diff options
| author | Wen Xiong <wenxiong@linux.ibm.com> | 2026-06-16 10:31:21 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-06-16 10:06:27 -0600 |
| commit | 9cbbac29d752fb5d95e375fa3685a359b89caa0a (patch) | |
| tree | 136736d757628eeca8f6ea08ffb37989b6ec9c91 | |
| parent | 4f919141be38ea2b1314e3a531b7b998eb64e8bc (diff) | |
block: Remove redundant plug in __submit_bio()
The patch removes the automatic plug/unplug operations from __submit_bio()
that were added to cache nsecs time when no explicit plug is used.
The plug mechanism is most effective when batching multiple I/O
operations together. Creating a plug for every bio submission
provides minimal benefit while adding function call overhead and
stack usage for every I/O operation.
Below is performance comparison with the latest upstream kernel.
Iotype qd nj rmix mpstat busy mpstat busy without plug
Randrw 1 20 100 53% 24%
Randrw 1 40 100 70% 24%
Randrw 1 20 70 40% 24%
Randrw 1 40 70 60% 26%
Randrw 1 20 0 14% 6%
Randrw 1 40 0 20% 7%
Fixes: 060406c61c7c ("block: add plug while submitting IO")
Signed-off-by: Wen Xiong <wenxiong@linux.ibm.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260616143121.878021-1-wenxiong@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-core.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 73a41df98c9a..365641266c9e 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -669,11 +669,6 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q, static void __submit_bio(struct bio *bio) { - /* If plug is not used, add new plug here to cache nsecs time. */ - struct blk_plug plug; - - blk_start_plug(&plug); - if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { blk_mq_submit_bio(bio); } else if (likely(bio_queue_enter(bio) == 0)) { @@ -686,8 +681,6 @@ static void __submit_bio(struct bio *bio) disk->fops->submit_bio(bio); blk_queue_exit(disk->queue); } - - blk_finish_plug(&plug); } /* |