linux-kernel - Re: Do not overload dispatch queue (Was: Re: IO scheduler based IO controller V10)

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Message-Id: <1254578553.7499.5.camel@marge.simson.net>
Date:	Sat, 03 Oct 2009 16:02:33 +0200
From:	Mike Galbraith <efault@....de>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Jens Axboe <jens.axboe@...cle.com>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ulrich Lukas <stellplatz-nr.13a@...enparkplatz.de>,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, dm-devel@...hat.com,
	nauman@...gle.com, dpshah@...gle.com, lizf@...fujitsu.com,
	mikew@...gle.com, fchecconi@...il.com, paolo.valente@...more.it,
	ryov@...inux.co.jp, fernando@....ntt.co.jp, jmoyer@...hat.com,
	dhaval@...ux.vnet.ibm.com, balbir@...ux.vnet.ibm.com,
	righi.andrea@...il.com, m-ikeda@...jp.nec.com, agk@...hat.com,
	akpm@...ux-foundation.org, peterz@...radead.org,
	jmarchan@...hat.com, riel@...hat.com
Subject: Re: Do not overload dispatch queue (Was: Re: IO scheduler based IO
 controller V10)

On Sat, 2009-10-03 at 09:56 -0400, Vivek Goyal wrote:

> I have kept the overload delay period as "cfq_slice_sync" same as Mike had
> done. We shall have to experiment what is a good waiting perioed. Is 100ms
> too long if we are waiting for a request from same process which recently
> finished IO and we did not enable idle on it.
> 
> I guess we can tweak the delay period as we move along.

I kept the delay period very short to minimize possible damage. Without
the idle thing, it wasn't enough, but with, worked a treat, as does your
patch.

	-Mike

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