Re: [PATCH 7/8] writeback: sync old inodes first in background writeback

Rik van Riel
2010-07-19T18:44:16Z

On 07/19/2010 09:11 AM, Mel Gorman wrote:
> From: Wu Fengguang<fengguang.wu@intel.com>
>
> A background flush work may run for ever. So it's reasonable for it to
> mimic the kupdate behavior of syncing old/expired inodes first.
>
> This behavior also makes sense from the perspective of page reclaim.
> File pages are added to the inactive list and promoted if referenced
> after one recycling. If not referenced, it's very easy for pages to be
> cleaned from reclaim context which is inefficient in terms of IO. If
> background flush is cleaning pages, it's best it cleans old pages to
> help minimise IO from reclaim.
>
> Signed-off-by: Wu Fengguang<fengguang.wu@intel.com>
> Signed-off-by: Mel Gorman<mel@csn.ul.ie>

Acked-by: Rik van Riel <riel@redhat.com>

It can probably be optimized, but we really need something
like this...