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io_uring: move finish_wait() outside of loop in cqring_wait()

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We don't need to call this for every loop. This is particularly
troublesome if we are task_work intensive, and get woken more often than
we desire due to that.

Just do it at the end, that's always safe as we initialize the waitqueue
list head anyway. This can save a considerable amount of hammering on
the waitqueue lock, which is also hot from the request completion side.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-03-25 16:39:57 -06:00
parent 775a1f2f99
commit b4f20bb4e6
1 changed files with 1 additions and 1 deletions
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2
fs/io_uring.c
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@ -8174,10 +8174,10 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
TASK_INTERRUPTIBLE);
ret = io_cqring_wait_schedule(ctx, &iowq, timeout);
finish_wait(&ctx->cq_wait, &iowq.wq);
cond_resched();
} while (ret > 0);
finish_wait(&ctx->cq_wait, &iowq.wq);
restore_saved_sigmask_unless(ret == -EINTR);
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;