From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM list <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Steve Muckle <steve.muckle@linaro.org>
Subject: Re: [PATCH] sched/fair: Invoke cpufreq hooks for CONFIG_SMP unset
Date: Sat, 7 May 2016 08:30:51 +0200 [thread overview]
Message-ID: <20160507063051.GA23722@gmail.com> (raw)
In-Reply-To: <20160507061310.GA15728@worktop.ger.corp.intel.com>
* Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, May 06, 2016 at 02:58:43PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization
> > update callbacks) overlooked the fact that update_load_avg(), where
> > CFS invokes cpufreq utilization update hooks, becomes an empty stub for
> > CONFIG_SMP unset. In consequence, if CONFIG_SMP is not set, cpufreq
> > governors are never invoked from CFS and they do not have a chance to
> > evaluate CPU performace levels and update them often enough. Needless
> > to say, things don't work as expected then.
> >
> > Fix the problem by making the !CONFIG_SMP stub of update_load_avg()
> > invoke cpufreq update hooks too.
> >
> > Fixes: 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks)
> > Reported-by: Steve Muckle <steve.muckle@linaro.org>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Rafael; feel free to push this through the pm tree.
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
I already have it in sched/urgent.
Thanks,
Ingo
next prev parent reply other threads:[~2016-05-07 6:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-06 12:58 [PATCH] sched/fair: Invoke cpufreq hooks for CONFIG_SMP unset Rafael J. Wysocki
2016-05-06 19:08 ` Steve Muckle
2016-05-06 19:36 ` Rafael J. Wysocki
2016-05-07 6:13 ` Peter Zijlstra
2016-05-07 6:30 ` Ingo Molnar [this message]
2016-05-09 8:30 ` Peter Zijlstra
2016-05-09 23:53 ` Steve Muckle
2016-05-09 23:58 ` Rafael J. Wysocki
2016-05-10 8:13 ` Ingo Molnar
2016-05-07 6:37 ` [tip:sched/urgent] sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage tip-bot for Rafael J. Wysocki
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