From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: extremely slow syncing on btrfs with 2.6.39.1 Date: Tue, 12 Jul 2011 16:44:31 +0800 Message-ID: <4E1C096F.9020609@cn.fujitsu.com> References: <4E1BF52E.9090100@mobileobjects.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: linux-btrfs@vger.kernel.org To: Lubos Kolouch Return-path: In-Reply-To: List-ID: >>> I've been monitoring the lists for a while now but didn't see this >>> problem mentioned in particular: I've got a fairly standard desktop >>> system at home, 700gb WD drive, nothing special, with 2 btrfs >>> filesystems and some snapshots. The system runs for days, and I've >>> noticed unusual disk activity the other evening - turns out that it's >>> taking forever to sync(). >>> >>> $ uname -r >>> 2.6.39.1 >>> $ grep btrfs /proc/mounts >>> /dev/root / btrfs rw,relatime 0 0 # is /dev/sdb2 # /dev/sdb5 /home >>> btrfs rw,relatime 0 0 $ time sync >>> >>> real 1m5.552s >>> user 0m0.000s >>> sys 0m2.102s >>> >>> $ time sync >>> >>> real 1m16.830s >>> user 0m0.001s >>> sys 0m1.490s >>> >>> $ df -h / /home >>> Filesystem Size Used Avail Use% Mounted on /dev/root 47G >>> 33G 7.7G 82% / /dev/sdb5 652G 216G 421G 34% /home $ btrfs fi >>> df / >>> Data: total=35.48GB, used=29.86GB >>> System, DUP: total=16.00MB, used=12.00KB System: total=4.00MB, >>> used=0.00 >>> Metadata, DUP: total=4.50GB, used=1.67GB >>> $ btrfs fi df /home >>> Data: total=310.01GB, used=209.53GB >>> System, DUP: total=8.00MB, used=48.00KB System: total=4.00MB, used=0.00 >>> Metadata, DUP: total=11.00GB, used=2.98GB Metadata: total=8.00MB, >>> used=0.00 >>> >>> I'll switch to 3.0 soon, but, given the fact that we're going to be >>> running MeeGo on 2.6.39 probably for a while, I was wondering if anyone >>> knows off the top of their heads if this issue is known/identified. If >>> not then I'll need to make someone do some patching ;). >>> >>> Auke >> >> You should read the thread "Abysmal Performance" of these mailing list >> from last month. They had a similar problem and downgraded to a 2.6.38 >> kernel. By the way, that works for me too for the time being. >> >> Best Regards. >> >> Jan Stilow > > I had similar experience with two servers running on 2.6.39 - the > performance was terrible, after downgrade to 2.6.38 the speed is OK again. > Then you can turn to bisection to find out the culprit.