On Fri, 10 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> > Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Started reviewing before I saw this series. Reviewed-by: Eric B Munson <emunson@xxxxxxxxx>
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