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Code Issues Releases Activity

Have TCP Inflight disable itself if the RTT is below a certain

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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
This commit is contained in:
Andre Oppermann 2006-02-16 19:38:07 +00:00
parent e3989d3ebf
commit eaf80179e2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=155767
6 changed files with 38 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
sys/netinet/tcp_input.c
View File

@ -1193,10 +1193,16 @@ tcp_input(m, off0)
*/
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 @@ tcp_input(m, off0)
*/
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);

10
sys/netinet/tcp_reass.c
View File

@ -1193,10 +1193,16 @@ tcp_input(m, off0)
*/
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 @@ tcp_input(m, off0)
*/
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);

8
sys/netinet/tcp_subr.c
View File

@ -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;

3
sys/netinet/tcp_timer.h
View File

@ -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

8
sys/netinet/tcp_timewait.c
View File

@ -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;

1
sys/netinet/tcp_var.h
View File

@ -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)