governer, yet when boot completes, all CPUs are
> pegged at the highest frequency. Changing governor to powersave knocks them all
> down to the lowest available frequency. Putting them back on conservative (or
> ondemand) results in no change in frequency, despite generating load. Switching
> to performance of course kicks them back up to high frequency. Basically, the
> governors don't seem to be ... governing.

The "convervative" governor issue seems to be the one fixed recently
(http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=pm-cpufreq&id=abb6627910a1e783c8e034b35b7c80e5e7f98f41).

I'm not sure why "ondemand" behaves incorrectly for you though.

Thanks,
Rafael