linux-kernel - Re: [PATCH V4 0/3] cpufreq: Allow default governor on cmdline and fix locking issues

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Date:   Tue, 30 Jun 2020 20:38:41 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, Arnd Bergmann <arnd@...db.de>,
        Ben Segall <bsegall@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Cc: Android Kernel" <kernel-team@...roid.com>,
        Todd Kjos <tkjos@...gle.com>, adharmap@...eaurora.org,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Quentin Perret <qperret@...gle.com>
Subject: Re: [PATCH V4 0/3] cpufreq: Allow default governor on cmdline and fix
 locking issues

On Mon, Jun 29, 2020 at 10:58 PM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> Hi,
>
> I have picked Quentin's series over my patch, modified both and tested.
>
> V3->V4:
> - Do __module_get() for cpufreq_default_governor() case as well and get
>   rid of an extra variable.
> - Use a single character array, default_governor, instead of two of them.
>
> V2->V3:
> - default_governor is a string now and we don't set it on governor
>   registration or unregistration anymore.
> - Fixed locking issues in cpufreq_init_policy().
>
> --
> Viresh
>
> Original cover letter fro Quentin:
>
> 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)
>
> Quentin Perret (2):
>   cpufreq: Register governors at core_initcall
>   cpufreq: Specify default governor on command line
>
> Viresh Kumar (1):
>   cpufreq: Fix locking issues with governors
>
>  .../admin-guide/kernel-parameters.txt         |  5 ++
>  Documentation/admin-guide/pm/cpufreq.rst      |  6 +-
>  .../platforms/cell/cpufreq_spudemand.c        | 26 +-----
>  drivers/cpufreq/cpufreq.c                     | 87 ++++++++++++-------
>  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, 100 insertions(+), 140 deletions(-)
>
> --

All three patches applied as 5.9 material, thanks!