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From: Mikulas Patocka <mpatocka@redhat.com>
To: device-mapper development <dm-devel@redhat.com>,
	Joe Thornber <thornber@redhat.com>
Cc: "Alasdair G. Kergon" <agk@redhat.com>
Subject: Re: [PATCH 1/2] dm-kcopyd: introduce per-module throttle structure
Date: Tue, 7 Jun 2011 13:50:16 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.64.1106071321300.8279@hs20-bc2-1.build.redhat.com> (raw)
In-Reply-To: <20110603110111.GA4969@ubuntu>



On Fri, 3 Jun 2011, Joe Thornber wrote:

> On Thu, Jun 02, 2011 at 03:55:16PM -0400, Mikulas Patocka wrote:
> > > iv) you haven't explained how the sys admin works out the correct
> > > throttle value.
> > 
> > There is no "correct" value. The "correct" value depends on how important 
> > is copying itself v.s. other i/o.
> 
> So who is going to set this?  Do you really have no advice for them
> beyond 'there is no correct value'?

I did some tests. I did some random and sequential I/O on the same disk 
while mirror was resynchronizing. The result is this:

random read:
mirror throttle / IOs per second
100%	94
75%	113
50%	127
25%	145
idle	160

sequential read:
mirror throttle / throughput MB/s
100%	104
75%	118
50%	122
25%	127
idle	134

Mikulas

  parent reply	other threads:[~2011-06-07 17:50 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-31 22:03 [PATCH 1/2] dm-kcopyd: introduce per-module throttle structure Mikulas Patocka
2011-06-01  6:18 ` Ankit Jain
2011-06-01  7:13   ` Ankit Jain
2011-06-02 19:16   ` Mikulas Patocka
2011-06-01  9:51 ` Joe Thornber
2011-06-02 19:55   ` Mikulas Patocka
2011-06-03 11:01     ` Joe Thornber
2011-06-03 15:54       ` Mike Snitzer
2011-06-07 17:50       ` Mikulas Patocka [this message]
2011-06-09  9:47         ` Joe Thornber
2011-06-09 16:08           ` Mikulas Patocka
2011-06-09 16:27             ` Alasdair G Kergon
2011-06-10  8:44             ` Joe Thornber
2011-06-10  9:28               ` Lars Ellenberg
2011-06-10 10:14                 ` Joe Thornber
2011-06-10 13:41                   ` Mikulas Patocka
2011-06-10 13:48                     ` Joe Thornber
2011-06-10 16:13                       ` Lars Ellenberg
2011-06-10 13:51                     ` Mike Snitzer
2011-06-11 20:27               ` Mikulas Patocka
2011-06-13  9:17                 ` Joe Thornber
2011-06-13 21:06                   ` Mikulas Patocka
2011-06-14  8:34                     ` Joe Thornber

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