From 0864fe09ab90ab32b7d21fe3cd72df5b5af8492e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 20 Dec 2017 13:14:42 -0700 Subject: null_blk: unalign call_single_data Commit 966a967116e6 randomly added alignment to this structure, but it's actually detrimental to performance of null_blk. Test case: Running on both the home and remote node shows a ~5% degradation in performance. While in there, move blk_status_t to the hole after the integer tag in the nullb_cmd structure. After this patch, we shrink the size from 192 to 152 bytes. Fixes: 966a967116e69 ("smp: Avoid using two cache lines for struct call_single_data") Signed-off-by: Jens Axboe --- drivers/block/null_blk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/block/null_blk.c') diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c index ccb9975a97fa..ad0477ae820f 100644 --- a/drivers/block/null_blk.c +++ b/drivers/block/null_blk.c @@ -35,13 +35,13 @@ static inline u64 mb_per_tick(int mbps) struct nullb_cmd { struct list_head list; struct llist_node ll_list; - call_single_data_t csd; + struct __call_single_data csd; struct request *rq; struct bio *bio; unsigned int tag; + blk_status_t error; struct nullb_queue *nq; struct hrtimer timer; - blk_status_t error; }; struct nullb_queue { -- cgit v1.2.3-59-g8ed1b