diff mbox series

[RFC,v2,13/13] io_uring: add io_req_local_work_add wake fast path

Message ID f7c52527313e6f0d8dff2bb36ecad2380f5c5c9c.1672713341.git.asml.silence@gmail.com (mailing list archive)
State New
Headers show
Series CQ waiting and wake up optimisations | expand

Commit Message

Pavel Begunkov Jan. 3, 2023, 3:04 a.m. UTC 
Don't wake the master task after queueing a deferred tw unless it's
currently waiting in io_cqring_wait.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/io_uring_types.h | 1 +
 io_uring/io_uring.c            | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 1452ff745e5c..332a29cfe076 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -285,6 +285,7 @@  struct io_ring_ctx {
 
 		unsigned		cached_cq_tail;
 		unsigned		cq_entries;
+		bool			cq_waiting;
 		struct io_ev_fd	__rcu	*io_ev_fd;
 		struct wait_queue_head	cq_wait;
 		struct wait_queue_head	poll_wq;
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 943032d2fd21..e436fe73becf 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1275,7 +1275,8 @@  static void io_req_local_work_add(struct io_kiocb *req)
 		io_eventfd_signal(ctx);
 
 	if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
-		wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
+		if (READ_ONCE(ctx->cq_waiting))
+			wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
 	} else {
 		__io_cqring_wake(ctx);
 	}
@@ -2565,6 +2566,7 @@  static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 
 		if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
 			set_current_state(TASK_INTERRUPTIBLE);
+			smp_store_mb(ctx->cq_waiting, 1);
 		} else {
 			prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
 							TASK_INTERRUPTIBLE);
@@ -2572,6 +2574,8 @@  static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 
 		ret = io_cqring_wait_schedule(ctx, &iowq, timeout);
 		__set_current_state(TASK_RUNNING);
+		WRITE_ONCE(ctx->cq_waiting, 0);
+
 		if (ret < 0)
 			break;
 		/*