Le 12/12/2011 03:00, Xupeng Yun a écrit :
On Mon, Dec 12, 2011 at 09:00, Dave Chinner <david@xxxxxxxxxxxxx
<mailto:david@xxxxxxxxxxxxx>> wrote:
Oh, of course, now I remember what the problem is - it's a locking
issue that was fixed in 3.0.11, 3.1.5 and 3.2-rc1.
Got it, thanks.
--
Xupeng Yun
http://about.me/xupeng
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I'm seeing more or less the same here.
Generally speaking XFS code in recent kernels seems to decrease CPU
usage and be faster, which is a very good thing (good works, guy). But...
On two particular server, with recent kernels, I experience a much
higher load than expected, but it's very hard to tell what's wrong. The
system seems more in I/O wait. Older kernels (2.6.32.xx and 2.6.26.xx)
gives better results.
Following this thread, I thought I have the same problems, but it's
probably not the case, as I have tested 2.6.38.xx, 3.0.13, 3.1.5 with
same results.
Thoses servers are mail (dovecot) servers, with lots of simultaneous
imap clients (5000+) an lots of simultaneous message delivery.
These are linux-vservers, on top of LVM volumes. The storage is SAN with
15k RPM SAS drives (and battery backup).
I know barriers were disabled in older kernels, so with recents kernels,
XFS volumes were mounted with nobarrier.
As those servers are critical for us, I can't really test, hardly give
you more precise numbers, and I don't know how to accurately reproduce
this platform to test what's wrong. I know this is NOT a precise bug
report and it won't help much.
All I can say IS :
- read operations seems no slower with recent kernels, backups take
approximatively the same time ;
- I'd say (but I have no proof) that delivery of new mails takes more
time and is more synchronous than before, like nobarrier have no effect.
Does this ring a bell to some of you ?
Thanks,
--
Yann Dupont - Service IRTS, DSI Université de Nantes
Tel : 02.53.48.49.20 - Mail/Jabber : Yann.Dupont@xxxxxxxxxxxxxx
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