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Keep track of the number of samples through the srtt filter so that we

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know better when to cache values in the route, rather than relying on a
heuristic involving sequence numbers that broke when tcp_sendspace
was increased to 16k.
This commit is contained in:
Garrett Wollman 1995-06-29 18:11:24 +00:00
parent a5da5e632f
commit fc97827135
5 changed files with 23 additions and 21 deletions
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3
sys/netinet/tcp_input.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* From: @(#)tcp_input.c 8.5 (Berkeley) 4/10/94
* $Id: tcp_input.c,v 1.24 1995/05/11 01:41:06 davidg Exp $
* $Id: tcp_input.c,v 1.25 1995/05/30 08:09:55 rgrimes Exp $
*/
#ifndef TUBA_INCLUDE
@ -1814,6 +1814,7 @@ tcp_xmit_timer(tp, rtt)
register short delta;
tcpstat.tcps_rttupdated++;
tp->t_rttupdated++;
if (tp->t_srtt != 0) {
/*
* srtt is stored as fixed point with 3 bits after the

3
sys/netinet/tcp_reass.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* From: @(#)tcp_input.c 8.5 (Berkeley) 4/10/94
* $Id: tcp_input.c,v 1.24 1995/05/11 01:41:06 davidg Exp $
* $Id: tcp_input.c,v 1.25 1995/05/30 08:09:55 rgrimes Exp $
*/
#ifndef TUBA_INCLUDE
@ -1814,6 +1814,7 @@ tcp_xmit_timer(tp, rtt)
register short delta;
tcpstat.tcps_rttupdated++;
tp->t_rttupdated++;
if (tp->t_srtt != 0) {
/*
* srtt is stored as fixed point with 3 bits after the

17
sys/netinet/tcp_subr.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
* $Id: tcp_subr.c,v 1.11 1995/05/30 08:09:58 rgrimes Exp $
* $Id: tcp_subr.c,v 1.12 1995/06/19 16:45:33 wollman Exp $
*/
#include <sys/param.h>
@ -303,18 +303,17 @@ tcp_close(tp)
register struct rtentry *rt;
/*
* If we sent enough data to get some meaningful characteristics,
* save them in the routing entry. 'Enough' is arbitrarily
* defined as the sendpipesize (default 4K) * 16. This would
* give us 16 rtt samples assuming we only get one sample per
* window (the usual case on a long haul net). 16 samples is
* enough for the srtt filter to converge to within 5% of the correct
* value; fewer samples and we could save a very bogus rtt.
* If we got enough samples through the srtt filter,
* save the rtt and rttvar in the routing entry.
* 'Enough' is arbitrarily defined as the 16 samples.
* 16 samples is enough for the srtt filter to converge
* to within 5% of the correct value; fewer samples and
* we could save a very bogus rtt.
*
* Don't update the default route's characteristics and don't
* update anything that the user "locked".
*/
if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) &&
if (tp->t_rttupdated >= 16 &&
(rt = inp->inp_route.ro_rt) &&
((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) {
register u_long i = 0;

17
sys/netinet/tcp_timewait.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
* $Id: tcp_subr.c,v 1.11 1995/05/30 08:09:58 rgrimes Exp $
* $Id: tcp_subr.c,v 1.12 1995/06/19 16:45:33 wollman Exp $
*/
#include <sys/param.h>
@ -303,18 +303,17 @@ tcp_close(tp)
register struct rtentry *rt;
/*
* If we sent enough data to get some meaningful characteristics,
* save them in the routing entry. 'Enough' is arbitrarily
* defined as the sendpipesize (default 4K) * 16. This would
* give us 16 rtt samples assuming we only get one sample per
* window (the usual case on a long haul net). 16 samples is
* enough for the srtt filter to converge to within 5% of the correct
* value; fewer samples and we could save a very bogus rtt.
* If we got enough samples through the srtt filter,
* save the rtt and rttvar in the routing entry.
* 'Enough' is arbitrarily defined as the 16 samples.
* 16 samples is enough for the srtt filter to converge
* to within 5% of the correct value; fewer samples and
* we could save a very bogus rtt.
*
* Don't update the default route's characteristics and don't
* update anything that the user "locked".
*/
if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) &&
if (tp->t_rttupdated >= 16 &&
(rt = inp->inp_route.ro_rt) &&
((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) {
register u_long i = 0;

4
sys/netinet/tcp_var.h
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)tcp_var.h 8.3 (Berkeley) 4/10/94
* $Id: tcp_var.h,v 1.11 1995/04/09 01:29:29 davidg Exp $
* $Id: tcp_var.h,v 1.12 1995/06/19 16:45:33 wollman Exp $
*/
#ifndef _NETINET_TCP_VAR_H_
@ -139,6 +139,8 @@ struct tcpcb {
/* TUBA stuff */
caddr_t t_tuba_pcb; /* next level down pcb for TCP over z */
/* More RTT stuff */
u_long t_rttupdated; /* number of times rtt sampled */
};
/*