diff mbox series

[v14,08/11] io_uring/zcrx: throttle receive requests

Message ID 20250215000947.789731-9-dw@davidwei.uk (mailing list archive)
State Handled Elsewhere
Headers show
Series io_uring zero copy rx | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply, async

Commit Message

David Wei Feb. 15, 2025, 12:09 a.m. UTC 
From: Pavel Begunkov <asml.silence@gmail.com>

io_zc_rx_tcp_recvmsg() continues until it fails or there is nothing to
receive. If the other side sends fast enough, we might get stuck in
io_zc_rx_tcp_recvmsg() producing more and more CQEs but not letting the
user to handle them leading to unbound latencies.

Break out of it based on an arbitrarily chosen limit, the upper layer
will either return to userspace or requeue the request.

Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 io_uring/net.c  | 2 ++
 io_uring/zcrx.c | 9 +++++++++
 2 files changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/io_uring/net.c b/io_uring/net.c
index 260eb73a5854..000dc70d08d0 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -1285,6 +1285,8 @@  int io_recvzc(struct io_kiocb *req, unsigned int issue_flags)
 	if (unlikely(ret <= 0) && ret != -EAGAIN) {
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
+		if (ret == IOU_REQUEUE)
+			return IOU_REQUEUE;
 
 		req_set_fail(req);
 		io_req_set_res(req, ret, 0);
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 7d24fc98b306..7e0cba1e0f39 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -94,10 +94,13 @@  static void io_zcrx_sync_for_device(const struct page_pool *pool,
 
 #define IO_RQ_MAX_ENTRIES		32768
 
+#define IO_SKBS_PER_CALL_LIMIT	20
+
 struct io_zcrx_args {
 	struct io_kiocb		*req;
 	struct io_zcrx_ifq	*ifq;
 	struct socket		*sock;
+	unsigned		nr_skbs;
 };
 
 static const struct memory_provider_ops io_uring_pp_zc_ops;
@@ -720,6 +723,9 @@  io_zcrx_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
 	int i, copy, end, off;
 	int ret = 0;
 
+	if (unlikely(args->nr_skbs++ > IO_SKBS_PER_CALL_LIMIT))
+		return -EAGAIN;
+
 	start = skb_headlen(skb);
 	start_off = offset;
 
@@ -810,6 +816,9 @@  static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
 			ret = -ENOTCONN;
 		else
 			ret = -EAGAIN;
+	} else if (unlikely(args.nr_skbs > IO_SKBS_PER_CALL_LIMIT) &&
+		   (issue_flags & IO_URING_F_MULTISHOT)) {
+		ret = IOU_REQUEUE;
 	} else if (sock_flag(sk, SOCK_DONE)) {
 		/* Make it to retry until it finally gets 0. */
 		if (issue_flags & IO_URING_F_MULTISHOT)