Re: [PATCH] vmscan: evict use-once pages first (v3)

Johannes Weiner
2009-04-30T08:12:38Z

On Wed, Apr 29, 2009 at 01:14:36PM -0400, Rik van Riel wrote:
> When the file LRU lists are dominated by streaming IO pages,
> evict those pages first, before considering evicting other
> pages.
>
> This should be safe from deadlocks or performance problems
> because only three things can happen to an inactive file page:
> 1) referenced twice and promoted to the active list
> 2) evicted by the pageout code
> 3) under IO, after which it will get evicted or promoted
>
> The pages freed in this way can either be reused for streaming
> IO, or allocated for something else. If the pages are used for
> streaming IO, this pageout pattern continues. Otherwise, we will
> fall back to the normal pageout pattern.
>
> Signed-off-by: Rik van Riel <riel@redhat.com>

Although Elladan didn't test this exact patch, he reported on v2 that
the general idea of scanning active files only when they exceed the
inactive set works.

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