On Wed, Jul 13, 2011 at 09:42:39AM +0900, KOSAKI Motohiro wrote: > (2011/07/11 22:01), Mel Gorman wrote: > > With zone_reclaim_mode enabled, it's possible for zones to be considered > > full in the zonelist_cache so they are skipped in the future. If the > > process enters direct reclaim, the ZLC may still consider zones to be > > full even after reclaiming pages. Reconsider all zones for allocation > > if direct reclaim returns successfully. > > > > Signed-off-by: Mel Gorman <mgorman@xxxxxxx> > > Hmmm... > > I like the concept, but I'm worry about a corner case a bit. > > If users are using cpusets/mempolicy, direct reclaim don't scan all zones. > Then, zlc_clear_zones_full() seems too aggressive operation. As the system is likely to be running slow if it is in direct reclaim that the complexity of being careful about which zone was cleared was not worth it. > Instead, couldn't we turn zlc->fullzones off from kswapd? > Which zonelist should it clear (there are two) and when should it happen? If it clears it on each cycle around balance_pgdat(), there is no guarantee that it'll be cleared between when direct reclaim finishes and an attempt is made to allocate. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>