Re: [Xen-users] Xen hard-disk performance regression?

[Fabiano Francesconi <fabiano.francesconi@xxxxxxxxx>]

On Mon, Apr 12, 2010 at 01:01:38AM +0200, Olivier B. wrote:
> Hi,
> 
> Are you using LVM ? Barriers was implemented on LVM in recent versions, 
> which can probably explain some performance regressions like this.
> 
> Olivier
> 

Yes, as a matter of fact, but not for those partitions.
Those are simply 4 partitions:

/dev/xvdb1               1       71799   576725436   83  Linux
/dev/xvdb2           71800       97908   209720542+  83  Linux
/dev/xvdb3           97909      117490   157292415   83  Linux
/dev/xvdb4          117491      121601    33021607+  83  Linux

each one formatted with XFS filesystem.

Another guess I made is about the destination fs' fragmentation (that's
about 90%). But this shouldn't affect the performance of only one
kernel.

It is so strange.

> On 11/04/2010 21:44, Fabiano Francesconi wrote:
> > Ok, confirmed. The problem is only visible when copying files so it's
> > not something related to the hard-disk itself.
> >
> > I sincerely don't know how to dig into this but I have made some tests
> > myself.
> >
> > I've tried copying a single avi file (350mb) from one partition to
> > another one. Both partition are on the same device (WDC WD10EADS-00M2B0)
> > and both formatted in XFS filesystem.
> >
> > Running 2.6.32-xen-r1 I have the following output:
> >
> > real        1m35.001s
> > user        0m0.016s
> > sys 0m0.722s
> >
> > Running 2.6.29-xen-r4 I have, instead, the following output:
> >
> > real        0m20.689s
> > user        0m0.018s
> > sys 0m2.047s
> >
> > How can I see such a difference? Is there some known regression for XFS
> > filesystem? I might try to run a vanilla kernel instead of a xen-patched
> > one.
> >
> > Any suggestion will be very much appreciated.
> >
> >    
> 
> 
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-- 
Fabiano Francesconi [GPG key: 0x81E53461]

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