On Wed, 27 Jun 2012, Rik van Riel wrote: > > I doubt compaction try to migrate continuously although we have no free > > memory. > > Could you apply this patch and retest? > > > > https://lkml.org/lkml/2012/6/21/30 > Not sure if Jim is using memcg; if not, then this won't be helpful. > Another possibility is that compaction is succeeding every time, > but since we always start scanning all the way at the beginning > and end of each zone, we waste a lot of CPU time rescanning the > same pages (that we just filled up with moved pages) to see if > any are free. > > In short, due to the way compaction behaves right now, > compaction + isolate_freepages are essentially quadratic. > > What we need to do is remember where we left off after a > successful compaction, so we can continue the search there > at the next invocation. > So when the free and migration scanners meet and compact_finished() == COMPACT_CONTINUE, loop around to the start of the zone and continue until you reach the pfn that it was started at? Seems appropriate. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>