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From: Jiufei Xue <[email protected]>
To: [email protected]
Cc: [email protected], [email protected]
Subject: [PATCH v4 2/2] io_uring: use EPOLLEXCLUSIVE flag to aoid thundering herd type behavior
Date: Wed, 17 Jun 2020 17:53:56 +0800	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Applications can pass this flag in to avoid accept thundering herd.

Signed-off-by: Jiufei Xue <[email protected]>
---
 fs/io_uring.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index fe935cf..f156eba 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4225,7 +4225,11 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 
 	pt->error = 0;
 	poll->head = head;
-	add_wait_queue(head, &poll->wait);
+
+	if (poll->events & EPOLLEXCLUSIVE)
+		add_wait_queue_exclusive(head, &poll->wait);
+	else
+		add_wait_queue(head, &poll->wait);
 }
 
 static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
@@ -4556,7 +4560,8 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 #ifdef __BIG_ENDIAN
 	events = swahw32(events);
 #endif
-	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
+	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP |
+		       (events & EPOLLEXCLUSIVE);
 
 	get_task_struct(current);
 	req->task = current;
-- 
1.8.3.1


      parent reply	other threads:[~2020-06-17  9:54 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-17  9:53 [PATCH v4 0/2] io_uring: add EPOLLEXCLUSIVE flag for POLL_ADD operation Jiufei Xue
2020-06-17  9:53 ` [PATCH v4 1/2] io_uring: change the poll type to be 32-bits Jiufei Xue
2020-06-17 15:15   ` Jens Axboe
2020-06-17  9:53 ` Jiufei Xue [this message]

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