From f4805eded7d38c4e42bf473dc5eb2f34853beb06 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 10 Nov 2005 16:53:30 -0800 Subject: [TCP]: fix congestion window update when using TSO deferal TCP peformance with TSO over networks with delay is awful. On a 100Mbit link with 150ms delay, we get 4Mbits/sec with TSO and 50Mbits/sec without TSO. The problem is with TSO, we intentionally do not keep the maximum number of packets in flight to fill the window, we hold out to until we can send a MSS chunk. But, we also don't update the congestion window unless we have filled, as per RFC2861. This patch replaces the check for the congestion window being full with something smarter that accounts for TSO. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- include/net/tcp.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'include/net') diff --git a/include/net/tcp.h b/include/net/tcp.h index 96cc3b434e40..15bdbc6bd571 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -810,6 +810,27 @@ static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) return 3; } +/* RFC2861 Check whether we are limited by application or congestion window + * This is the inverse of cwnd check in tcp_tso_should_defer + */ +static inline int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight) +{ + const struct tcp_sock *tp = tcp_sk(sk); + u32 left; + + if (in_flight >= tp->snd_cwnd) + return 1; + + if (!(sk->sk_route_caps & NETIF_F_TSO)) + return 0; + + left = tp->snd_cwnd - in_flight; + if (sysctl_tcp_tso_win_divisor) + return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd; + else + return left <= tcp_max_burst(tp); +} + static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss, const struct sk_buff *skb) { -- cgit v1.2.2