[PATCH 5/7] mm: vmscan: Do not writeback filesystem pages in kswapd except in high priority

[KAMEZAWA Hiroyuki]

On Wed, 10 Aug 2011 11:47:18 +0100
Mel Gorman <mgorman at suse.de> wrote:

> It is preferable that no dirty pages are dispatched for cleaning from
> the page reclaim path. At normal priorities, this patch prevents kswapd
> writing pages.
> 
> However, page reclaim does have a requirement that pages be freed
> in a particular zone. If it is failing to make sufficient progress
> (reclaiming < SWAP_CLUSTER_MAX at any priority priority), the priority
> is raised to scan more pages. A priority of DEF_PRIORITY - 3 is
> considered to be the point where kswapd is getting into trouble
> reclaiming pages. If this priority is reached, kswapd will dispatch
> pages for writing.
> 
> Signed-off-by: Mel Gorman <mgorman at suse.de>
> Reviewed-by: Minchan Kim <minchan.kim at gmail.com>


Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>

BTW, I'd like to see summary of the effect of priority..