On Fri, May 09, 2008 at 08:08:41PM -0700, Christoph Lameter wrote:
quoted text
> Defragmentation support for buffer heads. We convert the references to
> buffers to struct page references and try to remove the buffers from
> those pages. If the pages are dirty then trigger writeout so that the
> buffer heads can be removed later.

Oh, no, please don't trigger more random single page writeback from
memory reclaim.  We shoul dbe killing the VM's use of ->writepage,
not encouraging it.

If you are going to clean bufferheads (or pages), please clean entire
mappings via ->writepages as it leads to far superior I/O patterns
and a far higher aggregate rate of page cleaning.....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group
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