From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH] cpufreq, intel_pstate, set max_sysfs_pct and min_sysfs_pct on governor switch Date: Wed, 07 Oct 2015 10:50:17 -0400 Message-ID: <56153129.3080905@redhat.com> References: <1444168147-17812-1-git-send-email-prarit@redhat.com> <1755198.JNkaHg87IV@vostro.rjw.lan> <1594304.lVcRDcB3yL@vostro.rjw.lan> <56150D80.8040609@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56150D80.8040609@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Kristen Carlson Accardi , linux-kernel@vger.kernel.org, Viresh Kumar , linux-pm@vger.kernel.org List-Id: linux-pm@vger.kernel.org On 10/07/2015 08:18 AM, Prarit Bhargava wrote: > > > On 10/06/2015 07:06 PM, Rafael J. Wysocki wrote: >> On Wednesday, October 07, 2015 12:43:55 AM Rafael J. Wysocki wrote: >>> On Tuesday, October 06, 2015 05:49:07 PM Prarit Bhargava wrote: > > > >>>> >>>> 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; >> >> On a second thought, isn't that always 100? If so, doesn't it basically discard >> limits.max_policy_pct? > > Wow :) I think you're right and that definitely was an unintended consequence > of this patch. I also see that I can clean up the intel_pstate_set_policy() > code a bit more. I'll submit a 2-part v2. Kristen, There is a question here and I'm going to need your input on the answer. The question is whether or not a user can exceed the max_policy_pct or drop below the min_policy_pct values via sysfs? If "No, a user should not be able to exceed or go below those values", then IMO limits.max_sysfs_pct should default to limits.max_policy_pct, and limits.min_sysfs_pct should default to limits.min_policy_pct. and I will adjust my patch accordingly. P.