From: Stephen Hemminger Date: Fri, 11 Nov 2005 00:53:30 +0000 (-0800) Subject: [TCP]: fix congestion window update when using TSO deferal X-Git-Tag: v2.6.15-rc1~20^2~6 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f4805eded7d38c4e42bf473dc5eb2f34853beb06;p=linux-2.6 [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 --- diff --git a/include/net/tcp.h b/include/net/tcp.h index 96cc3b434e..15bdbc6bd5 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) { diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c index ae35e06090..5af99b3ef5 100644 --- a/net/ipv4/tcp_bic.c +++ b/net/ipv4/tcp_bic.c @@ -217,7 +217,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, bictcp_low_utilization(sk, data_acked); - if (in_flight < tp->snd_cwnd) + if (!tcp_is_cwnd_limited(sk, in_flight)) return; if (tp->snd_cwnd <= tp->snd_ssthresh) { diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index bbf2d6624e..0705b496c6 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -186,7 +186,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, { struct tcp_sock *tp = tcp_sk(sk); - if (in_flight < tp->snd_cwnd) + if (!tcp_is_cwnd_limited(sk, in_flight)) return; if (tp->snd_cwnd <= tp->snd_ssthresh) { diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c index 6acc04bde0..5e56ad368d 100644 --- a/net/ipv4/tcp_highspeed.c +++ b/net/ipv4/tcp_highspeed.c @@ -111,12 +111,12 @@ static void hstcp_init(struct sock *sk) } static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt, - u32 in_flight, int good) + u32 in_flight, u32 pkts_acked) { struct tcp_sock *tp = tcp_sk(sk); struct hstcp *ca = inet_csk_ca(sk); - if (in_flight < tp->snd_cwnd) + if (!tcp_is_cwnd_limited(sk, in_flight)) return; if (tp->snd_cwnd <= tp->snd_ssthresh) { diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c index e47b37984e..404a326ba3 100644 --- a/net/ipv4/tcp_htcp.c +++ b/net/ipv4/tcp_htcp.c @@ -207,7 +207,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, struct tcp_sock *tp = tcp_sk(sk); struct htcp *ca = inet_csk_ca(sk); - if (in_flight < tp->snd_cwnd) + if (!tcp_is_cwnd_limited(sk, in_flight)) return; if (tp->snd_cwnd <= tp->snd_ssthresh) { diff --git a/net/ipv4/tcp_hybla.c b/net/ipv4/tcp_hybla.c index 77add63623..40dbb38775 100644 --- a/net/ipv4/tcp_hybla.c +++ b/net/ipv4/tcp_hybla.c @@ -100,12 +100,12 @@ static void hybla_cong_avoid(struct sock *sk, u32 ack, u32 rtt, ca->minrtt = tp->srtt; } + if (!tcp_is_cwnd_limited(sk, in_flight)) + return; + if (!ca->hybla_en) return tcp_reno_cong_avoid(sk, ack, rtt, in_flight, flag); - if (in_flight < tp->snd_cwnd) - return; - if (ca->rho == 0) hybla_recalc_param(sk); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b907456a79..998f6416ef 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2058,3 +2058,4 @@ EXPORT_SYMBOL(tcp_connect); EXPORT_SYMBOL(tcp_make_synack); EXPORT_SYMBOL(tcp_simple_retransmit); EXPORT_SYMBOL(tcp_sync_mss); +EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor); diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c index 327770bf55..a2fd25617d 100644 --- a/net/ipv4/tcp_scalable.c +++ b/net/ipv4/tcp_scalable.c @@ -20,7 +20,8 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, int flag) { struct tcp_sock *tp = tcp_sk(sk); - if (in_flight < tp->snd_cwnd) + + if (!tcp_is_cwnd_limited(sk, in_flight)) return; if (tp->snd_cwnd <= tp->snd_ssthresh) {