linux-kernel - Re: [PATCH] cpufreq: Avoid configuring old governors as default with intel

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Date:   Fri, 23 Oct 2020 11:47:03 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Mel Gorman <mgorman@...e.de>, Ingo Molnar <mingo@...hat.com>,
        kernel-janitors@...r.kernel.org,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        linux-kernel@...r.kernel.org,
        Valentin Schneider <valentin.schneider@....com>,
        Gilles Muller <Gilles.Muller@...ia.fr>,
        srinivas.pandruvada@...ux.intel.com,
        Linux PM <linux-pm@...r.kernel.org>,
        Len Brown <len.brown@...el.com>
Subject: Re: [PATCH] cpufreq: Avoid configuring old governors as default with
 intel_pstate

On 22-10-20, 18:23, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: [PATCH] cpufreq: Avoid configuring old governors as default with intel_pstate
> 
> Commit 33aa46f252c7 ("cpufreq: intel_pstate: Use passive mode by
> default without HWP") was meant to cause intel_pstate without HWP
> to be used in the passive mode with the schedutil governor on top of
> it by default, but it missed the case in which either "ondemand" or
> "conservative" was selected as the default governor in the existing
> kernel config, in which case the previous old governor configuration
> would be used, causing the default legacy governor to be used on top
> of intel_pstate instead of schedutil.
> 
> Address this by preventing "ondemand" and "conservative" from being
> configured as the default cpufreq governor in the case when schedutil
> is the default choice for the default governor setting.
> 
> [Note that the default cpufreq governor can still be set via the
>  kernel command line if need be and that choice is not limited,
>  so if anyone really wants to use one of the legacy governors by
>  default, it can be achieved this way.]
> 
> Fixes: 33aa46f252c7 ("cpufreq: intel_pstate: Use passive mode by default without HWP")
> Cc: 5.8+ <stable@...r.kernel.org> # 5.8+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/cpufreq/Kconfig |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux-pm/drivers/cpufreq/Kconfig
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/Kconfig
> +++ linux-pm/drivers/cpufreq/Kconfig
> @@ -71,6 +71,7 @@ config CPU_FREQ_DEFAULT_GOV_USERSPACE
>  
>  config CPU_FREQ_DEFAULT_GOV_ONDEMAND
>  	bool "ondemand"
> +	depends on !SMP || !X86_INTEL_PSTATE
>  	select CPU_FREQ_GOV_ONDEMAND
>  	select CPU_FREQ_GOV_PERFORMANCE
>  	help
> @@ -83,6 +84,7 @@ config CPU_FREQ_DEFAULT_GOV_ONDEMAND
>  
>  config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
>  	bool "conservative"
> +	depends on !SMP || !X86_INTEL_PSTATE

While reading this first it felt like a SMP platforms related problem
(which I was surprised about), and then I understood what you are
doing.

I wonder if rewriting it this way makes it more readable with same
result eventually.

	depends on !(X86_INTEL_PSTATE && SMP)

-- 
viresh