linux-kernel - Re: [PATCH 1/1, v6] cgroup/freezer: add per freezer duty ratio control

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Message-ID: <4D535627.9090606@linux.intel.com>
Date:	Wed, 09 Feb 2011 19:06:15 -0800
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Matt Helsley <matthltc@...ibm.com>
CC:	jacob.jun.pan@...ux.intel.com, LKML <linux-kernel@...r.kernel.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	container cgroup <containers@...ts.linux-foundation.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Paul Menage <menage@...gle.com>, akpm@...ux-foundation.org,
	rdunlap@...otime.net, Cedric Le Goater <clg@...t.ibm.com>,
	Wysocki Rafael Wysocki <rjw@...k.pl>
Subject: Re: [PATCH 1/1, v6] cgroup/freezer: add per freezer duty ratio control

On 2/9/2011 7:04 PM, Matt Helsley wrote:
> On Tue, Feb 08, 2011 at 05:05:41PM -0800, jacob.jun.pan@...ux.intel.com wrote:
>> From: Jacob Pan<jacob.jun.pan@...ux.intel.com>
>>
>> Freezer subsystem is used to manage batch jobs which can start
>> stop at the same time. However, sometime it is desirable to let
>> the kernel manage the freezer state automatically with a given
>> duty ratio.
>> For example, if we want to reduce the time that backgroup apps
>> are allowed to run we can put them into a freezer subsystem and
>> set the kernel to turn them THAWED/FROZEN at given duty ratio.
>>
>> This patch introduces two file nodes under cgroup
>> freezer.duty_ratio_pct and freezer.period_sec
>>
>> Usage example: set period to be 5 seconds and frozen duty ratio 90%
>> [root@...alhost aoa]# echo 90>  freezer.duty_ratio_pct
>> [root@...alhost aoa]# echo 5000>  freezer.period_ms
> I kept wondering how this was useful when we've got the "cpu" subsystem
> because for some reason "duty cycle" made me think this was a scheduling
> policy knob. In fact, I'm pretty sure it is -- it just happens to
> sometimes reduce power consumption.
>
> Have you tried using the cpu cgroup subsystem's share to see if it can
> have a similar effect?

does the cpu cgroup system work on a 20 to 30 second time window?
the objective is to have the CPU idle, without wakeups, for that long...
(to save power)


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