Re: [PATCH] cpufreq: Avoid configuring old governors as default with intel_pstate

From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Julia Lawall <julia.lawall@inria.fr>,
	Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@redhat.com>,
	kernel-janitors@vger.kernel.org,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	linux-kernel@vger.kernel.org,
	Valentin Schneider <valentin.schneider@arm.com>,
	Gilles Muller <Gilles.Muller@inria.fr>,
	srinivas.pandruvada@linux.intel.com,
	Linux PM <linux-pm@vger.kernel.org>,
	Len Brown <len.brown@intel.com>
Subject: Re: [PATCH] cpufreq: Avoid configuring old governors as default with intel_pstate
Date: Fri, 23 Oct 2020 11:47:03 +0530	[thread overview]
Message-ID: <20201023061703.jjpmoeq7wzwqtsid@vireshk-i7> (raw)
In-Reply-To: <8312288.dAKoTdFk2S@kreacher>

On 22-10-20, 18:23, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.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@vger.kernel.org> # 5.8+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.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