linux-kernel - RE: [PATCH 0/4] Allow cpuidle governors to be compiled as modules

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Date:   Thu, 25 Nov 2021 09:16:25 -0800
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Maulik Shah'" <quic_mkshah@...cinc.com>,
        <bjorn.andersson@...aro.org>, <rafael@...nel.org>,
        <daniel.lezcano@...aro.org>
Cc:     <linux-arm-msm@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <ulf.hansson@...aro.org>,
        <quic_lsrao@...cinc.com>, <rnayak@...eaurora.org>,
        "Doug Smythies" <dsmythies@...us.net>
Subject: RE: [PATCH 0/4] Allow cpuidle governors to be compiled as modules

Hi All,

I realize that previous replies render this one useless
but sending anyhow.

On 2021.11.25 00:55 Maulik Shah wrote:

> This series makes changes to allow cpuidle governors
> menu, ladder and teo to compiled as modules when
> building with allmodconfig.

One current issue with governors being available as modules
is that they don't appear on the available governors list unless
they are loaded.

Example with this patch set, all done as modules:

~$ grep . /sys/devices/system/cpu/cpuidle/*
/sys/devices/system/cpu/cpuidle/current_driver:none
/sys/devices/system/cpu/cpuidle/current_governor:none
/sys/devices/system/cpu/cpuidle/current_governor_ro:none

However, and based on my systems power consumption,
some sort of idle must be running.

~$ echo teo | sudo tee /sys/devices/system/cpu/cpuidle/current_governor
teo
tee: /sys/devices/system/cpu/cpuidle/current_governor: Invalid argument

~$ sudo modprobe teo
~$ grep . /sys/devices/system/cpu/cpuidle/*
/sys/devices/system/cpu/cpuidle/available_governors:teo
/sys/devices/system/cpu/cpuidle/current_driver:none
/sys/devices/system/cpu/cpuidle/current_governor:teo
/sys/devices/system/cpu/cpuidle/current_governor_ro:teo

By the way, for the cpufreq stuff, while governors that
are actually available, but are modules, changing to them
without first force loading the module works:

$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:performance schedutil
/sys/devices/system/cpu/cpu10/cpufreq/scaling_available_governors:performance schedutil
...

$ echo ondemand | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
ondemand

$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:ondemand performance schedutil
/sys/devices/system/cpu/cpu10/cpufreq/scaling_available_governors:ondemand performance schedutil

... Doug