Commit 76d727ae authored by Feng Yang's avatar Feng Yang Committed by Jakub Kicinski
Browse files

skbuff: Add MSG_MORE flag to optimize tcp large packet transmission 



When using sockmap for forwarding, the average latency for different packet sizes
after sending 10,000 packets is as follows:
size    old(us)         new(us)
512     56              55
1472    58              58
1600    106             81
3000    145             105
5000    182             125

Suggested-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarFeng Yang <yangfeng@kylinos.cn>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250708054053.39551-1-yangfeng59949@163.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent fb604576

net/core/skbuff.c

+5 −0
Original line number Diff line number Diff line
@@ -3230,6 +3230,7 @@ typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg); 
static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,

			   int len, sendmsg_func sendmsg, int flags)

{

	int more_hint = sk_is_tcp(sk) ? MSG_MORE : 0;

	unsigned int orig_len = len;

	struct sk_buff *head = skb;

	unsigned short fragidx;
@@ -3247,6 +3248,8 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, 
		kv.iov_len = slen;

		memset(&msg, 0, sizeof(msg));

		msg.msg_flags = MSG_DONTWAIT | flags;

		if (slen < len)

			msg.msg_flags |= more_hint;



		iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);

		ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
@@ -3287,6 +3290,8 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, 
					     flags,

			};



			if (slen < len)

				msg.msg_flags |= more_hint;

			bvec_set_page(&bvec, skb_frag_page(frag), slen,

				      skb_frag_off(frag) + offset);

			iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,