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 <joao.barros-at-gmail.com>, Rich Murphey <rich-at-whiteoaklabs.com> Sponsored by: TCP/IP Optimization Fundraise 2005
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commit
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=155767
@ -1193,10 +1193,16 @@ tcp_input(m, off0)
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*/
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if ((to.to_flags & TOF_TS) != 0 &&
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to.to_tsecr) {
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if (!tp->t_rttlow ||
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tp->t_rttlow > ticks - to.to_tsecr)
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tp->t_rttlow = ticks - to.to_tsecr;
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tcp_xmit_timer(tp,
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ticks - to.to_tsecr + 1);
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} else if (tp->t_rtttime &&
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SEQ_GT(th->th_ack, tp->t_rtseq)) {
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if (!tp->t_rttlow ||
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tp->t_rttlow > ticks - tp->t_rtttime)
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tp->t_rttlow = ticks - tp->t_rtttime;
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tcp_xmit_timer(tp,
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ticks - tp->t_rtttime);
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}
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@ -2077,8 +2083,12 @@ tcp_input(m, off0)
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*/
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if ((to.to_flags & TOF_TS) != 0 &&
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to.to_tsecr) {
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if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr)
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tp->t_rttlow = ticks - to.to_tsecr;
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tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
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} else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
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if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime)
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tp->t_rttlow = ticks - tp->t_rtttime;
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tcp_xmit_timer(tp, ticks - tp->t_rtttime);
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}
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tcp_xmit_bandwidth_limit(tp, th->th_ack);
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@ -1193,10 +1193,16 @@ tcp_input(m, off0)
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*/
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if ((to.to_flags & TOF_TS) != 0 &&
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to.to_tsecr) {
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if (!tp->t_rttlow ||
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tp->t_rttlow > ticks - to.to_tsecr)
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tp->t_rttlow = ticks - to.to_tsecr;
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tcp_xmit_timer(tp,
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ticks - to.to_tsecr + 1);
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} else if (tp->t_rtttime &&
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SEQ_GT(th->th_ack, tp->t_rtseq)) {
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if (!tp->t_rttlow ||
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tp->t_rttlow > ticks - tp->t_rtttime)
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tp->t_rttlow = ticks - tp->t_rtttime;
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tcp_xmit_timer(tp,
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ticks - tp->t_rtttime);
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}
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@ -2077,8 +2083,12 @@ tcp_input(m, off0)
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*/
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if ((to.to_flags & TOF_TS) != 0 &&
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to.to_tsecr) {
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if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr)
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tp->t_rttlow = ticks - to.to_tsecr;
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tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
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} else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
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if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime)
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tp->t_rttlow = ticks - tp->t_rtttime;
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tcp_xmit_timer(tp, ticks - tp->t_rtttime);
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}
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tcp_xmit_bandwidth_limit(tp, th->th_ack);
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@ -193,6 +193,11 @@ static int tcp_inflight_debug = 0;
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SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW,
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&tcp_inflight_debug, 0, "Debug TCP inflight calculations");
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static int tcp_inflight_rttthresh;
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SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I",
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"RTT threshold below which inflight will deactivate itself");
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static int tcp_inflight_min = 6144;
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SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW,
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&tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
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@ -253,6 +258,7 @@ tcp_init()
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tcp_msl = TCPTV_MSL;
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tcp_rexmit_min = TCPTV_MIN;
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tcp_rexmit_slop = TCPTV_CPU_VAR;
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tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH;
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INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
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LIST_INIT(&tcb);
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@ -1937,7 +1943,7 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
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* If inflight_enable is disabled in the middle of a tcp connection,
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* make sure snd_bwnd is effectively disabled.
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*/
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if (tcp_inflight_enable == 0) {
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if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) {
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tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
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tp->snd_bandwidth = 0;
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return;
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@ -86,6 +86,9 @@
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#define TCPTV_KEEPINTVL ( 75*hz) /* default probe interval */
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#define TCPTV_KEEPCNT 8 /* max probes before drop */
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#define TCPTV_INFLIGHT_RTTTHRESH (10*hz/1000) /* below which inflight
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disengages, in msec */
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/*
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* Minimum retransmit timer is 3 ticks, for algorithmic stability.
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* TCPT_RANGESET() will add another TCPTV_CPU_VAR to deal with
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@ -193,6 +193,11 @@ static int tcp_inflight_debug = 0;
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SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW,
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&tcp_inflight_debug, 0, "Debug TCP inflight calculations");
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static int tcp_inflight_rttthresh;
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SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I",
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"RTT threshold below which inflight will deactivate itself");
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static int tcp_inflight_min = 6144;
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SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW,
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&tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
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@ -253,6 +258,7 @@ tcp_init()
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tcp_msl = TCPTV_MSL;
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tcp_rexmit_min = TCPTV_MIN;
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tcp_rexmit_slop = TCPTV_CPU_VAR;
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tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH;
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INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
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LIST_INIT(&tcb);
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@ -1937,7 +1943,7 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
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* If inflight_enable is disabled in the middle of a tcp connection,
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* make sure snd_bwnd is effectively disabled.
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*/
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if (tcp_inflight_enable == 0) {
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if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) {
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tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
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tp->snd_bandwidth = 0;
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return;
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@ -199,6 +199,7 @@ struct tcpcb {
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tcp_seq sack_newdata; /* New data xmitted in this recovery
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episode starts at this seq number */
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struct sackhint sackhint; /* SACK scoreboard hint */
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int t_rttlow; /* smallest observerved RTT */
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};
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#define IN_FASTRECOVERY(tp) (tp->t_flags & TF_FASTRECOVERY)
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