From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, compaction: restrict full priority to non-costly orders The new ultimate compaction priority disables some heuristics, which may result in excessive cost. This is fine for non-costly orders where we want to try hard before resulting for OOM, but might be disruptive for costly orders which do not trigger OOM and should generally have some fallback. Thus, we disable the full priority for costly orders. Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20160906135258.18335-4-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/compaction.h | 1 + mm/page_alloc.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) diff -puN include/linux/compaction.h~mm-compaction-restrict-full-priority-to-non-costly-orders include/linux/compaction.h --- a/include/linux/compaction.h~mm-compaction-restrict-full-priority-to-non-costly-orders +++ a/include/linux/compaction.h @@ -9,6 +9,7 @@ enum compact_priority { COMPACT_PRIO_SYNC_FULL, MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL, COMPACT_PRIO_SYNC_LIGHT, + MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, COMPACT_PRIO_ASYNC, INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC diff -puN mm/page_alloc.c~mm-compaction-restrict-full-priority-to-non-costly-orders mm/page_alloc.c --- a/mm/page_alloc.c~mm-compaction-restrict-full-priority-to-non-costly-orders +++ a/mm/page_alloc.c @@ -3163,6 +3163,7 @@ should_compact_retry(struct alloc_contex int *compaction_retries) { int max_retries = MAX_COMPACT_RETRIES; + int min_priority; if (!order) return false; @@ -3205,7 +3206,9 @@ should_compact_retry(struct alloc_contex * all retries or failed at the lower priorities. */ check_priority: - if (*compact_priority > MIN_COMPACT_PRIORITY) { + min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ? + MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY; + if (*compact_priority > min_priority) { (*compact_priority)--; *compaction_retries = 0; return true; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
