From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, page_alloc: use unlikely() in task_capc() Hugh noted that task_capc() could use unlikely(), as most of the time there is no capture in progress and we are in page freeing hot path. Indeed adding unlikely() produces assembly that better matches the assumption and moves all the tests away from the hot path. I have also noticed that we don't need to test for cc->direct_compaction as the only place we set current->task_capture is compact_zone_order() which also always sets cc->direct_compaction true. Link: http://lkml.kernel.org/r/4a24f7af-3aa5-6e80-4ae6-8f253b562039@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx> Acked-by: Hugh Dickins <hughd@googlecom> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> Cc: Li Wang <liwang@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-use-unlikely-in-task_capc +++ a/mm/page_alloc.c @@ -813,11 +813,10 @@ static inline struct capture_control *ta { struct capture_control *capc = current->capture_control; - return capc && + return unlikely(capc) && !(current->flags & PF_KTHREAD) && !capc->page && - capc->cc->zone == zone && - capc->cc->direct_compaction ? capc : NULL; + capc->cc->zone == zone ? capc : NULL; } static inline bool _
