From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs-masters@oss.sgi.com, xfs@oss.sgi.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
T?r?k Edwin <edwintorok@gmail.com>
Subject: Re: XFS internal error (memory corruption)
Date: Wed, 6 Jul 2011 03:07:56 -0400 [thread overview]
Message-ID: <20110706070756.GA25800@infradead.org> (raw)
In-Reply-To: <20110706040403.GW1026@dastard>
On Wed, Jul 06, 2011 at 02:04:03PM +1000, Dave Chinner wrote:
> > Although is there supposed to be a performance benefit from having
> > a separate log disk with XFS?
>
> There used to be. Now everyone just uses delayed logging, which is
> far faster and more scalable that even using an external log.
Even with delayed logging external logs are a huge benefit if you
hit the log hard, e.g. for fsync intensive workloads. E.g. when
using fs_mark in fsync mode it gives speedups over 100% for the
setups I've tested. You'll see similar speedups for NFS server
loads that are log force heavy as well.
>
> > IIRC it has a disadvantage that you can't use barriers properly.
>
> That mostly works now (recent kernels), but you take a hit in
> journal IO waiting synchronously for the data device caches to be
> flushed before writing to the log device.
For metadata-heavy workloads where an external log benefits you most
you generally just want to disable the volatile write cache anyway.
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next prev parent reply other threads:[~2011-07-06 7:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-05 6:03 XFS internal error (memory corruption) Török Edwin
2011-07-05 13:09 ` Dave Chinner
2011-07-05 13:38 ` Török Edwin
2011-07-06 4:04 ` Dave Chinner
2011-07-06 7:07 ` Christoph Hellwig [this message]
2011-07-06 7:22 ` Dave Chinner
2011-07-06 8:05 ` Christoph Hellwig
2011-07-06 22:04 ` Stan Hoeppner
2011-07-06 19:30 ` Stan Hoeppner
2011-07-06 23:52 ` Dave Chinner
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