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io_uring: remove extra tw trylocks

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Before cond_resched()'ing in handle_tw_list() we also drop the current
ring context, and so the next loop iteration will need to pick/pin a new
context and do trylock.

The chunk removed by this patch was intended to be an optimisation
covering exactly this case, i.e. retaking the lock after reschedule, but
in reality it's skipped for the first iteration after resched as
described and will keep hammering the lock if it's contended.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1ecec9483d58696e248d1bfd52cf62b04442df1d.1679931367.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-03-27 16:38:14 +01:00 committed by Jens Axboe
parent 07d99096e1
commit 13bfa6f15d
1 changed files with 1 additions and 2 deletions
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3
io_uring/io_uring.c
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@ -1186,8 +1186,7 @@ static unsigned int handle_tw_list(struct llist_node *node,
/* if not contended, grab and improve batching */
*locked = mutex_trylock(&(*ctx)->uring_lock);
percpu_ref_get(&(*ctx)->refs);
} else if (!*locked)
*locked = mutex_trylock(&(*ctx)->uring_lock);
}
req->io_task_work.func(req, locked);
node = next;
count++;