Commit 26722873 authored by David S. Miller's avatar David S. Miller
Browse files

[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: default avatarDavid S. Miller <davem@davemloft.net>
parent a96fb49b
...@@ -755,7 +755,15 @@ void tcp_update_metrics(struct sock *sk) ...@@ -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 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst)
{ {
__u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);
......
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