public inbox for [email protected]
 help / color / mirror / Atom feed
From: Xiaoguang Wang <[email protected]>
To: [email protected]
Cc: [email protected], [email protected],
	Xiaoguang Wang <[email protected]>
Subject: [RFC 2/3] io_uring: don't get completion_lock in io_poll_rewait()
Date: Wed, 22 Sep 2021 20:34:16 +0800	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

In current implementation, if there are not available events,
io_poll_rewait() just gets completion_lock, and unlocks it in
io_poll_task_func() or io_async_task_func(), which isn't necessary.

Change this logic to let io_poll_task_func() or io_async_task_func()
get the completion_lock lock, this is also a preparation for
later patch, which will batch poll request completion.

Signed-off-by: Xiaoguang Wang <[email protected]>
---
 fs/io_uring.c | 50 ++++++++++++++++++++++----------------------------
 1 file changed, 22 insertions(+), 28 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ca4464a75c7b..6fdfb688cf91 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5040,10 +5040,7 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
 }
 
 static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
-	__acquires(&req->ctx->completion_lock)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-
 	/* req->task == current here, checking PF_EXITING is safe */
 	if (unlikely(req->task->flags & PF_EXITING))
 		WRITE_ONCE(poll->canceled, true);
@@ -5054,7 +5051,6 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
 		req->result = vfs_poll(req->file, &pt) & poll->events;
 	}
 
-	spin_lock(&ctx->completion_lock);
 	if (!req->result && !READ_ONCE(poll->canceled)) {
 		if (req->opcode == IORING_OP_POLL_ADD)
 			WRITE_ONCE(req->poll.active, true);
@@ -5142,30 +5138,29 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_kiocb *nxt;
+	bool done;
 
-	if (io_poll_rewait(req, &req->poll)) {
-		spin_unlock(&ctx->completion_lock);
-	} else {
-		bool done;
+	if (io_poll_rewait(req, &req->poll))
+		return;
 
-		done = __io_poll_complete(req, req->result);
-		if (done) {
-			io_poll_remove_double(req);
-			__io_poll_remove_one(req, io_poll_get_single(req), true);
-			hash_del(&req->hash_node);
-		} else {
-			req->result = 0;
-			WRITE_ONCE(req->poll.active, true);
-		}
-		io_commit_cqring(ctx);
-		spin_unlock(&ctx->completion_lock);
-		io_cqring_ev_posted(ctx);
+	spin_lock(&ctx->completion_lock);
+	done = __io_poll_complete(req, req->result);
+	if (done) {
+		io_poll_remove_double(req);
+		__io_poll_remove_one(req, io_poll_get_single(req), true);
+		hash_del(&req->hash_node);
+	} else {
+		req->result = 0;
+		WRITE_ONCE(req->poll.active, true);
+	}
+	io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	io_cqring_ev_posted(ctx);
 
-		if (done) {
-			nxt = io_put_req_find_next(req);
-			if (nxt)
-				io_req_task_submit(nxt, locked);
-		}
+	if (done) {
+		nxt = io_put_req_find_next(req);
+		if (nxt)
+			io_req_task_submit(nxt, locked);
 	}
 }
 
@@ -5284,11 +5279,10 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked)
 
 	trace_io_uring_task_run(req->ctx, req, req->opcode, req->user_data);
 
-	if (io_poll_rewait(req, &apoll->poll)) {
-		spin_unlock(&ctx->completion_lock);
+	if (io_poll_rewait(req, &apoll->poll))
 		return;
-	}
 
+	spin_lock(&ctx->completion_lock);
 	hash_del(&req->hash_node);
 	io_poll_remove_double(req);
 	spin_unlock(&ctx->completion_lock);
-- 
2.14.4.44.g2045bb6


  parent reply	other threads:[~2021-09-22 12:34 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 12:34 [RFC 0/3] improvements for poll requests Xiaoguang Wang
2021-09-22 12:34 ` [RFC 1/3] io_uring: reduce frequent add_wait_queue() overhead for multi-shot poll request Xiaoguang Wang
2021-09-22 17:52   ` Hao Xu
2021-09-22 12:34 ` Xiaoguang Wang [this message]
2021-09-22 12:34 ` [RFC 3/3] io_uring: try to batch poll request completion Xiaoguang Wang
2021-09-22 16:24   ` Pavel Begunkov
2021-09-24  4:28     ` Xiaoguang Wang
2021-09-22 17:00   ` Hao Xu
2021-09-22 17:01     ` Hao Xu
2021-09-22 17:09       ` Hao Xu
2021-09-22 13:00 ` [RFC 0/3] improvements for poll requests Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210922123417.2844-3-xiaoguang.wang@linux.alibaba.com \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox