linux-kernel - Re: [patch v4 11/18] sched: log the cpu utilization at rq

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Date:	Thu, 14 Feb 2013 11:10:23 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	torvalds@...ux-foundation.org, mingo@...hat.com,
	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
Subject: Re: [patch v4 11/18] sched: log the cpu utilization at rq

On 02/12/2013 06:39 PM, Peter Zijlstra wrote:
> On Thu, 2013-01-24 at 11:06 +0800, Alex Shi wrote:
>>
>> The cpu's utilization is to measure how busy is the cpu.
>>         util = cpu_rq(cpu)->avg.runnable_avg_sum
>>                 / cpu_rq(cpu)->avg.runnable_avg_period;
>>
>> Since the util is no more than 1, we use its percentage value in later
>> caculations. And set the the FULL_UTIL as 100%.
>>
>> In later power aware scheduling, we are sensitive for how busy of the
>> cpu, not how much weight of its load. As to power consuming, it is more
>> related with cpu busy time, not the load weight.
> 
> I think we can make that argument in general; that is irrespective of
> the actual policy. We simply never had anything better to go with.
> 
> So please clarify why you think this only applies to power aware
> scheduling.

Um, the rq->util is a general argument. It can be used on any other
places if needed, not power aware scheduling specific.
> 


-- 
Thanks
    Alex
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