linux-kernel - RE: [PATCH v2 0/2] cpufreq: Specify the default governor on command line

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Message-ID: <002201d64987$5dc93b90$195bb2b0$@net>
Date:   Tue, 23 Jun 2020 10:54:33 -0700
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Quentin Perret'" <qperret@...gle.com>
Cc:     <arnd@...db.de>, <mpe@...erman.id.au>, <benh@...nel.crashing.org>,
        <paulus@...ba.org>, <mingo@...hat.com>, <peterz@...radead.org>,
        <juri.lelli@...hat.com>, <vincent.guittot@...aro.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <kernel-team@...roid.com>,
        <tkjos@...gle.com>, <adharmap@...eaurora.org>,
        <viresh.kumar@...aro.org>, <rafael@...nel.org>, <rjw@...ysocki.net>
Subject: RE: [PATCH v2 0/2] cpufreq: Specify the default governor on command line

On 2020.06.23 07:22 Quentin Perret wrote:
> 
> This series enables users of prebuilt kernels (e.g. distro kernels) to
> specify their CPUfreq governor of choice using the kernel command line,
> instead of having to wait for the system to fully boot to userspace to
> switch using the sysfs interface. This is helpful for 2 reasons:
>   1. users get to choose the governor that runs during the actual boot;
>   2. it simplifies the userspace boot procedure a bit (one less thing to
>      worry about).
> 
> To enable this, the first patch moves all governor init calls to
> core_initcall, to make sure they are registered by the time the drivers
> probe. This should be relatively low impact as registering a governor
> is a simple procedure (it gets added to a llist), and all governors
> already load at core_initcall anyway when they're set as the default
> in Kconfig. This also allows to clean-up the governors' init/exit code,
> and reduces boilerplate.
> 
> The second patch introduces the new command line parameter, inspired by
> its cpuidle counterpart. More details can be found in the respective
> patch headers.
> 
> Changes in v2:
>  - added Viresh's ack to patch 01
>  - moved the assignment of 'default_governor' in patch 02 to the governor
>    registration path instead of the driver registration (Viresh)
> 
> Thanks,
> Quentin
> 
> Quentin Perret (2):
>   cpufreq: Register governors at core_initcall
>   cpufreq: Specify default governor on command line
> 
>  .../admin-guide/kernel-parameters.txt         |  5 ++++
>  Documentation/admin-guide/pm/cpufreq.rst      |  6 ++---
>  .../platforms/cell/cpufreq_spudemand.c        | 26 ++-----------------
>  drivers/cpufreq/cpufreq.c                     | 23 ++++++++++++----
>  drivers/cpufreq/cpufreq_conservative.c        | 22 ++++------------
>  drivers/cpufreq/cpufreq_ondemand.c            | 24 +++++------------
>  drivers/cpufreq/cpufreq_performance.c         | 14 ++--------
>  drivers/cpufreq/cpufreq_powersave.c           | 18 +++----------
>  drivers/cpufreq/cpufreq_userspace.c           | 18 +++----------
>  include/linux/cpufreq.h                       | 14 ++++++++++
>  kernel/sched/cpufreq_schedutil.c              |  6 +----
>  11 files changed, 62 insertions(+), 114 deletions(-)
> 
> --
> 2.27.0.111.gc72c7da667-goog

Hi Quentin,

Because I am lazy and sometimes do not want to recompile
the distro source, I have a need/desire for this.

Tested these two grub command lines:

GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 consoleblank=300 intel_pstate=disable cpufreq.default_governor=schedutil cpuidle_sysfs_switch cpuidle.governor=teo"

And

#GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 consoleblank=450 intel_pstate=passive cpufreq.default_governor=schedutil cpuidle_sysfs_switch cpuidle.governor=teo"

And all worked as expected. I use Ubuntu as my distro, and also had to disable a startup script that switches to "ondemand", or similar, after 1 minute.

As a side note (separate subject, but is one reason I tried it):
My i5-9600K based computer seems to hit a power limit during boot approximately 3 seconds after kernel selection on grub.
This had no effect on that issue (even when selecting powersave governor).

... Doug