Re: [PATCH 8/8] mm: vmscan: Do not writeback filesystem pages from kswapd

Mel Gorman
2011-08-03T13:58:48Z

On Wed, Aug 03, 2011 at 01:37:06PM +0200, Johannes Weiner wrote:
> 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.
>

Yes.

> 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.
>

Yes.

> 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 <jweiner@redhat.com>

I've already dropped the patch. If I could, I would have signed this at
the time as

Signed-off-but-naking-it-anyway: Mel Gorman <mgorman@suse.de

--
Mel Gorman
SUSE Labs