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From: Fabio Checconi <fchecconi@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Ryo Tsuruta <ryov@valinux.co.jp>,
	vgoyal@redhat.com, linux-kernel@vger.kernel.org,
	dm-devel@redhat.com, jens.axboe@oracle.com, agk@redhat.com,
	akpm@linux-foundation.org, nauman@google.com,
	guijianfeng@cn.fujitsu.com, jmoyer@redhat.com,
	balbir@linux.vnet.ibm.com
Subject: Re: Regarding dm-ioband tests
Date: Wed, 9 Sep 2009 02:09:00 +0200	[thread overview]
Message-ID: <20090909000900.GK17468@gandalf.sssup.it> (raw)
In-Reply-To: <4AA6AF58.3050501@redhat.com>

Hi,

> From: Rik van Riel <riel@redhat.com>
> Date: Tue, Sep 08, 2009 03:24:08PM -0400
>
> Ryo Tsuruta wrote:
> >Rik van Riel <riel@redhat.com> wrote:
> 
> >>Are you saying that dm-ioband is purposely unfair,
> >>until a certain load level is reached?
> >
> >Not unfair, dm-ioband(weight policy) is intentionally designed to
> >use bandwidth efficiently, weight policy tries to give spare bandwidth
> >of inactive groups to active groups.
> 
> This sounds good, except that the lack of anticipation
> means that a group with just one task doing reads will
> be considered "inactive" in-between reads.
> 

  anticipation helps in achieving fairness, but CFQ currently disables
idling for nonrot+NCQ media, to avoid the resulting throughput loss on
some SSDs.  Are we really sure that we want to introduce anticipation
everywhere, not only to improve throughput on rotational media, but to
achieve fairness too?

  reply	other threads:[~2009-09-09  0:05 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-01 16:50 Vivek Goyal
2009-09-01 17:47 ` Vivek Goyal
2009-09-03 13:11   ` Vivek Goyal
2009-09-04  1:12     ` Ryo Tsuruta
2009-09-15 21:40       ` dm-ioband fairness in terms of sectors seems to be killing disk (Was: Re: Regarding dm-ioband tests) Vivek Goyal
2009-09-16 11:10         ` dm-ioband fairness in terms of sectors seems to be killing disk Ryo Tsuruta
2009-09-04  4:02 ` Regarding dm-ioband tests Ryo Tsuruta
2009-09-04 23:11   ` Vivek Goyal
2009-09-07 11:02     ` Ryo Tsuruta
2009-09-07 13:53       ` Rik van Riel
2009-09-08  3:01         ` Ryo Tsuruta
2009-09-08  3:22           ` Balbir Singh
2009-09-08  5:05             ` Ryo Tsuruta
2009-09-08 13:49               ` Vivek Goyal
2009-09-09  5:17                 ` Ryo Tsuruta
2009-09-09 13:34                   ` Vivek Goyal
2009-09-08 13:42           ` Vivek Goyal
2009-09-08 16:30             ` Nauman Rafique
2009-09-08 16:47               ` Rik van Riel
2009-09-08 17:54                 ` Vivek Goyal
2009-09-15 23:37                   ` ioband: Writer starves reader even without competitors (Re: Regarding dm-ioband tests) Vivek Goyal
2009-09-16 12:08                     ` ioband: Writer starves reader even without competitors Ryo Tsuruta
2009-09-08 17:06             ` Regarding dm-ioband tests Dhaval Giani
2009-09-09  6:05               ` Ryo Tsuruta
2009-09-09 10:51                 ` Dhaval Giani
2009-09-10  7:58                   ` Ryo Tsuruta
2009-09-11  9:53                     ` Dhaval Giani
2009-09-15 15:12                       ` Ryo Tsuruta
2009-09-15 15:19                         ` Balbir Singh
2009-09-15 15:58                           ` Rik van Riel
2009-09-15 16:21                           ` Ryo Tsuruta
2009-09-09 13:57                 ` Vivek Goyal
2009-09-10  3:06                   ` Ryo Tsuruta
2009-09-09 10:01             ` Ryo Tsuruta
2009-09-09 14:31               ` Vivek Goyal
2009-09-10  3:45                 ` Ryo Tsuruta
2009-09-10 13:25                   ` Vivek Goyal
2009-09-08 19:24           ` Rik van Riel
2009-09-09  0:09             ` Fabio Checconi [this message]
2009-09-09  2:06               ` Vivek Goyal
2009-09-09 15:41                 ` Fabio Checconi
2009-09-09 17:30                   ` Vivek Goyal
2009-09-09 19:01                     ` Fabio Checconi
2009-09-09  9:24               ` Ryo Tsuruta
2009-09-16  4:45       ` ioband: Limited fairness and weak isolation between groups (Was: Re: Regarding dm-ioband tests) Vivek Goyal
2009-09-18  7:33         ` ioband: Limited fairness and weak isolation between groups Ryo Tsuruta

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