On Tue, Dec 09, 2014 at 12:09:40PM +0900, Minchan Kim wrote: > On Thu, Dec 04, 2014 at 06:12:57PM +0100, Vlastimil Babka wrote: > > When allocation falls back to stealing free pages of another migratetype, > > it can decide to steal extra pages, or even the whole pageblock in order to > > reduce fragmentation, which could happen if further allocation fallbacks > > pick a different pageblock. In try_to_steal_freepages(), one of the > > situations > > where extra pages are stolen happens when we are trying to allocate a > > MIGRATE_RECLAIMABLE page. > > > > However, MIGRATE_UNMOVABLE allocations are not treated the same way, > > although > > spreading such allocation over multiple fallback pageblocks is arguably even > > worse than it is for RECLAIMABLE allocations. To minimize fragmentation, we > > should minimize the number of such fallbacks, and thus steal as much as is > > possible from each fallback pageblock. > > Fair enough. >
Just to be absolutly sure, check that data and see what the number of MIGRATE_UNMOVABLE blocks looks like over time. Make sure it's not just continually growing. MIGRATE_RECLAIMABLE and MIGRATE_MOVABLE blocks were expected to be freed if the system was aggressively reclaimed but the same is not be true of MIGRATE_UNMOVABLE. Even if all processes are aggressively reclaimed for example, the page tables are still there. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
