diff options
| -rw-r--r-- | net/ipv4/tcp_cong.c | 40 |
1 files changed, 22 insertions, 18 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 86b26539e54..1260e52ad77 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -276,30 +276,34 @@ int tcp_set_congestion_control(struct sock *sk, const char *name) /* - * Slow start (exponential increase) with - * RFC3742 Limited Slow Start (fast linear increase) support. + * Slow start is used when congestion window is less than slow start + * threshold. This version implements the basic RFC2581 version + * and optionally supports: + * RFC3742 Limited Slow Start - growth limited to max_ssthresh + * RFC3465 Appropriate Byte Counting - growth limited by bytes acknowledged */ void tcp_slow_start(struct tcp_sock *tp) { - int cnt = 0; - - if (sysctl_tcp_abc) { - /* RFC3465: Slow Start - * TCP sender SHOULD increase cwnd by the number of - * previously unacknowledged bytes ACKed by each incoming - * acknowledgment, provided the increase is not more than L - */ - if (tp->bytes_acked < tp->mss_cache) - return; - } + int cnt; /* increase in packets */ + + /* RFC3465: ABC Slow start + * Increase only after a full MSS of bytes is acked + * + * TCP sender SHOULD increase cwnd by the number of + * previously unacknowledged bytes ACKed by each incoming + * acknowledgment, provided the increase is not more than L + */ + if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache) + return; - if (sysctl_tcp_max_ssthresh > 0 && - tp->snd_cwnd > sysctl_tcp_max_ssthresh) - cnt += sysctl_tcp_max_ssthresh>>1; + if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh) + cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */ else - cnt += tp->snd_cwnd; + cnt = tp->snd_cwnd; /* exponential increase */ - /* RFC3465: We MAY increase by 2 if discovered delayed ack */ + /* RFC3465: ABC + * We MAY increase by 2 if discovered delayed ack + */ if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) cnt <<= 1; tp->bytes_acked = 0; |