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 --- net/ipv4/tcp_cong.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_cong.c') diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index bbf2d6624e89..0705b496c6b3 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) { -- cgit v1.2.2 From 7faffa1c7fb9b8e8917e3225d4e2638270c0a48b Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 10 Nov 2005 17:07:24 -0800 Subject: [TCP]: add tcp_slow_start helper Move all the code that does linear TCP slowstart to one inline function to ease later patch to add ABC support. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_cong.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'net/ipv4/tcp_cong.c') diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 0705b496c6b3..6d3e883b48f6 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -189,12 +189,11 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, if (!tcp_is_cwnd_limited(sk, in_flight)) return; - if (tp->snd_cwnd <= tp->snd_ssthresh) { - /* In "safe" area, increase. */ - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - } else { - /* In dangerous area, increase slowly. + /* In "safe" area, increase. */ + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + else { + /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */ if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { -- cgit v1.2.2 From 9772efb970780aeed488c19d8b4afd46c3b484af Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 10 Nov 2005 17:09:53 -0800 Subject: [TCP]: Appropriate Byte Count support This is an updated version of the RFC3465 ABC patch originally for Linux 2.6.11-rc4 by Yee-Ting Li. ABC is a way of counting bytes ack'd rather than packets when updating congestion control. The orignal ABC described in the RFC applied to a Reno style algorithm. For advanced congestion control there is little change after leaving slow start. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_cong.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) (limited to 'net/ipv4/tcp_cong.c') diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 6d3e883b48f6..c7cc62c8dc12 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -192,17 +192,26 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, /* In "safe" area, increase. */ if (tp->snd_cwnd <= tp->snd_ssthresh) tcp_slow_start(tp); - else { - /* In dangerous area, increase slowly. - * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd - */ - if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - tp->snd_cwnd_cnt = 0; - } else - tp->snd_cwnd_cnt++; - } + + /* In dangerous area, increase slowly. */ + else if (sysctl_tcp_abc) { + /* RFC3465: Apppriate Byte Count + * increase once for each full cwnd acked + */ + if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) { + tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache; + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + } + } else { + /* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */ + if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + tp->snd_cwnd_cnt = 0; + } else + tp->snd_cwnd_cnt++; + } } EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid); -- cgit v1.2.2