Commit 69629809 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: restructure submit sqes to_submit checks 



Put an explicit check for number of requests to submit. First,
we can turn while into do-while and it generates better code, and second
that if can be cheaper, e.g. by using CPU flags after sub in
io_sqring_entries().

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5926baadd20c28feab7a5e1725fedf32e4553ff7.1632516769.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d9f9d284

fs/io_uring.c

+6 −3
Original line number Diff line number Diff line
@@ -7225,16 +7225,19 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx) 
static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)

	__must_hold(&ctx->uring_lock)

{

	unsigned int entries = io_sqring_entries(ctx);

	int submitted = 0;



	if (!entries)

		return 0;

	/* make sure SQ entry isn't read before tail */

	nr = min3(nr, ctx->sq_entries, io_sqring_entries(ctx));

	nr = min3(nr, ctx->sq_entries, entries);

	if (!percpu_ref_tryget_many(&ctx->refs, nr))

		return -EAGAIN;

	io_get_task_refs(nr);



	io_submit_state_start(&ctx->submit_state, nr);

	while (submitted < nr) {

	do {

		const struct io_uring_sqe *sqe;

		struct io_kiocb *req;
@@ -7253,7 +7256,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) 
		submitted++;

		if (io_submit_sqe(ctx, req, sqe))

			break;

	}

	} while (submitted < nr);



	if (unlikely(submitted != nr)) {

		int ref_used = (submitted == -EAGAIN) ? 0 : submitted;