From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Mark Tinguely <tinguely@sgi.com>,
xfs@oss.sgi.com
Subject: Re: [PATCH v2 1/3] xfs: use b_maps[] for discontiguous buffers
Date: Fri, 30 Nov 2012 18:09:38 -0500 [thread overview]
Message-ID: <20121130230938.GB12674@infradead.org> (raw)
In-Reply-To: <20121130222110.GB12955@dastard>
On Sat, Dec 01, 2012 at 09:21:10AM +1100, Dave Chinner wrote:
> > eeek. yep, I will loop through and count the pages needed in each
> > segment.
>
> That's wrong - the pages must be mappable as a contiguous memory
> range. That's how this code avoids copying the data from
> discontiguous page ranges into a contiguous mapped memory range.
> If you separate each IO into to it's own set of pages, then you have
> to completely rewrite _xfs_buf_ioapply(), which AFAICT works just
> fine with the page allocation that is done right now....
Yeah, you're right.
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next prev parent reply other threads:[~2012-11-30 23:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-28 22:23 [PATCH v2 0/3] discontiguous buffer patches Mark Tinguely
2012-11-28 22:23 ` [PATCH v2 1/3] xfs: use b_maps[] for discontiguous buffers Mark Tinguely
2012-11-30 16:09 ` Christoph Hellwig
2012-11-30 17:55 ` Mark Tinguely
2012-11-30 22:21 ` Dave Chinner
2012-11-30 23:09 ` Christoph Hellwig [this message]
2012-11-30 22:18 ` Dave Chinner
2012-12-02 23:31 ` Dave Chinner
2012-11-28 22:23 ` [PATCH v2 2/3] xfs: fix the buffer log format for contiguous buffers Mark Tinguely
2012-12-02 23:46 ` Dave Chinner
2012-11-28 22:23 ` [PATCH v2 3/3] xfs: fix the multi-segment log buffer format Mark Tinguely
2012-11-30 23:14 ` Christoph Hellwig
2012-12-02 23:52 ` Dave Chinner
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