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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: hannes@cmpxchg.org, Christoph Lameter <cl@linux.com>,
	Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	vinmenon@codeaurora.org, shashim@codeaurora.org,
	Michal Hocko <mhocko@suse.cz>,
	mgorman@suse.de, dave@stgolabs.net, koct9i@gmail.com,
	Linux Memory Management List <linux-mm@kvack.org>,
	Suresh Siddha <suresh.b.siddha@intel.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work
Date: Fri, 27 Mar 2015 10:19:54 +0530	[thread overview]
Message-ID: <CAKohpo=nTXutbVVf-7iAwtgya4zUL686XbG69ExQ3Pi=VQRE-A@mail.gmail.com> (raw)
In-Reply-To: <20150326131822.fce6609efdd85b89ceb3f61c@linux-foundation.org>

On 27 March 2015 at 01:48, Andrew Morton <akpm@linux-foundation.org> wrote:
> Shouldn't this be viewed as a shortcoming of the core timer code?

Yeah, it is. Some (not so pretty) solutions were tried earlier to fix that, but
they are rejected for obviously reasons [1].

> vmstat_shepherd() is merely rescheduling itself with
> schedule_delayed_work().  That's a dead bog simple operation and if
> it's producing suboptimal behaviour then we shouldn't be fixing it with
> elaborate workarounds in the caller?

I understand that, and that's why I sent it as an RFC to get the discussion
started. Does anyone else have got another (acceptable) idea to get this
resolved ?

--
viresh

[1] http://lists.linaro.org/pipermail/linaro-kernel/2013-November/008866.html

WARNING: multiple messages have this Message-ID (diff)
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: hannes@cmpxchg.org, Christoph Lameter <cl@linux.com>,
	Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	vinmenon@codeaurora.org, shashim@codeaurora.org,
	Michal Hocko <mhocko@suse.cz>,
	mgorman@suse.de, dave@stgolabs.net, koct9i@gmail.com,
	Linux Memory Management List <linux-mm@kvack.org>,
	Suresh Siddha <suresh.b.siddha@intel.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work
Date: Fri, 27 Mar 2015 10:19:54 +0530	[thread overview]
Message-ID: <CAKohpo=nTXutbVVf-7iAwtgya4zUL686XbG69ExQ3Pi=VQRE-A@mail.gmail.com> (raw)
In-Reply-To: <20150326131822.fce6609efdd85b89ceb3f61c@linux-foundation.org>

On 27 March 2015 at 01:48, Andrew Morton <akpm@linux-foundation.org> wrote:
> Shouldn't this be viewed as a shortcoming of the core timer code?

Yeah, it is. Some (not so pretty) solutions were tried earlier to fix that, but
they are rejected for obviously reasons [1].

> vmstat_shepherd() is merely rescheduling itself with
> schedule_delayed_work().  That's a dead bog simple operation and if
> it's producing suboptimal behaviour then we shouldn't be fixing it with
> elaborate workarounds in the caller?

I understand that, and that's why I sent it as an RFC to get the discussion
started. Does anyone else have got another (acceptable) idea to get this
resolved ?

--
viresh

[1] http://lists.linaro.org/pipermail/linaro-kernel/2013-November/008866.html

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  reply	other threads:[~2015-03-27  4:49 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-26  5:39 [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work Viresh Kumar
2015-03-26  5:39 ` Viresh Kumar
2015-03-26 20:18 ` Andrew Morton
2015-03-26 20:18   ` Andrew Morton
2015-03-27  4:49   ` Viresh Kumar [this message]
2015-03-27  4:49     ` Viresh Kumar
2015-03-27  9:16     ` Peter Zijlstra
2015-03-27  9:16       ` Peter Zijlstra
2015-03-27  9:30       ` Peter Zijlstra
2015-03-27  9:30         ` Peter Zijlstra
2015-03-27 11:11         ` Christoph Lameter
2015-03-27 11:11           ` Christoph Lameter
2015-03-27 12:02           ` Peter Zijlstra
2015-03-27 12:02             ` Peter Zijlstra
2015-03-27 19:45             ` Christoph Lameter
2015-03-27 19:45               ` Christoph Lameter
2015-03-28  4:28             ` Viresh Kumar
2015-03-28  4:28               ` Viresh Kumar
2015-03-28 11:41               ` Peter Zijlstra
2015-03-28 11:41                 ` Peter Zijlstra
2015-03-28  4:18         ` Viresh Kumar
2015-03-28  4:18           ` Viresh Kumar
2015-03-28  9:53           ` Peter Zijlstra
2015-03-28  9:53             ` Peter Zijlstra
2015-03-28 11:57             ` viresh kumar
2015-03-28 11:57               ` viresh kumar
2015-03-28 12:04               ` Viresh Kumar
2015-03-28 12:04                 ` Viresh Kumar
2015-03-28 13:44               ` Peter Zijlstra
2015-03-28 13:44                 ` Peter Zijlstra
2015-03-29 10:24                 ` Peter Zijlstra
2015-03-29 10:24                   ` Peter Zijlstra
2015-03-30 12:02                   ` Viresh Kumar
2015-03-30 12:02                     ` Viresh Kumar
2015-03-30 12:47                     ` Peter Zijlstra
2015-03-30 12:47                       ` Peter Zijlstra
2015-03-30 13:14                       ` Viresh Kumar
2015-03-30 13:14                         ` Viresh Kumar
2015-03-30 13:59                         ` Peter Zijlstra
2015-03-30 13:59                           ` Peter Zijlstra
2015-03-30 16:17                           ` Viresh Kumar
2015-03-30 16:17                             ` Viresh Kumar
2015-03-30 16:25                             ` Peter Zijlstra
2015-03-30 16:25                               ` Peter Zijlstra
2015-03-29 12:01                 ` Viresh Kumar
2015-03-29 12:01                   ` Viresh Kumar
2015-03-29 17:24                   ` Peter Zijlstra
2015-03-29 17:24                     ` Peter Zijlstra
2015-03-30 15:08             ` Michal Hocko
2015-03-30 15:08               ` Michal Hocko
2015-03-30 15:14               ` Peter Zijlstra
2015-03-30 15:14                 ` Peter Zijlstra
2015-03-30 15:42               ` Christoph Lameter
2015-03-30 15:42                 ` Christoph Lameter
2015-03-27 14:19 ` Michal Hocko
2015-03-27 14:19   ` Michal Hocko
2015-03-28  4:34   ` Viresh Kumar
2015-03-28  4:34     ` Viresh Kumar

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