Re: [PATCH] vmscan,tmpfs: treat used once pages on tmpfs as usedonce

[Rik van Riel]

On 08/31/2010 09:37 PM, KOSAKI Motohiro wrote:
> When a page has PG_referenced, shrink_page_list() discard it only
> if it is no dirty. This rule works completely fine if the backend
> filesystem is regular one. PG_dirty is good signal that it was used
> recently because flusher thread clean pages periodically. In addition,
> page writeback is costly rather than simple page discard.
>
> However, When a page is on tmpfs, this heuristic don't works because
> flusher thread don't writeback tmpfs pages. then, tmpfs pages always
> rotate lru twice at least and it makes unnecessary lru churn. Merely
> tmpfs streaming io shouldn't cause large anonymous page swap-out.
>
> This patch remove this unncessary reclaim bonus of tmpfs pages.
>
> Cc: Hugh Dickins<hughd@xxxxxxxxxx>
> Cc: Johannes Weiner<hannes@xxxxxxxxxxx>
> Cc: Rik van Riel<riel@xxxxxxxxxx>
> Signed-off-by: KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxxxxxxx>

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

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