From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: force buffer writeback before blocking on the ilock in inode reclaim
Date: Sun, 20 Nov 2011 19:33:45 +1100 [thread overview]
Message-ID: <20111120083345.GO7046@dastard> (raw)
In-Reply-To: <20111120072334.GA27386@infradead.org>
On Sun, Nov 20, 2011 at 02:23:34AM -0500, Christoph Hellwig wrote:
> If we are doing synchronous inode reclaim we block the VM from making
> progress in memory reclaim. So if we encouter a flush locked inode
> make sure we force out all delayed buffers ASAP to speed up the wait
> for it to be unlocked. Without this we can get hangs of up to 30
> seconds during workloads hitting synchronous inode reclaim.
I don't think we need to push out all delayed buffers - that's an
awfully big sledge hammer to get a single buffer moving. Indeed, we
already have a mechanism for dealing with this problem -
xfs_buf_delwri_promote() - when we hit it during AIL flushing.
IOWs, we only need to promote the buffer the inode sits in and kick
xfsbufd. that is, something like:
bp = xfs_incore(ip->i_mount->m_ddev_targp, iip->ili_format.ilf_blkno,
iip->ili_format.ilf_len, XBF_TRYLOCK);
if (bp && XFS_BUF_ISDELAYWRITE(bp)) {
xfs_buf_delwri_promote(bp);
wake_up_process(mp->m_ddev_targp->bt_task);
}
if (bp)
xfs_buf_relse(bp);
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-11-20 8:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-20 7:23 [PATCH] xfs: force buffer writeback before blocking on the ilock in inode reclaim Christoph Hellwig
2011-11-20 7:59 ` Christoph Hellwig
2011-11-20 8:33 ` Dave Chinner [this message]
2011-11-20 11:46 ` Christoph Hellwig
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