From 7faffa1c7fb9b8e8917e3225d4e2638270c0a48b Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 10 Nov 2005 17:07:24 -0800 Subject: [PATCH] [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 --- include/net/tcp.h | 10 ++++++++++ net/ipv4/tcp_bic.c | 10 ++++------ net/ipv4/tcp_cong.c | 11 +++++------ net/ipv4/tcp_highspeed.c | 7 +++---- net/ipv4/tcp_htcp.c | 11 +++++------ net/ipv4/tcp_scalable.c | 11 +++++------ net/ipv4/tcp_vegas.c | 42 +++++++++++------------------------------- 7 files changed, 43 insertions(+), 59 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 15bdbc6..54c39988 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -765,6 +765,16 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk) (tp->snd_cwnd >> 2))); } +/* + * Linear increase during slow start + */ +static inline void tcp_slow_start(struct tcp_sock *tp) +{ + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; +} + + static inline void tcp_sync_left_out(struct tcp_sock *tp) { if (tp->rx_opt.sack_ok && diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c index 5af99b3..1d0cd86 100644 --- a/net/ipv4/tcp_bic.c +++ b/net/ipv4/tcp_bic.c @@ -220,14 +220,12 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, 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 { + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + else { bictcp_update(ca, tp->snd_cwnd); - /* In dangerous area, increase slowly. + /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */ if (tp->snd_cwnd_cnt >= ca->cnt) { diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 0705b49..6d3e883 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) { diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c index 5e56ad3..82b3c18 100644 --- a/net/ipv4/tcp_highspeed.c +++ b/net/ipv4/tcp_highspeed.c @@ -119,10 +119,9 @@ static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt, if (!tcp_is_cwnd_limited(sk, in_flight)) return; - if (tp->snd_cwnd <= tp->snd_ssthresh) { - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - } else { + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + else { /* Update AIMD parameters */ if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) { while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd && diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c index 404a326..3284cfb 100644 --- a/net/ipv4/tcp_htcp.c +++ b/net/ipv4/tcp_htcp.c @@ -210,11 +210,10 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, 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 { + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + else { + measure_rtt(sk); /* keep track of number of round-trip times since last backoff event */ @@ -224,7 +223,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, htcp_alpha_update(ca); } - /* In dangerous area, increase slowly. + /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd */ if ((tp->snd_cwnd_cnt++ * ca->alpha)>>7 >= tp->snd_cwnd) { diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c index a2fd256..26d7486 100644 --- a/net/ipv4/tcp_scalable.c +++ b/net/ipv4/tcp_scalable.c @@ -24,17 +24,16 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 rtt, if (!tcp_is_cwnd_limited(sk, in_flight)) return; - if (tp->snd_cwnd <= tp->snd_ssthresh) { - tp->snd_cwnd++; - } else { + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + else { tp->snd_cwnd_cnt++; if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){ - tp->snd_cwnd++; + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; tp->snd_cwnd_cnt = 0; } } - tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp); - tp->snd_cwnd_stamp = tcp_time_stamp; } static u32 tcp_scalable_ssthresh(struct sock *sk) diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c index 93c5f92..4376814 100644 --- a/net/ipv4/tcp_vegas.c +++ b/net/ipv4/tcp_vegas.c @@ -236,8 +236,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, /* We don't have enough RTT samples to do the Vegas * calculation, so we'll behave like Reno. */ - if (tp->snd_cwnd > tp->snd_ssthresh) - tp->snd_cwnd++; + tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, cnt); } else { u32 rtt, target_cwnd, diff; @@ -275,7 +274,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, */ diff = (old_wnd << V_PARAM_SHIFT) - target_cwnd; - if (tp->snd_cwnd < tp->snd_ssthresh) { + if (tp->snd_cwnd <= tp->snd_ssthresh) { /* Slow start. */ if (diff > gamma) { /* Going too fast. Time to slow down @@ -295,6 +294,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, V_PARAM_SHIFT)+1); } + tcp_slow_start(tp); } else { /* Congestion avoidance. */ u32 next_snd_cwnd; @@ -327,37 +327,17 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, else if (next_snd_cwnd < tp->snd_cwnd) tp->snd_cwnd--; } - } - /* Wipe the slate clean for the next RTT. */ - vegas->cntRTT = 0; - vegas->minRTT = 0x7fffffff; + if (tp->snd_cwnd < 2) + tp->snd_cwnd = 2; + else if (tp->snd_cwnd > tp->snd_cwnd_clamp) + tp->snd_cwnd = tp->snd_cwnd_clamp; + } } - /* The following code is executed for every ack we receive, - * except for conditions checked in should_advance_cwnd() - * before the call to tcp_cong_avoid(). Mainly this means that - * we only execute this code if the ack actually acked some - * data. - */ - - /* If we are in slow start, increase our cwnd in response to this ACK. - * (If we are not in slow start then we are in congestion avoidance, - * and adjust our congestion window only once per RTT. See the code - * above.) - */ - if (tp->snd_cwnd <= tp->snd_ssthresh) - tp->snd_cwnd++; - - /* to keep cwnd from growing without bound */ - tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp); - - /* Make sure that we are never so timid as to reduce our cwnd below - * 2 MSS. - * - * Going below 2 MSS would risk huge delayed ACKs from our receiver. - */ - tp->snd_cwnd = max(tp->snd_cwnd, 2U); + /* Wipe the slate clean for the next RTT. */ + vegas->cntRTT = 0; + vegas->minRTT = 0x7fffffff; } /* Extract info for Tcp socket info provided via netlink. */ -- 2.7.4