From: Michal Hocko <mhocko@suse.cz>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, cl@linux.com,
linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org,
vinmenon@codeaurora.org, shashim@codeaurora.org, mgorman@suse.de,
dave@stgolabs.net, koct9i@gmail.com, linux-mm@kvack.org
Subject: Re: [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work
Date: Fri, 27 Mar 2015 15:19:22 +0100 [thread overview]
Message-ID: <20150327141922.GC5481@dhcp22.suse.cz> (raw)
In-Reply-To: <359c926bc85cdf79650e39f2344c2083002545bb.1427347966.git.viresh.kumar@linaro.org>
On Thu 26-03-15 11:09:01, Viresh Kumar wrote:
> A delayed work to schedule vmstat_shepherd() is queued at periodic intervals for
> internal working of vmstat core. This work and its timer end up waking an idle
> cpu sometimes, as this always stays on CPU0.
>
> Because we re-queue the work from its handler, idle_cpu() returns false and so
> the timer (used by delayed work) never migrates to any other CPU.
>
> This may not be the desired behavior always as waking up an idle CPU to queue
> work on few other CPUs isn't good from power-consumption point of view.
Wouldn't something like I was suggesting few months back
(http://article.gmane.org/gmane.linux.kernel.mm/127569) solve this
problem as well? Scheduler should be idle aware, no? I mean it shouldn't
wake up an idle CPU if the task might run on another one.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2015-03-27 14:19 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 5:39 Viresh Kumar
2015-03-26 20:18 ` Andrew Morton
2015-03-27 4:49 ` Viresh Kumar
2015-03-27 9:16 ` Peter Zijlstra
2015-03-27 9:30 ` Peter Zijlstra
2015-03-27 11:11 ` Christoph Lameter
2015-03-27 12:02 ` Peter Zijlstra
2015-03-27 19:45 ` Christoph Lameter
2015-03-28 4:28 ` Viresh Kumar
2015-03-28 11:41 ` Peter Zijlstra
2015-03-28 4:18 ` Viresh Kumar
2015-03-28 9:53 ` Peter Zijlstra
2015-03-28 11:57 ` viresh kumar
2015-03-28 12:04 ` Viresh Kumar
2015-03-28 13:44 ` Peter Zijlstra
2015-03-29 10:24 ` Peter Zijlstra
2015-03-30 12:02 ` Viresh Kumar
2015-03-30 12:47 ` Peter Zijlstra
2015-03-30 13:14 ` Viresh Kumar
2015-03-30 13:59 ` Peter Zijlstra
2015-03-30 16:17 ` Viresh Kumar
2015-03-30 16:25 ` Peter Zijlstra
2015-03-29 12:01 ` Viresh Kumar
2015-03-29 17:24 ` Peter Zijlstra
2015-03-30 15:08 ` Michal Hocko
2015-03-30 15:14 ` Peter Zijlstra
2015-03-30 15:42 ` Christoph Lameter
2015-03-27 14:19 ` Michal Hocko [this message]
2015-03-28 4:34 ` Viresh Kumar
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