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tcp: tcp_vegas ssthresh bugfix

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This patch fixes ssthresh accounting issues in tcp_vegas when cwnd decreases

Signed-off-by: Doug Leith <doug.leith@nuim.ie>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Doug Leith 2009-05-25 22:44:59 -07:00 committed by David S. Miller
parent 217cbfa856
commit c80a5cdfc5
1 changed files with 9 additions and 2 deletions
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11
net/ipv4/tcp_vegas.c
View file

@ -158,6 +158,11 @@ void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event)
} }
EXPORT_SYMBOL_GPL(tcp_vegas_cwnd_event); EXPORT_SYMBOL_GPL(tcp_vegas_cwnd_event);
static inline u32 tcp_vegas_ssthresh(struct tcp_sock *tp)
{
return min(tp->snd_ssthresh, tp->snd_cwnd-1);
}
static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{ {
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
@ -221,11 +226,10 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
*/ */
diff = tp->snd_cwnd * (rtt-vegas->baseRTT) / vegas->baseRTT; diff = tp->snd_cwnd * (rtt-vegas->baseRTT) / vegas->baseRTT;
if (diff > gamma && tp->snd_ssthresh > 2 ) { if (diff > gamma && tp->snd_cwnd <= tp->snd_ssthresh) {
/* Going too fast. Time to slow down /* Going too fast. Time to slow down
* and switch to congestion avoidance. * and switch to congestion avoidance.
*/ */
tp->snd_ssthresh = 2;
/* Set cwnd to match the actual rate /* Set cwnd to match the actual rate
* exactly: * exactly:
@ -235,6 +239,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
* utilization. * utilization.
*/ */
tp->snd_cwnd = min(tp->snd_cwnd, (u32)target_cwnd+1); tp->snd_cwnd = min(tp->snd_cwnd, (u32)target_cwnd+1);
tp->snd_ssthresh = tcp_vegas_ssthresh(tp);
} else if (tp->snd_cwnd <= tp->snd_ssthresh) { } else if (tp->snd_cwnd <= tp->snd_ssthresh) {
/* Slow start. */ /* Slow start. */
@ -250,6 +255,8 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
* we slow down. * we slow down.
*/ */
tp->snd_cwnd--; tp->snd_cwnd--;
tp->snd_ssthresh
= tcp_vegas_ssthresh(tp);
} else if (diff < alpha) { } else if (diff < alpha) {
/* We don't have enough extra packets /* We don't have enough extra packets
* in the network, so speed up. * in the network, so speed up.