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

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Message-ID: <20110913050306.GB7254@linux.vnet.ibm.com>
Date:	Tue, 13 Sep 2011 10:33:06 +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

* Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com> [2011-09-13 09:45:45]:

> * Peter Zijlstra <a.p.zijlstra@...llo.nl> [2011-09-12 14:35:43]:
> 
> > Of course it does.. and I bet you can improve that slightly if you
> > manage to fix some of the numerical nightmares that live in the cgroup
> > load-balancer (Paul, care to share your WIP?)
> 
> Booting with "nohz=off" also helps significantly.
> 
> With nohz=on, average idle time (over 1 min) is 10.3%
> With nohz=off, average idle time (over 1 min) is 3.9%

Tuning min_interval and max_interval of various sched_domains to 1 [a]
and also setting sched_cfs_bandwidth_slice_us to 500 does cut down idle
time further to 2.7% ..

This is perhaps not optimal (as it may lead to more lock contentions), but 
something to note for those who care for both capping and utilization in
equal measure!

- vatsa

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