From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com, Alex Elder <aelder@sgi.com>
Subject: Re: [PATCH 04/11] xfs: call xfs_buf_delwri_queue directly
Date: Fri, 2 Sep 2011 10:17:47 +1000 [thread overview]
Message-ID: <20110902001747.GR32358@dastard> (raw)
In-Reply-To: <20110901214640.GB4579@infradead.org>
On Thu, Sep 01, 2011 at 05:46:40PM -0400, Christoph Hellwig wrote:
> On Thu, Sep 01, 2011 at 02:22:15PM -0500, Alex Elder wrote:
> > that the buffer should be queued at unlock time, we now
> > just put it in the queue right away. Seems reasonable.
> > Do you know why enqueueing it was delayed before?
>
> I don't know why - it's a carryover from IRIX days,
Right. On Irix a buffer could simply have the BUF_DELWRI flag set on
it, and the buffer cache would take care of everything else. There
wasn't a specific delayed write list in Irix, instead there was a
fixed table of buffers (large!) that was scanned every 5 seconds
(20% scanned once per second) and the delwri buffers were gathered
by the scan. Hence there were places in XFS where it simply set the
flag to mark a buffer delwri, and that's what this Linux code had to
catch.
> so long before my time.
The XFS code long predates me, too, but I spend a couple of years in
the trenches around the Irix buffer cache when I was at SGI so I at
least know why it was like that. ;)
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-09-02 0:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 8:28 [PATCH 00/11] patch queue for Linux 3.2 Christoph Hellwig
2011-08-23 8:28 ` [PATCH 01/11] xfs: remove delwri buffer handling from xfs_buf_iorequest Christoph Hellwig
2011-09-01 19:21 ` Alex Elder
2011-08-23 8:28 ` [PATCH 02/11] xfs: remove the unlock argument to xfs_buf_delwri_queue Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-09-01 21:39 ` Christoph Hellwig
2011-08-23 8:28 ` [PATCH 03/11] xfs: move more delwri setup into xfs_buf_delwri_queue Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 04/11] xfs: call xfs_buf_delwri_queue directly Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-09-01 21:46 ` Christoph Hellwig
2011-09-02 0:17 ` Dave Chinner [this message]
2011-08-23 8:28 ` [PATCH 05/11] xfs: let xfs_bwrite callers handle the xfs_buf_relse Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 06/11] xfs: use the "delwri" terminology consistently Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 07/11] xfs: remove dead ENODEV handling in xfs_destroy_ioend Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 08/11] xfs: defer AIO/DIO completions Christoph Hellwig
2011-08-24 0:01 ` Dave Chinner
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 09/11] xfs: reduce ioend latency Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 10/11] xfs: wait for I/O completion when writing out pages in xfs_setattr_size Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
2011-08-23 8:28 ` [PATCH 11/11] xfs: remove i_iocount Christoph Hellwig
2011-09-01 19:22 ` Alex Elder
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