82 messages in com.xensource.lists.xen-develRe: [Xen-devel] poor domU VBD perform...
FromSent OnAttachments
Peter Bier26 Mar 2005 10:14 
Ian Pratt27 Mar 2005 09:41 
peter bier28 Mar 2005 00:48 
peter bier28 Mar 2005 04:44 
Ian Pratt28 Mar 2005 10:54 
Andrew Theurer28 Mar 2005 11:32 
Ian Pratt28 Mar 2005 12:13 
Andrew Theurer28 Mar 2005 12:17 
Andrew Theurer28 Mar 2005 13:48 
Ian Pratt28 Mar 2005 14:16 
Peter Bier28 Mar 2005 15:38 
Andrew Theurer28 Mar 2005 16:27 
Pasi Kärkkäinen28 Mar 2005 22:19 
Ian Pratt29 Mar 2005 00:13 
peter bier29 Mar 2005 00:43 
peter bier29 Mar 2005 03:39 
Kurt Garloff29 Mar 2005 05:33 
Ian Pratt29 Mar 2005 05:38 
Ian Pratt29 Mar 2005 06:19 
B.G. Bruce29 Mar 2005 06:28 
peter bier29 Mar 2005 07:27 
Andrew Theurer29 Mar 2005 10:39.Other
Steven Hand29 Mar 2005 11:13 
Kurt Garloff29 Mar 2005 14:44.diff
Andrew Theurer29 Mar 2005 14:58 
Kurt Garloff29 Mar 2005 15:19 
Andrew Theurer29 Mar 2005 15:26 
Jens Axboe30 Mar 2005 00:53 
Kurt Garloff30 Mar 2005 02:00 
Ian Pratt30 Mar 2005 03:15 
peter bier30 Mar 2005 09:00 
Andrew Theurer30 Mar 2005 10:04 
Jens Axboe30 Mar 2005 23:04 
Jens Axboe30 Mar 2005 23:10 
Keir Fraser31 Mar 2005 00:17 
Jens Axboe31 Mar 2005 00:18 
Philip R Auld31 Mar 2005 06:32 
Kurt Garloff31 Mar 2005 07:34 
Jens Axboe31 Mar 2005 07:39 
Jens Axboe31 Mar 2005 07:41 
Keir Fraser31 Mar 2005 07:49 
Andrew Theurer31 Mar 2005 08:01 
Nivedita Singhvi31 Mar 2005 08:27 
Philip R Auld31 Mar 2005 08:52 
Philip R Auld31 Mar 2005 08:55 
Jens Axboe31 Mar 2005 09:42 
Jens Axboe31 Mar 2005 09:44 
Ian Pratt31 Mar 2005 09:54 
Jens Axboe31 Mar 2005 10:01 
Jens Axboe31 Mar 2005 10:03 
Kurt Garloff31 Mar 2005 10:27 
Philip R Auld31 Mar 2005 10:42 
Keir Fraser31 Mar 2005 10:57 
Keir Fraser31 Mar 2005 11:07 
Keir Fraser31 Mar 2005 11:10 
Jens Axboe31 Mar 2005 11:19 
Jens Axboe31 Mar 2005 11:21 
Jens Axboe31 Mar 2005 11:21 
Andrew Theurer31 Mar 2005 12:48 
Keir Fraser31 Mar 2005 13:14 
Andrew Theurer31 Mar 2005 13:26 
Ian Pratt31 Mar 2005 13:32 
Nivedita Singhvi31 Mar 2005 13:59 
Andrew Theurer31 Mar 2005 14:13 
Ian Pratt31 Mar 2005 14:36 
Andrew Theurer31 Mar 2005 15:05 
Jens Axboe31 Mar 2005 21:43 
peter bier01 Apr 2005 08:35 
Ian Pratt01 Apr 2005 09:46 
Cédric Schieli01 Apr 2005 13:40 
Ian Pratt01 Apr 2005 15:21 
Cédric Schieli02 Apr 2005 02:36 
Ian Pratt02 Apr 2005 02:56 
Cédric Schieli02 Apr 2005 04:10 
peter bier02 Apr 2005 11:53 
Cédric Schieli03 Apr 2005 08:26 
Ian Pratt03 Apr 2005 09:38 
Cédric Schieli04 Apr 2005 12:13 
Ian Pratt04 Apr 2005 12:36 
Nicholas Lee04 Apr 2005 15:35 
peter bier12 Apr 2005 03:28 
Ian Pratt12 Apr 2005 03:51 
Subject:Re: [Xen-devel] poor domU VBD performance.
From:Andrew Theurer (haba@us.ibm.com)
Date:03/28/2005 12:17:57 PM
List:com.xensource.lists.xen-devel

On Monday 28 March 2005 14:14, Ian Pratt wrote:

I found out that dom0 does file-system IO and raw IO ( using dd as a tool to test throughput from the disk ) is about exactly the same as when using a standard linux kernel without XEN. But the raw IO from DomU to an unused disk ( a second disk in the system ) is limited to fourty percent of the speed I get within Dom0.

Is the second disk exactly the same as the first one? I'll try an IO test here on the same disk array with dom0 and domU and see what I get.

I've reproduced the problem and its a real issue.

It only affects reads, and is almost certainly down to how the blkback driver passes requests down to the actual device.

Does anyone on the list actually understand the changes made to linux block IO between 2.4 and 2.6?

In the 2.6 blkfront there is no run_task_queue() to flush requests to the lower layer, and we use submit_bio() instead of 2.4's generic_make_request(). It looks like this is happening syncronously rather than queueing multiple requests. What should we be doing to cause things to be batched?

There are multiple IO schedulers in 2.6. Do you know which one is being used? It should say somewhere in the boot log. Some read-ahead code also changed in 2.6.10-11 range.

So far I have not been able to reproduce this in xen-unstable with 2.6. I am building xen-2.0.5 for a look.

-Andrew

_______________________________________________ Xen-devel mailing list Xen-@lists.xensource.com http://lists.xensource.com/xen-devel