bpf: Adds support for setting initial cwnd (fc747810) · Commits · 戴 / test

Adds a new bpf_setsockopt for TCP sockets, TCP_BPF_IW, which sets the initial congestion window. This can be used when the hosts are far apart (large RTTs) and it is safe to start with a large inital cwnd. Signed-off-by:

Lawrence Brakmo <brakmo@fb.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/uapi/linux/bpf.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -783,4 +783,6 @@ enum {
		*/
		};

		#define TCP_BPF_IW 1001 /* Set TCP initial congestion window */

		#endif /* _UAPI__LINUX_BPF_H__ */

net/core/filter.c

+17 −1

Original line number	Diff line number	Diff line
		@@ -2732,7 +2732,23 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
		tcp_reinit_congestion_control(sk,
		inet_csk(sk)->icsk_ca_ops);
		} else {
		struct tcp_sock *tp = tcp_sk(sk);

		if (optlen != sizeof(int))
		return -EINVAL;

		val = ((int )optval);
		/* Only some options are supported */
		switch (optname) {
		case TCP_BPF_IW:
		if (val <= 0 \|\| tp->data_segs_out > 0)
		ret = -EINVAL;
		else
		tp->snd_cwnd = val;
		break;
		default:
		ret = -EINVAL;
		}
		}
		#else
		ret = -EINVAL;

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