Re: [PATCH 07/11] Memory compaction core

[KAMEZAWA Hiroyuki]

On Wed, 24 Mar 2010 10:47:41 +0900
Minchan Kim <minchan.kim@xxxxxxxxx> wrote:

> On Wed, Mar 24, 2010 at 10:03 AM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> > On Tue, 23 Mar 2010 12:25:42 +0000
> > Mel Gorman <mel@xxxxxxxxx> wrote:
> >
> >> This patch is the core of a mechanism which compacts memory in a zone by
> >> relocating movable pages towards the end of the zone.
> >>
> >> A single compaction run involves a migration scanner and a free scanner.
> >> Both scanners operate on pageblock-sized areas in the zone. The migration
> >> scanner starts at the bottom of the zone and searches for all movable pages
> >> within each area, isolating them onto a private list called migratelist.
> >> The free scanner starts at the top of the zone and searches for suitable
> >> areas and consumes the free pages within making them available for the
> >> migration scanner. The pages isolated for migration are then migrated to
> >> the newly isolated free pages.
> >>
> >> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> >> Acked-by: Rik van Riel <riel@xxxxxxxxxx>
> >> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> >
> > I think lru_add_drain() or lru_add_drain_all() should be called somewhere
> > when we do __isolate_lru_page(). But it's (_all is) slow....
> >
> 
> migrate_prep does it.
> 
Thanks.

Hmm...then, lru_add_drain_all() is called at each (32page migrate) itelation.
Isn't it too slow to be called in such frequency ?

Thanks,
-Kame




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