From 62748f32d501f5d3712a7c372bbb92abc7c62bc7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 24 Sep 2013 08:20:52 -0700 Subject: net: introduce SO_MAX_PACING_RATE As mentioned in commit afe4fd062416b ("pkt_sched: fq: Fair Queue packet scheduler"), this patch adds a new socket option. SO_MAX_PACING_RATE offers the application the ability to cap the rate computed by transport layer. Value is in bytes per second. u32 val = 1000000; setsockopt(sockfd, SOL_SOCKET, SO_MAX_PACING_RATE, &val, sizeof(val)); To be effectively paced, a flow must use FQ packet scheduler. Note that a packet scheduler takes into account the headers for its computations. The effective payload rate depends on MSS and retransmits if any. I chose to make this pacing rate a SOL_SOCKET option instead of a TCP one because this can be used by other protocols. Signed-off-by: Eric Dumazet Cc: Steinar H. Gunderson Cc: Michael Kerrisk Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5d083855c111..66aa816ad30b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -735,7 +735,7 @@ static void tcp_update_pacing_rate(struct sock *sk) if (tp->srtt > 8 + 2) do_div(rate, tp->srtt); - sk->sk_pacing_rate = min_t(u64, rate, ~0U); + sk->sk_pacing_rate = min_t(u64, rate, sk->sk_max_pacing_rate); } /* Calculate rto without backoff. This is the second half of Van Jacobson's -- cgit v1.2.3-55-g7522