From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 3/5] xfs: always push the AIL to the target
Date: Mon, 9 May 2011 10:13:41 -0400 [thread overview]
Message-ID: <20110509141341.GD12262@infradead.org> (raw)
In-Reply-To: <1304650448-28438-4-git-send-email-david@fromorbit.com>
On Fri, May 06, 2011 at 12:54:06PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> The recent conversion of the xfsaild functionality to a work queue
> introduced a hard-to-hit log space grant hang. One of the problems
> discovered is a target mismatch between the item pushing loop and
> the target itself.
>
> The push trigger checks for the target increasing (i.e. new target >
> current) while the push loop only pushes items that have a LSN <
> current. As a result, we can get the situation where the push target
> is X, the items at the tail of the AIL have LSN X and they don't get
> pushed. The push work then completes thinking it is done, and cannot
> be restarted until the push target increases to >= X + 1. If the
> push target then never increases (because the tail is not moving),
> then we never run the push work again and we stall.
>
> Fix it by making sure log items with a LSN that matches the target
> exactly are pushed during the loop.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
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next prev parent reply other threads:[~2011-05-09 14:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-06 2:54 [PATCH 0/5] xfs: regression fixes for 2.6.39-rc6 Dave Chinner
2011-05-06 2:54 ` [PATCH 1/5] xfs: ensure reclaim cursor is reset correctly at end of AG Dave Chinner
2011-05-09 14:07 ` Christoph Hellwig
2011-05-06 2:54 ` [PATCH 2/5] xfs: exit AIL push work correctly when AIL is empty Dave Chinner
2011-05-09 14:08 ` Christoph Hellwig
2011-05-06 2:54 ` [PATCH 3/5] xfs: always push the AIL to the target Dave Chinner
2011-05-09 14:13 ` Christoph Hellwig [this message]
2011-05-06 2:54 ` [PATCH 5/5] xfs: fix race condition in AIL push trigger Dave Chinner
2011-05-09 14:16 ` Christoph Hellwig
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