linux-kernel - Re: CFS Bandwidth Control - Test results of cgroups tasks pinned vs unpinnede

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Date:	Fri, 9 Sep 2011 18:56:37 +0530
From:	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Paul Turner <pjt@...gle.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Vladimir Davydov <vdavydov@...allels.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	Dhaval Giani <dhaval.giani@...il.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Pavel Emelianov <xemul@...allels.com>
Subject: Re: CFS Bandwidth Control - Test results of cgroups tasks pinned vs
 unpinnede

* Peter Zijlstra <a.p.zijlstra@...llo.nl> [2011-09-09 14:31:02]:

> > We have setup cgroups and their hard limits so that in theory they should
> > consume the entire capacity available on machine, leading to 0% idle time.
> > That's not what we see. A more detailed description of the setup and the problem
> > is here:
> > 
> > https://lkml.org/lkml/2011/6/7/352
> 
> That's frigging irrelevant isn't it? A patch should contain its own
> justification.

Agreed my bad. I was (wrongly) setting the problem context by posting
this in response to Paul's email where the problem was discussed.

> > One
> > possibility is to make the idle load balancer become aggressive in
> > pulling tasks across sched-domain boundaries i.e when a CPU becomes idle
> > (after a task got throttled) and invokes the idle load balancer, it
> > should try "harder" at pulling a task from far-off cpus (across
> > package/node boundaries)?
> 
> How about we just live with it?

I think we will, unless the load balancer can be improved (which seems unlikely 
to me :-()

- vatsa

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