Commit 10c66904 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: switch !DRAIN fast path when possible 



->drain_used is one way, which is not optimal if users use DRAIN but
very rarely. However, we can just clear it in io_drain_req() when all
drained before requests are gone. Also rename the flag to reflect the
change and be more clear about it.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7f37a240857546a94df6348507edddacab150460.1623772051.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 27f6b318

fs/io_uring.c

+8 −6
Original line number Diff line number Diff line
@@ -352,7 +352,7 @@ struct io_ring_ctx { 
		unsigned int		eventfd_async: 1;

		unsigned int		restricted: 1;

		unsigned int		off_timeout_used: 1;

		unsigned int		drain_used: 1;

		unsigned int		drain_active: 1;

	} ____cacheline_aligned_in_smp;



	/* submission data */
@@ -1346,10 +1346,10 @@ static void io_flush_timeouts(struct io_ring_ctx *ctx) 


static void io_commit_cqring(struct io_ring_ctx *ctx)

{

	if (unlikely(ctx->off_timeout_used || ctx->drain_used)) {

	if (unlikely(ctx->off_timeout_used || ctx->drain_active)) {

		if (ctx->off_timeout_used)

			io_flush_timeouts(ctx);

		if (ctx->drain_used)

		if (ctx->drain_active)

			io_queue_deferred(ctx);

	}

	/* order cqe stores with ring update */
@@ -6004,8 +6004,10 @@ static bool io_drain_req(struct io_kiocb *req) 


	/* Still need defer if there is pending req in defer list. */

	if (likely(list_empty_careful(&ctx->defer_list) &&

		!(req->flags & REQ_F_IO_DRAIN)))

		!(req->flags & REQ_F_IO_DRAIN))) {

		ctx->drain_active = false;

		return false;

	}



	seq = io_get_sequence(req);

	/* Still a chance to pass the sequence check */
@@ -6446,7 +6448,7 @@ static void __io_queue_sqe(struct io_kiocb *req) 


static inline void io_queue_sqe(struct io_kiocb *req)

{

	if (unlikely(req->ctx->drain_used) && io_drain_req(req))

	if (unlikely(req->ctx->drain_active) && io_drain_req(req))

		return;



	if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) {
@@ -6572,7 +6574,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, 
	}



	if (unlikely(req->flags & REQ_F_IO_DRAIN)) {

		ctx->drain_used = true;

		ctx->drain_active = true;



		/*

		 * Taking sequential execution of a link, draining both sides