Re: [PATCH 02/20] blkio: Change CFQ to use CFS like queue time stamps

From: Corrado Zoccolo <czoccolo@gmail.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-kernel@vger.kernel.org, jens.axboe@oracle.com,
	nauman@google.com, dpshah@google.com, lizf@cn.fujitsu.com,
	ryov@valinux.co.jp, fernando@oss.ntt.co.jp,
	s-uchida@ap.jp.nec.com, taka@valinux.co.jp,
	guijianfeng@cn.fujitsu.com, jmoyer@redhat.com,
	balbir@linux.vnet.ibm.com, righi.andrea@gmail.com,
	m-ikeda@ds.jp.nec.com, akpm@linux-foundation.org,
	riel@redhat.com, kamezawa.hiroyu@jp.fujitsu.com
Subject: Re: [PATCH 02/20] blkio: Change CFQ to use CFS like queue time stamps
Date: Wed, 4 Nov 2009 22:18:15 +0100	[thread overview]
Message-ID: <4e5e476b0911041318w68bd774qf110d1abd7f946e4@mail.gmail.com> (raw)
In-Reply-To: <1257291837-6246-3-git-send-email-vgoyal@redhat.com>

Hi Vivek,
On Wed, Nov 4, 2009 at 12:43 AM, Vivek Goyal <vgoyal@redhat.com> wrote:
> o Previously CFQ had one service tree where queues of all theree prio classes
>  were being queued. One side affect of this time stamping approach is that
>  now single tree approach might not work and we need to keep separate service
>  trees for three prio classes.
>
Single service tree is no longer true in cfq for-2.6.33.
Now we have a matrix of service trees, with first dimension being the
priority class, and second dimension being the workload type
(synchronous idle, synchronous no-idle, async).
You can have a look at the series: http://lkml.org/lkml/2009/10/26/482 .
It may have other interesting influences on your work, as the idle
introduced at the end of the synchronous no-idle tree, that provides
fairness also for seeky or high-think-time queues.

Corrado