From: Jeff Mahoney <jeffm@suse.com>
To: Mark Fasheh <mfasheh@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>, xfs@oss.sgi.com
Subject: Re: xfs-trace-ilock-more
Date: Wed, 14 Dec 2011 14:24:32 -0500 [thread overview]
Message-ID: <4EE8F7F0.7070207@suse.com> (raw)
In-Reply-To: <20111214182750.GH11114@wotan.suse.de>
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On 12/14/2011 01:27 PM, Mark Fasheh wrote:
> Hey Christoph,
>
> On Tue, Dec 13, 2011 at 09:40:40PM -0500, Christoph Hellwig wrote:
>> Can you explain the story behid this patch in SLES11SP1?
>
> We were looking at some performance issues and needed a bit more
> information on the amount of time spent in ilock. I can give you
> more specifics if you want, I just have to dig up the e-mails (it's
> been a while).
That's pretty much the explanation. With heavy reader load, buffered
writes were stalling for 80 ms and sometimes longer. I suspected it
was contention on the ilock and the tracing with that patch
demonstrated a delay there. Since we were chasing a similar issue at
another site, it seemed worthwhile to just keep it around. We're still
tracking down the cause. I'm not sure if more recent kernels have the
same issue as there's been quite a lot of churn.
- -Jeff
- --
Jeff Mahoney
SUSE Labs
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next prev parent reply other threads:[~2011-12-14 19:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 2:40 xfs-trace-ilock-more Christoph Hellwig
2011-12-14 18:27 ` xfs-trace-ilock-more Mark Fasheh
2011-12-14 19:24 ` Jeff Mahoney [this message]
2011-12-14 20:32 ` xfs-trace-ilock-more Dave Chinner
2011-12-14 22:42 ` xfs-trace-ilock-more Jeff Mahoney
2011-12-18 20:26 ` xfs-trace-ilock-more Christoph Hellwig
2011-12-18 20:27 ` xfs-trace-ilock-more Christoph Hellwig
2012-01-05 22:38 ` xfs-trace-ilock-more Mark Fasheh
2012-01-05 23:54 ` xfs-trace-ilock-more Dave Chinner
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