[PATCH RFC for-next 8/8] io_uring: trace task_work_run

[Dylan Yudaken <dylany@fb.com>]

trace task_work_run to help provide stats on how often task work is run
and what batch sizes are coming through.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 io_uring/io_uring.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 0b4d3eb06d16..8cf868315008 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -987,10 +987,12 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
 }
 
 
-static void handle_tw_list(struct llist_node *node,
-			   struct io_ring_ctx **ctx, bool *locked,
-			   struct llist_node *fake)
+static unsigned int handle_tw_list(struct llist_node *node,
+				   struct io_ring_ctx **ctx, bool *locked,
+				   struct llist_node *fake)
 {
+	unsigned int count = 0;
+
 	while (node && node != fake) {
 		struct llist_node *next = node->next;
 		struct io_kiocb *req = container_of(node, struct io_kiocb,
@@ -1051,12 +1053,14 @@ void tctx_task_work(struct callback_head *cb)
 						  task_work);
 	struct llist_node fake = {};
 	struct llist_node *node = io_llist_xchg(&tctx->task_list, &fake);
+	unsigned int loops = 1;
+	unsigned int count = handle_tw_list(node, &ctx, &uring_locked, &fake);
 
-	handle_tw_list(node, &ctx, &uring_locked, &fake);
 	node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);
 	while (node != &fake) {
+		loops++;
 		node = io_llist_xchg(&tctx->task_list, &fake);
-		handle_tw_list(node, &ctx, &uring_locked, &fake);
+		count += handle_tw_list(node, &ctx, &uring_locked, &fake);
 		node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);
 	}
 
@@ -1065,6 +1069,8 @@ void tctx_task_work(struct callback_head *cb)
 	/* relaxed read is enough as only the task itself sets ->in_idle */
 	if (unlikely(atomic_read(&tctx->in_idle)))
 		io_uring_drop_tctx_refs(current);
+
+	trace_io_uring_task_work_run(tctx, count, loops);
 }
 
 void io_req_task_work_add(struct io_kiocb *req)
-- 
2.30.2