From eaf80179e2036deb396c6988bfacc9975d49ded0 Mon Sep 17 00:00:00 2001 From: Andre Oppermann Date: Thu, 16 Feb 2006 19:38:07 +0000 Subject: [PATCH] Have TCP Inflight disable itself if the RTT is below a certain threshold. Inflight doesn't make sense on a LAN as it has trouble figuring out the maximal bandwidth because of the coarse tick granularity. The sysctl net.inet.tcp.inflight.rttthresh specifies the threshold in milliseconds below which inflight will disengage. It defaults to 10ms. Tested by: Joao Barros , Rich Murphey Sponsored by: TCP/IP Optimization Fundraise 2005 --- sys/netinet/tcp_input.c | 10 ++++++++++ sys/netinet/tcp_reass.c | 10 ++++++++++ sys/netinet/tcp_subr.c | 8 +++++++- sys/netinet/tcp_timer.h | 3 +++ sys/netinet/tcp_timewait.c | 8 +++++++- sys/netinet/tcp_var.h | 1 + 6 files changed, 38 insertions(+), 2 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index e71b6bdd085..d50333be6a8 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -1193,10 +1193,16 @@ after_listen: */ if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { + if (!tp->t_rttlow || + tp->t_rttlow > ticks - to.to_tsecr) + tp->t_rttlow = ticks - to.to_tsecr; tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || + tp->t_rttlow > ticks - tp->t_rtttime) + tp->t_rttlow = ticks - tp->t_rtttime; tcp_xmit_timer(tp, ticks - tp->t_rtttime); } @@ -2077,8 +2083,12 @@ process_ACK: */ if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { + if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr) + tp->t_rttlow = ticks - to.to_tsecr; tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) + tp->t_rttlow = ticks - tp->t_rtttime; tcp_xmit_timer(tp, ticks - tp->t_rtttime); } tcp_xmit_bandwidth_limit(tp, th->th_ack); diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c index e71b6bdd085..d50333be6a8 100644 --- a/sys/netinet/tcp_reass.c +++ b/sys/netinet/tcp_reass.c @@ -1193,10 +1193,16 @@ after_listen: */ if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { + if (!tp->t_rttlow || + tp->t_rttlow > ticks - to.to_tsecr) + tp->t_rttlow = ticks - to.to_tsecr; tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || + tp->t_rttlow > ticks - tp->t_rtttime) + tp->t_rttlow = ticks - tp->t_rtttime; tcp_xmit_timer(tp, ticks - tp->t_rtttime); } @@ -2077,8 +2083,12 @@ process_ACK: */ if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { + if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr) + tp->t_rttlow = ticks - to.to_tsecr; tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) + tp->t_rttlow = ticks - tp->t_rtttime; tcp_xmit_timer(tp, ticks - tp->t_rtttime); } tcp_xmit_bandwidth_limit(tp, th->th_ack); diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index 9267ea2656c..e61d54143b2 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -193,6 +193,11 @@ static int tcp_inflight_debug = 0; SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); +static int tcp_inflight_rttthresh; +SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, + &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", + "RTT threshold below which inflight will deactivate itself"); + static int tcp_inflight_min = 6144; SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); @@ -253,6 +258,7 @@ tcp_init() tcp_msl = TCPTV_MSL; tcp_rexmit_min = TCPTV_MIN; tcp_rexmit_slop = TCPTV_CPU_VAR; + tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); LIST_INIT(&tcb); @@ -1937,7 +1943,7 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) * If inflight_enable is disabled in the middle of a tcp connection, * make sure snd_bwnd is effectively disabled. */ - if (tcp_inflight_enable == 0) { + if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; tp->snd_bandwidth = 0; return; diff --git a/sys/netinet/tcp_timer.h b/sys/netinet/tcp_timer.h index c62060fe85c..d3d7c94ff3b 100644 --- a/sys/netinet/tcp_timer.h +++ b/sys/netinet/tcp_timer.h @@ -86,6 +86,9 @@ #define TCPTV_KEEPINTVL ( 75*hz) /* default probe interval */ #define TCPTV_KEEPCNT 8 /* max probes before drop */ +#define TCPTV_INFLIGHT_RTTTHRESH (10*hz/1000) /* below which inflight + disengages, in msec */ + /* * Minimum retransmit timer is 3 ticks, for algorithmic stability. * TCPT_RANGESET() will add another TCPTV_CPU_VAR to deal with diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c index 9267ea2656c..e61d54143b2 100644 --- a/sys/netinet/tcp_timewait.c +++ b/sys/netinet/tcp_timewait.c @@ -193,6 +193,11 @@ static int tcp_inflight_debug = 0; SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); +static int tcp_inflight_rttthresh; +SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, + &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", + "RTT threshold below which inflight will deactivate itself"); + static int tcp_inflight_min = 6144; SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); @@ -253,6 +258,7 @@ tcp_init() tcp_msl = TCPTV_MSL; tcp_rexmit_min = TCPTV_MIN; tcp_rexmit_slop = TCPTV_CPU_VAR; + tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); LIST_INIT(&tcb); @@ -1937,7 +1943,7 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) * If inflight_enable is disabled in the middle of a tcp connection, * make sure snd_bwnd is effectively disabled. */ - if (tcp_inflight_enable == 0) { + if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; tp->snd_bandwidth = 0; return; diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h index b1515ddf6d2..f9050df1d8a 100644 --- a/sys/netinet/tcp_var.h +++ b/sys/netinet/tcp_var.h @@ -199,6 +199,7 @@ struct tcpcb { tcp_seq sack_newdata; /* New data xmitted in this recovery episode starts at this seq number */ struct sackhint sackhint; /* SACK scoreboard hint */ + int t_rttlow; /* smallest observerved RTT */ }; #define IN_FASTRECOVERY(tp) (tp->t_flags & TF_FASTRECOVERY)