linux-kernel - [PATCH v2] cpufreq: Avoid configuring old governors as default with intel

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Date:   Fri, 23 Oct 2020 17:15:56 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Peter Zijlstra <peterz@...radead.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Julia Lawall <julia.lawall@...ia.fr>
Cc:     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: [PATCH v2] cpufreq: Avoid configuring old governors as default with intel_pstate

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Commit 33aa46f252c7 ("cpufreq: intel_pstate: Use passive mode by
default without HWP") was meant to cause intel_pstate to be used
in the passive mode with the schedutil governor on top of it, 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")
Reported-by: Julia Lawall <julia.lawall@...ia.fr>
Cc: 5.8+ <stable@...r.kernel.org> # 5.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

The v2 addresses a review comment from Viresh regarding of the expression format
and adds a missing Reported-by for Julia.

---
 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 !(X86_INTEL_PSTATE && SMP)
 	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 !(X86_INTEL_PSTATE && SMP)
 	select CPU_FREQ_GOV_CONSERVATIVE
 	select CPU_FREQ_GOV_PERFORMANCE
 	help