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authorPavel Begunkov <asml.silence@gmail.com>2019-11-29 00:11:53 +0300
committerJens Axboe <axboe@kernel.dk>2019-12-19 06:08:50 -0700
commit7d30a621028a22a9e8fbae5c5d8dc455869e4999 (patch)
tree2ed626e9fce51d89849495a2ab5a8b68496fb4ce /block
parent80a0c2e511a97e11d82e0ec11564e2c3fe624b0d (diff)
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blk-mq: optimise rq sort function
Check "!=" in multi-layer comparisons. The same memory usage, fewer instructions, and 2 from 4 jumps are replaced with SETcc. Note, that list_sort() doesn't differ 0 and <0. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 323c9cb28066..f32a3cfdd34e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1668,14 +1668,10 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
struct request *rqa = container_of(a, struct request, queuelist);
struct request *rqb = container_of(b, struct request, queuelist);
- if (rqa->mq_ctx < rqb->mq_ctx)
- return -1;
- else if (rqa->mq_ctx > rqb->mq_ctx)
- return 1;
- else if (rqa->mq_hctx < rqb->mq_hctx)
- return -1;
- else if (rqa->mq_hctx > rqb->mq_hctx)
- return 1;
+ if (rqa->mq_ctx != rqb->mq_ctx)
+ return rqa->mq_ctx > rqb->mq_ctx;
+ if (rqa->mq_hctx != rqb->mq_hctx)
+ return rqa->mq_hctx > rqb->mq_hctx;
return blk_rq_pos(rqa) > blk_rq_pos(rqb);
}