Re: [PATCH] vmscan: recalculate lru_pages on each priority

From: Johannes Weiner
Date: Sun Jun 27 2010 - 07:34:48 EST

On Fri, Jun 25, 2010 at 06:13:20PM +0900, KOSAKI Motohiro wrote:
> shrink_zones() need relatively long time. and lru_pages can be
> changed dramatically while shrink_zones().
> then, lru_pages need recalculate on each priority.

In the direct reclaim path, we bail out of that loop after
SWAP_CLUSTER_MAX reclaimed pages, so in this case, decreasing priority
levels actually mean we do _not_ make any progress and the total
number of lru pages should not change (much). The possible distortion
in shrink_slab() is small.

However, for the suspend-to-disk case the reclaim target can be a lot
higher and we inevitably end up at higher priorities even though we
make progress, but fail to increase pressure on the shrinkers as well
without your patch.

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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