From 26722873a460703e319462afa7ebb8ed3a036c07 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 24 Aug 2007 22:21:50 -0700 Subject: [PATCH] [TCP]: Describe tcp_init_cwnd() thoroughly in a comment. People often get tripped up by this function and think that it does not implemented the prescribed algorithms from RFC2414 and RFC3390, even though it does. So add a comment to head off such misunderstandings in the future. Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f030435e0eb4..9785df37a65f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -755,7 +755,15 @@ void tcp_update_metrics(struct sock *sk) } } -/* Numbers are taken from RFC2414. */ +/* Numbers are taken from RFC3390. + * + * John Heffner states: + * + * The RFC specifies a window of no more than 4380 bytes + * unless 2*MSS > 4380. Reading the pseudocode in the RFC + * is a bit misleading because they use a clamp at 4380 bytes + * rather than use a multiplier in the relevant range. + */ __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst) { __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); -- GitLab