Date: Mon, 28 Sep 2009 16:38:11 +0900 (JST)
Message-Id: <20090928.163811.104053649.ryov@valinux.co.jp>
To: riel@redhat.com
Cc: vgoyal@redhat.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       jens.axboe@oracle.com, containers@lists.linux-foundation.org,
       dm-devel@redhat.com, nauman@google.com, dpshah@google.com,
       lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com,
       paolo.valente@unimore.it, fernando@oss.ntt.co.jp,
       s-uchida@ap.jp.nec.com, taka@valinux.co.jp, guijianfeng@cn.fujitsu.com,
       jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com,
       righi.andrea@gmail.com, m-ikeda@ds.jp.nec.com, agk@redhat.com,
       peterz@infradead.org, jmarchan@redhat.com,
       torvalds@linux-foundation.org, mingo@elte.hu
Subject: Re: IO scheduler based IO controller V10
From: Ryo Tsuruta <ryov@valinux.co.jp>
In-Reply-To: <4ABCDBFF.1020203@redhat.com>
References: <20090925050429.GB12555@redhat.com>
	<20090925.180724.104041942.ryov@valinux.co.jp>
	<4ABCDBFF.1020203@redhat.com>
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Hi Rik,

Rik van Riel <riel@redhat.com> wrote:
> Ryo Tsuruta wrote:
> 
> > Because dm-ioband provides faireness in terms of how many IO requests
> > are issued or how many bytes are transferred, so this behaviour is to
> > be expected. Do you think fairness in terms of IO requests and size is
> > not fair?
> 
> When there are two workloads competing for the same
> resources, I would expect each of the workloads to
> run at about 50% of the speed at which it would run
> on an uncontended system.
> 
> Having one of the workloads run at 95% of the
> uncontended speed and the other workload at 5%
> is "not fair" (to put it diplomatically).

As I wrote in the mail to Vivek, I think that providing multiple
policies, on a per disk time basis, on a per iosize basis, maximum
rate limiting or etc would be good for users.

Thanks,
Ryo Tsuruta
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