On 10/07/2014 11:33 AM, Vlastimil Babka wrote:
Deferred compaction is employed to avoid compacting zone where sync direct compaction has recently failed. As such, it makes sense to only defer when a full zone was scanned, which is when compact_zone returns with COMPACT_COMPLETE. It's less useful to defer when compact_zone returns with apparent success (COMPACT_PARTIAL), followed by a watermark check failure, which can happen due to parallel allocation activity. It also does not make much sense to defer compaction which was completely skipped (COMPACT_SKIP) for being unsuitable in the first place. This patch therefore makes deferred compaction trigger only when COMPACT_COMPLETE is returned from compact_zone(). Results of stress-highalloc becnmark show the difference is within measurement error, so the issue is rather cosmetic. Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx> -- 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>