Re: [RFC 3/8] vmscan: make isolate_lru_page with filter aware

[KAMEZAWA Hiroyuki]

On Thu, 28 Apr 2011 10:54:32 +0200
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> On Wed, Apr 27, 2011 at 05:03:04PM +0900, KAMEZAWA Hiroyuki wrote:
> > On Wed, 27 Apr 2011 01:25:20 +0900
> > Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
> > 
> > > In some __zone_reclaim case, we don't want to shrink mapped page.
> > > Nonetheless, we have isolated mapped page and re-add it into
> > > LRU's head. It's unnecessary CPU overhead and makes LRU churning.
> > > 
> > > Of course, when we isolate the page, the page might be mapped but
> > > when we try to migrate the page, the page would be not mapped.
> > > So it could be migrated. But race is rare and although it happens,
> > > it's no big deal.
> > > 
> > > Cc: Christoph Lameter <cl@xxxxxxxxx>
> > > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> > > Cc: Mel Gorman <mgorman@xxxxxxx>
> > > Cc: Rik van Riel <riel@xxxxxxxxxx>
> > > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> > > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> > 
> > 
> > Hmm, it seems mm/memcontrol.c::mem_cgroup_isolate_pages() should be updated, too.
> 
> memcg reclaim always does sc->may_unmap = 1.  What is there to
> communicate to mem_cgroup_isolate_pages?
>

Hmm, maybe you're right and nothing to do until memcg need to support soft
limit in zone reclaim mode. I hope no more users.

Thanks,
-Kame

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