On 12/21/2011 3:08 AM, Yann Dupont wrote: > 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 >> >> >> _______________________________________________ >> xfs mailing list >> xfs@xxxxxxxxxxx >> http://oss.sgi.com/mailman/listinfo/xfs > > 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 ? 1. What mailbox format are you using? Is this a constant or variable? 2. Is the Dovecot rev and config the same everywhere, before/after? 3. Are Dovecot instances using NFS to access the XFS volumes? 4. Is this a Dovecot 2.x cluster with director and NFS storage? -- Stan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
