linux-kernel - Re: [PATCH v3 2/7] sched: accumulate per-cfs

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Message-ID: <20101013135902.GA4189@balbir.in.ibm.com>
Date:	Wed, 13 Oct 2010 19:29:02 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Nikhil Rao <ncrao@...gle.com>
Cc:	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org,
	Dhaval Giani <dhaval.giani@...il.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Herbert Poetzl <herbert@...hfloor.at>,
	Avi Kivity <avi@...hat.com>,
	Chris Friesen <cfriesen@...tel.com>,
	Paul Menage <menage@...gle.com>,
	Mike Waychison <mikew@...gle.com>, Paul Turner <pjt@...gle.com>
Subject: Re: [PATCH v3 2/7] sched: accumulate per-cfs_rq cpu usage

* Nikhil Rao <ncrao@...gle.com> [2010-10-13 06:46:18]:

> > Quick question for cfs_b->quota == RUNTIME_INF, won't cfs_b->runtime
> > be always > 0?
> 
> Hi Balbir,
> 
> cfs_b->runtime can be 0 if the task group exhausts its quota.
> cfs_b->runtime is a counter that is periodically refreshed to
> cfs_b->quota, and is decremented every time a cfs_rq requests a slice.
>

Thanks, Nikhil

I saw several checks for quota == RUNTIME_INF and saw updates not
happening. Do we track usage for cgroups with infinite quota? IOW, is
runtime updated? If so, why?

-- 
	Three Cheers,
	Balbir
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