linux-kernel - [PATCH 02/15] io_uring: always plug for any number of IOs

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Date:   Thu, 18 Jun 2020 08:43:42 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     io-uring@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 02/15] io_uring: always plug for any number of IOs

Currently we only plug if we're doing more than two request. We're going
to be relying on always having the plug there to pass down information,
so plug unconditionally.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
 fs/io_uring.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b14a8e6a0e15..ca78dd7c79da 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -676,7 +676,6 @@ struct io_kiocb {
 	};
 };
 
-#define IO_PLUG_THRESHOLD		2
 #define IO_IOPOLL_BATCH			8
 
 struct io_submit_state {
@@ -5914,7 +5913,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			  struct file *ring_file, int ring_fd)
 {
-	struct io_submit_state state, *statep = NULL;
+	struct io_submit_state state;
 	struct io_kiocb *link = NULL;
 	int i, submitted = 0;
 
@@ -5931,10 +5930,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 	if (!percpu_ref_tryget_many(&ctx->refs, nr))
 		return -EAGAIN;
 
-	if (nr > IO_PLUG_THRESHOLD) {
-		io_submit_state_start(&state, nr);
-		statep = &state;
-	}
+	io_submit_state_start(&state, nr);
 
 	ctx->ring_fd = ring_fd;
 	ctx->ring_file = ring_file;
@@ -5949,14 +5945,14 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			io_consume_sqe(ctx);
 			break;
 		}
-		req = io_alloc_req(ctx, statep);
+		req = io_alloc_req(ctx, &state);
 		if (unlikely(!req)) {
 			if (!submitted)
 				submitted = -EAGAIN;
 			break;
 		}
 
-		err = io_init_req(ctx, req, sqe, statep);
+		err = io_init_req(ctx, req, sqe, &state);
 		io_consume_sqe(ctx);
 		/* will complete beyond this point, count as submitted */
 		submitted++;
@@ -5982,8 +5978,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 	}
 	if (link)
 		io_queue_link_head(link);
-	if (statep)
-		io_submit_state_end(&state);
+	io_submit_state_end(&state);
 
 	 /* Commit SQ ring head once we've consumed and submitted all SQEs */
 	io_commit_sqring(ctx);
-- 
2.27.0