From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093AbbJFWP0 (ORCPT ); Tue, 6 Oct 2015 18:15:26 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:47451 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752567AbbJFWPY (ORCPT ); Tue, 6 Oct 2015 18:15:24 -0400 From: "Rafael J. Wysocki" To: Prarit Bhargava , Kristen Carlson Accardi Cc: linux-kernel@vger.kernel.org, Viresh Kumar , linux-pm@vger.kernel.org Subject: Re: [PATCH] cpufreq, intel_pstate, set max_sysfs_pct and min_sysfs_pct on governor switch Date: Wed, 07 Oct 2015 00:43:55 +0200 Message-ID: <1755198.JNkaHg87IV@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.1.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1444168147-17812-1-git-send-email-prarit@redhat.com> References: <1444168147-17812-1-git-send-email-prarit@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, October 06, 2015 05:49:07 PM Prarit Bhargava wrote: > Intel CPUs will not enter higher p-states when after switching from the > performance governor to the powersave governor, until > /sys/devices/system/cpu/intel_pstate/min_perf_pct is set to a low value. > This differs from previous behaviour in which a switch to the powersave > governor would result in a low default value for min_perf_pct. > > The behavior of the powersave governor changed after commit a04759924e25 > ("[cpufreq] intel_pstate: honor user space min_perf_pct override on > resume"). The commit introduced tracking of performance percentage > changes via sysfs in order to restore userspace changes during > suspend/resume. The problem occurs because the global values of the newly > introduced max_sysfs_pct and min_sysfs_pct are not reset on a governor > change and this causes the new governor to inherit the previous governor's > settings. > > This patch sets max_sysfs_pct to 100 and min_sysfs_pct to 0 on a governor > change which fixes the problem with governor switching. These changes > also make the initial calculations for max_perf_pct and min_perf_pct > slightly simpler. > > Before patch: > [root@intel-skylake-y-01 power]# cpupower frequency-set -g performance > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/min_perf_pct > 100 > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct > 100 > [root@intel-skylake-y-01 power]# cpupower frequency-set -g powersave > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/min_perf_pct > 100 > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct > 100 > > After patch: > [root@intel-skylake-y-01 power]# cpupower frequency-set -g performance > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/min_perf_pct > 100 > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct > 100 > [root@intel-skylake-y-01 power]# cpupower frequency-set -g powersave > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/min_perf_pct > 14 > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct > 100 > > Also note that I have tested suspend/resume (using CONFIG_PM_DEBUG): > [root@intel-skylake-y-01 power]# echo 50 > /sys/devices/system/cpu/intel_pstate/min_perf_pct > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/*_perf_pct > 100 > 50 > [root@intel-skylake-y-01 power]# echo devices > /sys/power/pm_test > [root@intel-skylake-y-01 power]# echo platform > /sys/power/disk > [root@intel-skylake-y-01 power]# echo disk > /sys/power/state > [root@intel-skylake-y-01 power]# cat /sys/devices/system/cpu/intel_pstate/*_perf_pct > 100 > 50 > > Fixes: a04759924e25 ("[cpufreq] intel_pstate: honor user space min_perf_pct override on resume") > Cc: Kristen Carlson Accardi > Cc: "Rafael J. Wysocki" > Cc: Viresh Kumar > Cc: linux-pm@vger.kernel.org > Signed-off-by: Prarit Bhargava > --- > drivers/cpufreq/intel_pstate.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index 3af9dd7..bb24458 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -986,6 +986,9 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) > if (!policy->cpuinfo.max_freq) > return -ENODEV; > > + limits.min_sysfs_pct = 0; > + limits.max_sysfs_pct = 100; > + > if (policy->policy == CPUFREQ_POLICY_PERFORMANCE && > policy->max >= policy->cpuinfo.max_freq) { > limits.min_policy_pct = 100; > @@ -1004,9 +1007,9 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) > limits.max_policy_pct = clamp_t(int, limits.max_policy_pct, 0 , 100); > > /* Normalize user input to [min_policy_pct, max_policy_pct] */ > - limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct); > + limits.min_perf_pct = limits.min_policy_pct; > limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct); > - limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct); > + limits.max_perf_pct = limits.max_sysfs_pct; > limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct); > > /* Make sure min_perf_pct <= max_perf_pct */ > Makes sense to me. Kristen?