From: Nick Piggin <npiggin@kernel.dk>
To: Dave Chinner <david@fromorbit.com>
Cc: Nick Piggin <npiggin@kernel.dk>, xfs@oss.sgi.com
Subject: Re: [PATCH] Re: XFS performance oddity
Date: Thu, 25 Nov 2010 15:54:24 +1100 [thread overview]
Message-ID: <20101125045424.GA3532@amd> (raw)
In-Reply-To: <20101124052823.GD22876@dastard>
On Wed, Nov 24, 2010 at 04:28:23PM +1100, Dave Chinner wrote:
> xfs: push stale, pinned buffers on trylock failures
>
> From: Dave Chinner <dchinner@redhat.com>
>
> As reported by Nick Piggin, XFS is suffering from long pauses under
> highly concurrent workloads when hosted on ramdisks. The problem is
> that an inode buffer is stuck in the pinned state in memory and as a
> result either the inode buffer or one of the inodes within the
> buffer is stopping the tail of the log from being moved forward.
>
> The system remains in this state until a periodic log force issued
> by xfssyncd causes the buffer to be unpinned. The main problem is
> that these are stale buffers, and are hence held locked until the
> transaction/checkpoint that marked them state has been committed to
> disk. When the filesystem gets into this state, only the xfssyncd
> can cause the async transactions to be committed to disk and hence
> unpin the inode buffer.
>
> This problem was encountered when scaling the busy extent list, but
> only the blocking lock interface was fixed to solve the problem.
> Extend the same fix to the buffer trylock operations - if we fail to
> lock a pinned, stale buffer, then force the log immediately so that
> when the next attempt to lock it comes around, it will have been
> unpinned.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
No more stalls, thanks.
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prev parent reply other threads:[~2010-11-25 4:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-23 12:24 XFS performance oddity Nick Piggin
2010-11-23 12:30 ` Nick Piggin
2010-11-23 20:58 ` Dave Chinner
2010-11-24 0:50 ` Nick Piggin
2010-11-24 3:15 ` Dave Chinner
2010-11-24 5:28 ` [PATCH] " Dave Chinner
2010-11-25 4:54 ` Nick Piggin [this message]
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