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authorPavel Begunkov <asml.silence@gmail.com>2021-10-21 14:30:52 +0100
committerJens Axboe <axboe@kernel.dk>2021-10-21 08:37:26 -0600
commite94f68527a35271131cdf9d3fb4eb3c2513dc3d0 (patch)
tree19e56f1f95fc139c2be23250dbc2b65bc2a33d42 /block
parent3b13c168186c115501ee7d194460ba2f8c825155 (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.c2
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;
/*