From: Josef Bacik <jbacik@fusionio.com>
To: "Swâmi Petaramesh" <swami@petaramesh.org>
Cc: Josef Bacik <JBacik@fusionio.com>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: BTRFS, getting darn slower everyday
Date: Mon, 8 Oct 2012 12:31:22 -0400 [thread overview]
Message-ID: <20121008163122.GB2259@localhost.localdomain> (raw)
In-Reply-To: <5072FC37.8090105@petaramesh.org>
On Mon, Oct 08, 2012 at 10:15:51AM -0600, Swâmi Petaramesh wrote:
> Le 08/10/2012 18:09, Josef Bacik a écrit :
> > Can you get sysrq+w when you are seeing slowness? Usually bootup slow times
> > means you don't have space_cache enabled or your cache is being evicted for some
> > reason, can you check dmesg after bootup for messages related to space cache?
> > Thanks,
> I have a few :
>
> Oct 8 15:27:26 tethys kernel: [16174.736603] btrfs: free space inode
> generation (0) did not match free space cache generation (106988)
> Oct 8 15:27:27 tethys kernel: [16175.976784] btrfs: free space inode
> generation (0) did not match free space cache generation (30727)
> Oct 8 15:27:28 tethys kernel: [16176.420719] btrfs: free space inode
> generation (0) did not match free space cache generation (48040)
> Oct 8 15:27:28 tethys kernel: [16176.710972] btrfs: free space inode
> generation (0) did not match free space cache generation (30745)
>
> ...in syslog, but that's about all... and not during boot...
>
> I used to have much much more of these in syslog, but solved it by
> booting once with the "clear_cache" option, that caused boot to be
> extremely slow, but seemed to fix it...
>
> (Remember I have such issues on several machines, it is highly
> improbable that all of them would get their cache ignored...?)
Well what happens is on a actually used fs it ends up being more fragmented than
the amount we're allowed to preallocate for our space cache, and so we don't
write anything out, so it's very likely that all of your machines could be
hitting that. I put a patch into 3.6 to increase the cache size so that
wouldn't happen as much, perhaps move to 3.6 and see if you see some
improvements? Thanks,
Josef
prev parent reply other threads:[~2012-10-08 16:31 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-07 9:26 BTRFS, getting darn slower everyday Swâmi Petaramesh
2012-10-07 10:59 ` Martin Steigerwald
2012-10-07 14:05 ` Swâmi Petaramesh
2012-10-07 14:48 ` Martin Steigerwald
2012-10-08 6:16 ` Swâmi Petaramesh
2012-12-09 5:17 ` Jan Engelhardt
2012-12-09 10:13 ` Martin Steigerwald
2012-12-09 10:41 ` Roman Mamedov
2012-12-09 11:20 ` Swâmi Petaramesh
2012-12-09 11:38 ` Hugo Mills
2012-12-09 22:51 ` Bob Marley
2012-12-09 14:38 ` Jan Engelhardt
2012-10-07 11:02 ` Martin Steigerwald
2012-10-07 12:33 ` Alex
2012-10-07 13:19 ` Swâmi Petaramesh
2012-10-07 14:44 ` Martin Steigerwald
2012-10-07 22:47 ` Goffredo Baroncelli
2012-10-08 6:08 ` Swâmi Petaramesh
2012-10-08 11:38 ` Goffredo Baroncelli
2012-10-08 13:36 ` Swâmi Petaramesh
2012-10-08 15:50 ` Swâmi Petaramesh
2012-10-08 16:46 ` Goffredo Baroncelli
2012-10-08 6:22 ` Swâmi Petaramesh
2012-11-14 16:17 ` Peter Maloney
2012-10-07 13:00 ` Martin Steigerwald
2012-10-07 13:14 ` Swâmi Petaramesh
2012-10-07 14:41 ` Martin Steigerwald
2012-10-08 16:09 ` Josef Bacik
2012-10-08 16:15 ` Swâmi Petaramesh
2012-10-08 16:31 ` Josef Bacik [this message]
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