On Mon, Jun 14, 2010 at 05:13:37PM -0400, Rik van Riel wrote:

On 06/14/2010 07:17 AM, Mel Gorman wrote:

quoted

Page reclaim cleans individual pages using a_ops->writepage() because from
the VM perspective, it is known that pages in a particular zone must be freed
soon, it considers the target page to be the oldest and it does not want
to wait while background flushers cleans other pages. From a filesystem
perspective this is extremely inefficient as it generates a very seeky
IO pattern leading to the perverse situation where it can take longer to
clean all dirty pages than it would have otherwise.

Reclaiming clean pages should be fast enough that this should
make little, if any, difference.

Indeed, this was a bit weak. The original point of the patch was to write
contiguous pages belonging to the same inode when they were encountered in
that batch which made a bit more sense but didn't work out at first
pass.

quoted

This patch queues all dirty pages at once to maximise the chances that
the write requests get merged efficiently. It also makes the next patch
that avoids writeout from direct reclaim more straight-forward.

However, this is a convincing argument :)

Thanks.

quoted

Signed-off-by: Mel Gorman<redacted>

Reviewed-by: Rik van Riel <redacted>

Thanks again :)

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>