io_uring: optimise head checks in io_get_sqring()

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A user may ask to submit more than there is in the ring, and then
io_uring will submit as much as it can. However, in the last iteration
it will allocate an io_kiocb and immediately free it. It could do
better and adjust @to_submit to what is in the ring.

And since the ring's head is already checked here, there is no need to
do it in the loop, spamming with smp_load_acquire()'s barriers

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Pavel Begunkov 2019-12-30 21:24:45 +03:00 • committed by Jens Axboe

parent 9ef4f12489

commit ee7d46d9db

1 changed files with 4 additions and 9 deletions

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fs/io_uring.c

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