linux-kernel - Re: [patch v5 01/15] sched: set initial value for runnable avg of sched entities.

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Date:	Mon, 18 Feb 2013 17:16:11 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
CC:	torvalds@...ux-foundation.org, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
	pjt@...gle.com, namhyung@...nel.org, efault@....de,
	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, morten.rasmussen@....com
Subject: Re: [patch v5 01/15] sched: set initial value for runnable avg of
 sched entities.

On 02/18/2013 04:28 PM, Joonsoo Kim wrote:
> On Mon, Feb 18, 2013 at 01:07:28PM +0800, Alex Shi wrote:
>> > We need initialize the se.avg.{decay_count, load_avg_contrib} to zero
>> > after a new task forked.
>> > Otherwise random values of above variables cause mess when do new task
> I think that these are not random values. In arch_dup_task_struct(),
> we do '*dst = *src', so, these values come from parent process. If we use
> these value appropriately, we can anticipate child process' load easily.
> So to initialize the load_avg_contrib to zero is not good idea for me.

Um, for a new forked task, calling them random value is appropriate,
since uncertain value of decay_count make random behaviour in
enqueue_entity_load_avg().
And many comments said new forked task need not follow parent's
utilisations, like what's you claimed for exec.

-- 
Thanks Alex
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