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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 5/5] io_uring: limit {io|sq}poll submit locking scope
Date: Thu, 17 Dec 2020 00:24:39 +0000	[thread overview]
Message-ID: <b6ca9998691af60c816ca816f7ddae886f781a3b.1608164394.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

We don't need to take uring_lock for SQPOLL|IOPOLL to do
io_cqring_overflow_flush() when cq_overflow_list is empty, remove it
from the hot path.

Signed-off-by: Pavel Begunkov <[email protected]>
---
 fs/io_uring.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ce580678b8ed..fdb7271127c9 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9162,10 +9162,13 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	 */
 	ret = 0;
 	if (ctx->flags & IORING_SETUP_SQPOLL) {
-		io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
-		if (!list_empty_careful(&ctx->cq_overflow_list))
+		if (!list_empty_careful(&ctx->cq_overflow_list)) {
+			bool needs_lock = ctx->flags & IORING_SETUP_IOPOLL;
+
+			io_ring_submit_lock(ctx, needs_lock);
 			io_cqring_overflow_flush(ctx, false, NULL, NULL);
-		io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
+			io_ring_submit_unlock(ctx, needs_lock);
+		}
 		if (flags & IORING_ENTER_SQ_WAKEUP)
 			wake_up(&ctx->sq_data->wait);
 		if (flags & IORING_ENTER_SQ_WAIT)
-- 
2.24.0


  parent reply	other threads:[~2020-12-17  0:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-17  0:24 [PATCH 0/5] fixes around request overflows Pavel Begunkov
2020-12-17  0:24 ` [PATCH 1/5] io_uring: cancel reqs shouldn't kill overflow list Pavel Begunkov
2020-12-17  0:24 ` [PATCH 2/5] io_uring: remove racy overflow list fast checks Pavel Begunkov
2020-12-17  0:24 ` [PATCH 3/5] io_uring: consolidate CQ nr events calculation Pavel Begunkov
2020-12-17  0:24 ` [PATCH 4/5] io_uring: inline io_cqring_mark_overflow() Pavel Begunkov
2020-12-17  0:24 ` Pavel Begunkov [this message]
2020-12-17  2:26 ` [PATCH 0/5] fixes around request overflows Jens Axboe
2020-12-17  2:38   ` Pavel Begunkov
2020-12-17 15:21     ` Jens Axboe

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