On Thu, Jul 21, 2011 at 05:28:50PM +0100, Mel Gorman wrote:

Assuming that flusher threads will always write back dirty pages promptly
then it is always faster for reclaimers to wait for flushers. This patch
prevents kswapd writing back any filesystem pages.

Signed-off-by: Mel Gorman <mgorman@suse.de>

Relying on the flushers may mean that every dirty page in the system
has to be written back before the pages from the zone of interest are
clean.

De-facto we have only one mechanism to stay on top of the dirty pages
from a per-zone perspective, and that is single-page writeout from
reclaim.

While we all agree that this sucks, we can not remove it unless we
have a replacement that makes zones reclaimable in a reasonable time
frame (or keep them reclaimable in the first place, what per-zone
dirty limits attempt to do).

As such, please include

Nacked-by: Johannes Weiner [off-list ref]

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