Re: [PATCH 1/6] mm: kswapd: Stop high-order balancing when anysuitable zone is balanced

[Eric B Munson]

On Thu, 09 Dec 2010, Mel Gorman wrote:

> When the allocator enters its slow path, kswapd is woken up to balance the
> node. It continues working until all zones within the node are balanced. For
> order-0 allocations, this makes perfect sense but for higher orders it can
> have unintended side-effects. If the zone sizes are imbalanced, kswapd may
> reclaim heavily within a smaller zone discarding an excessive number of
> pages. The user-visible behaviour is that kswapd is awake and reclaiming
> even though plenty of pages are free from a suitable zone.
> 
> This patch alters the "balance" logic for high-order reclaim allowing kswapd
> to stop if any suitable zone becomes balanced to reduce the number of pages
> it reclaims from other zones. kswapd still tries to ensure that order-0
> watermarks for all zones are met before sleeping.
> 
> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>

Looks good to me.

Reviewed-by: Eric B Munson <emunson@xxxxxxxxx>

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