Re: [PATCH 3/4] vmscan: zone_reclaim use may_swap

Johannes Weiner
2009-05-13T11:29:19Z

On Wed, May 13, 2009 at 12:07:30PM +0900, KOSAKI Motohiro wrote:
> Subject: [PATCH] vmscan: zone_reclaim use may_swap
>
> Documentation/sysctl/vm.txt says
>
> zone_reclaim_mode:
>
> Zone_reclaim_mode allows someone to set more or less aggressive approaches to
> reclaim memory when a zone runs out of memory. If it is set to zero then no
> zone reclaim occurs. Allocations will be satisfied from other zones / nodes
> in the system.
>
> This is value ORed together of
>
> 1 = Zone reclaim on
> 2 = Zone reclaim writes dirty pages out
> 4 = Zone reclaim swaps pages
>
>
> So, "(zone_reclaim_mode & RECLAIM_SWAP) == 0" mean we don't want to reclaim
> swap-backed pages. not mapped file.
>
> Thus, may_swap is better than may_unmap.
>
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Christoph Lameter <cl@linux-foundation.org>
> Cc: Rik van Riel <riel@redhat.com>

Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>