diff options
| author | Pavel Begunkov <asml.silence@gmail.com> | 2021-10-21 14:30:52 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-21 08:37:26 -0600 |
| commit | e94f68527a35271131cdf9d3fb4eb3c2513dc3d0 (patch) | |
| tree | 19e56f1f95fc139c2be23250dbc2b65bc2a33d42 /block | |
| parent | 3b13c168186c115501ee7d194460ba2f8c825155 (diff) | |
block: kill extra rcu lock/unlock in queue enter
blk_try_enter_queue() already takes rcu_read_lock/unlock, so we can
avoid the second pair in percpu_ref_tryget_live(), use a newly added
percpu_ref_tryget_live_rcu().
As rcu_read_lock/unlock imply barrier()s, it's pretty noticeable,
especially for for !CONFIG_PREEMPT_RCU (default for some distributions),
where __rcu_read_lock/unlock() are not inlined.
3.20% io_uring [kernel.vmlinux] [k] __rcu_read_unlock
3.05% io_uring [kernel.vmlinux] [k] __rcu_read_lock
2.52% io_uring [kernel.vmlinux] [k] __rcu_read_unlock
2.28% io_uring [kernel.vmlinux] [k] __rcu_read_lock
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6b11c67ea495ed9d44f067622d852de4a510ce65.1634822969.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index dfa199312c2f..fd389a16013c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -389,7 +389,7 @@ EXPORT_SYMBOL(blk_cleanup_queue); static bool blk_try_enter_queue(struct request_queue *q, bool pm) { rcu_read_lock(); - if (!percpu_ref_tryget_live(&q->q_usage_counter)) + if (!percpu_ref_tryget_live_rcu(&q->q_usage_counter)) goto fail; /* |