From: Karsten Weiss <K.Weiss@science-computing.de>
To: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: Bad ext4 sync performance on 16 TB GPT partition
Date: Fri, 26 Feb 2010 16:47:04 +0100 (CET) [thread overview]
Message-ID: <alpine.LNX.2.00.1002261546380.18232@wong.science-computing.de> (raw)
In-Reply-To: <87ljegb4ow.fsf@openvz.org>
Hi Dmitry!
On Fri, 26 Feb 2010, Dmitry Monakhov wrote:
> > Kernels:
> > * 2.6.18-164.11.1.el5 x86_64 (latest CentOS 5.4 kernel)
> > * 2.6.18-190.el5 x86_64 (latest Red Hat EL5 test kernel I've found from
> > http://people.redhat.com/jwilson/el5/ which contains an ext4 version
> > which (according to the rpm's changelog) was updated from the 2.6.32
> > ext4 codebase.
> Hmm.. It is hard to predict differences between vanilla tree.
> This is no only ext4 related. writeback path is changed dramatically.
> It is not easy to port writeback code to 2.6.18 with full performance
> improvements but without introducing new issues.
> > * I did not try a vanilla kernel so far.
> IMHO It would be really good to know vanilla kernel's stats.
I did a quick&dirty compilation of vanilla kernel 2.6.33 and repeated the
test:
# /usr/bin/time bash -c "dd if=/dev/zero of=/mnt/large/10GB bs=1M count=10000 && sync"
10000+0 records in
10000+0 records out
10485760000 bytes (10 GB) copied, 50.044 seconds, 210 MB/s
0.01user 13.76system 1:04.75elapsed 21%CPU (0avgtext+0avgdata 6224maxresident)k
0inputs+0outputs (0major+1049minor)pagefaults 0swaps
=> The problem shows only with the CentOS / Red Hat 5.4 kernels (including
RH's test kernel 2.6.18-190.el5). Aadmittedly ext4 is only a technology
preview in 5.4...
I've also tried the latest CentOS 5.3 kernel-2.6.18-128.7.1.el5 but
couldn't mount the device (with -t ext4dev).
2.6.18-164.el5 (the initial CentOS 5.4 kernel) has the bug, too.
I'm willing to test patches if somebody wants to debug the problem.
--
Karsten Weiss
next prev parent reply other threads:[~2010-02-26 15:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-26 10:18 Bad ext4 sync performance on 16 TB GPT partition Karsten Weiss
2010-02-26 11:33 ` Karsten Weiss
2010-02-26 11:46 ` Dmitry Monakhov
2010-02-26 15:47 ` Karsten Weiss [this message]
2010-02-26 17:49 ` Eric Sandeen
2010-03-01 8:57 ` Karsten Weiss
2010-03-01 16:22 ` Eric Sandeen
2010-03-12 11:37 ` Karsten Weiss
2010-03-12 15:20 ` Eric Sandeen
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