linux-kernel - RE: 2.6.27-rc5 OLTP performance regression

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Message-ID: <BC02C49EEB98354DBA7F5DD76F2A9E8002FE6E7B62@azsmsx501.amr.corp.intel.com>
Date:	Wed, 10 Sep 2008 09:14:27 -0700
From:	"Ma, Chinang" <chinang.ma@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Mike Galbraith <efault@....de>,
	Gregory Haskins <ghaskins@...ell.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	"Wilcox, Matthew R" <matthew.r.wilcox@...el.com>,
	"Tripathi, Sharad C" <sharad.c.tripathi@...el.com>,
	"Chilukuri, Harita" <harita.chilukuri@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: 2.6.27-rc5 OLTP performance regression

I increased the /proc/sys/kernel/sched_shares_ratelimit from 1 millisecond to one second to reduce the frequency of shares update. That was okay for OLTP workload. As Peter mentioned, a larger value will reduce the accuracy of SMP fairness for group scheduler and the ratelimit and using a larger default value may not be good for general case.

Thanks,
Chinang
-----Original Message-----
From: Ingo Molnar [mailto:mingo@...e.hu]
Sent: Wednesday, September 10, 2008 5:26 AM
To: Ma, Chinang
Cc: Peter Zijlstra; Srivatsa Vaddagiri; Mike Galbraith; Gregory Haskins; Steven Rostedt; Nick Piggin; Siddha, Suresh B; Wilcox, Matthew R; Tripathi, Sharad C; Chilukuri, Harita; linux-kernel@...r.kernel.org
Subject: Re: 2.6.27-rc5 OLTP performance regression


* Ma, Chinang <chinang.ma@...el.com> wrote:

> Peter,
>         We increased sched_shares_ratelimit and were able to recover
> the 2% performance regression. [...]

great. Could you please post a patch for that?

        Ingo
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