WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] 2.4.29-xenU VBD performance (problem)

To: Pasi Kärkkäinen <pasik@xxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] 2.4.29-xenU VBD performance (problem)
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Tue, 15 Feb 2005 04:08:17 -0000
Cc: <ian.pratt@xxxxxxxxxxxx>
Delivery-date: Tue, 15 Feb 2005 04:11:09 +0000
Envelope-to: xen+James.Bulpin@xxxxxxxxxxxx
List-archive: <http://sourceforge.net/mailarchive/forum.php?forum=xen-devel>
List-help: <mailto:xen-devel-request@lists.sourceforge.net?subject=help>
List-id: List for Xen developers <xen-devel.lists.sourceforge.net>
List-post: <mailto:xen-devel@lists.sourceforge.net>
List-subscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=subscribe>
List-unsubscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=unsubscribe>
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
Thread-index: AcUSkHp7ZRWLKr+rQbCAq+tEwQrYnwAJ78tg
Thread-topic: [Xen-devel] 2.4.29-xenU VBD performance (problem)
> In dom0 (2.6.10-xen0), I'm able to write to lvm-volume at 35 
> - 40 MB/sec
> (megabytes per second). Measured with:
> "sync; date; dd if=/dev/zero of=/dev/vg0/lv0 bs=1024k 
> count=100; sync; date"
> 
> But, under domU (2.4.29-xenU), using that same lvm-volume as 
> VBD, I only get around 
> 10 - 12 MB/sec write performance measured in the same way.

That's very odd -- I see virtually no loss of throughput in a domU.

However, 100MB isn't really enough to get a decent measure as its likely to all 
still be in memory -- sync doesn't do what you think. I usually do measurements 
using a transfer size of 10x the memory of the system.

A couple of other things to try if you still experience poor peformance:
  * use a 2.6 domU
  * use a raw partition rather than LVM

We do most of our testing using 2.6 for everything, so its possible there a 
weird 2.4 domU to 2.6 dom0 performance bug.

Ian


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_ide95&alloc_id396&op=click
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel