Bad performance with XFS + 2.6.38 / 2.6.39

[Yann Dupont]

Le 21/12/2011 23:26, Dave Chinner a écrit :
> On Wed, Dec 21, 2011 at 06:56:34PM +0100, Yann Dupont wrote:
>> Le 21/12/2011 16:10, Stan Hoeppner a écrit :
>>
>>
>>> 1.  What mailbox format are you using?  Is this a constant or variable?
>>
>> Maildir++
>
> Which is what?

Each message is saved as an individual files. With loaded mailboxex, you 
can end with thousands of files under one directory.

>
> Can you run a block trace on both kernels (for say five minutes)
> when the load differential is showing up and provide that to us so
> we can see how the IO patterns are differing?
>

Yes. Keep in mind that I can have very different load in 5 minutes distance.
I have 2 options here :

Case 1 : For server 1, running with kernel 2.6.26, blktrace it, reboot 
in 3.1.5, blktrace it. OR

Case 2 : Server 1 running 2.6.26 and Server 2 running 3.1.5

in Case 1 you have the same set of users and the same config garantied.

in case 2, you don't have the same set of users, but the load can be 
quite symetric (think of mailing list)


I will go for case 2 I think.

Last question :

The volumes are on top of lvm2 (sitting on top of multipath dm)


I'll try to blktrace the volume itself, but I can end blktracing the 
scsi primary path (don't know if it make a difference)

Is there any option you want in blktrace ???

Thanks,


-- 
Yann Dupont - Service IRTS, DSI Université de Nantes
Tel : 02.53.48.49.20 - Mail/Jabber : Yann.Dupont at univ-nantes.fr