From 13bfa6f15d0b39254937076ab0557da6875bb455 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Mon, 27 Mar 2023 16:38:14 +0100 Subject: [PATCH] io_uring: remove extra tw trylocks 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 Link: https://lore.kernel.org/r/1ecec9483d58696e248d1bfd52cf62b04442df1d.1679931367.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 24be499..2669aca 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -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++; -- 2.7.4