linux-kernel - RE: [PATCH] proc: Get/set timer slack through /proc

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Date:	Mon, 4 Jan 2010 09:29:21 -0800
From:	"Smith, GeoffX" <geoffx.smith@...el.com>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] proc: Get/set timer slack through /proc


On Friday, January 01, 2010, Arjan@...radead.org wrote:

>On Thu, 31 Dec 2009 13:01:49 -0800 
>"Smith, GeoffX" <geoffx.smith@...el.com> wrote:
>
>> Subject: Get/set timer_slack_ns through /proc
>>
>> This patch makes the timer_slack_ns parameter accessible through
>> the /proc system.
>>
>> On 9/1/2008, arjan@...ux.intel.com submitted a patch to allow a
>> process to set the timer slack value as part of the range timers
>> feature.  Further, he noted that "Applications and admins can
>> override this [the timer slack value] via the prctl()."
>>
>> We have found this feature useful in attempting to reduce system
>> wakeups caused by timer interrupts.  But we have also found that
>> while applications can set their own timer slack value, there is no
>> provision for setting the timer slack for another process -- prctl()
>> only operates on the current process.
>
>this statement is incorrect btw;
>timerslack is explicitly inherited over exec, so you can have (and we
>do have) a utility similar to the nice program, that launches an
>application with a specific timer slack.

Hmmm, that seems a lot less flexible, but I see how that would work.

Nonetheless, using "nice" as a model is that you would have to modify anything that launches applications, right?  This would mean modifying /etc/init.d and application scripts, which seems beyond the scope of "admin".   Or am I missing something?


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