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In the CWM code, don't use the Floyd initial window computation as

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the burst size allowed, but rather a fixed number of packets, as
described in the Internet Draft.  Default allowed burst is 4 packets,
per the Draft.

Make the use of CWM and the allowed burst size tunable via sysctl.
This commit is contained in:
thorpej 1998-04-30 18:27:20 +00:00
parent e81920fa23
commit ce40806e29
2 changed files with 16 additions and 9 deletions
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13
sys/netinet/tcp_output.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: tcp_output.c,v 1.35 1998/04/29 03:44:12 kml Exp $ */
/* $NetBSD: tcp_output.c,v 1.36 1998/04/30 18:27:20 thorpej Exp $ */
/*-
* Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@ -110,13 +110,12 @@ extern struct mbuf *m_copypack();
#define MAX_TCPOPTLEN 32 /* max # bytes that go in options */
/*
* Knob to enable Congestion Window Monitoring.
* Knob to enable Congestion Window Monitoring, and control the
* the burst size it allows. Default burst is 4 packets, per
* the Internet draft.
*/
#ifdef TCP_CWM
int tcp_cwm = 1;
#else
int tcp_cwm = 0;
#endif
int tcp_cwm_burstsize = 4;
static __inline void tcp_segsize __P((struct tcpcb *, int *, int *));
static __inline void
@ -199,7 +198,7 @@ tcp_output(tp)
* been acknowledged (i.e. transmission is idle).
*/
tp->snd_cwnd = min(tp->snd_cwnd,
TCP_INITIAL_WINDOW(tcp_init_win, txsegsize) +
(tcp_cwm_burstsize * txsegsize) +
(tp->snd_nxt - tp->snd_una));
} else {
if (idle && tp->t_idle >= tp->t_rxtcur) {

12
sys/netinet/tcp_var.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: tcp_var.h,v 1.44 1998/04/30 17:55:27 thorpej Exp $ */
/* $NetBSD: tcp_var.h,v 1.45 1998/04/30 18:27:21 thorpej Exp $ */
/*-
* Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@ -384,7 +384,9 @@ struct tcpstat {
#define TCPCTL_WSCALE 11 /* RFC1323 window scaling */
#define TCPCTL_TSTAMP 12 /* RFC1323 timestamps */
#define TCPCTL_COMPAT_42 13 /* 4.2BSD TCP bug work-arounds */
#define TCPCTL_MAXID 14
#define TCPCTL_CWM 14 /* Congestion Window Monitoring */
#define TCPCTL_CWM_BURSTSIZE 15 /* burst size allowed by CWM */
#define TCPCTL_MAXID 16
#define TCPCTL_NAMES { \
{ 0, 0 }, \
@ -401,6 +403,8 @@ struct tcpstat {
{ "win_scale", CTLTYPE_INT }, \
{ "timestamps", CTLTYPE_INT }, \
{ "compat_42", CTLTYPE_INT }, \
{ "cwm", CTLTYPE_INT }, \
{ "cwm_burstsize", CTLTYPE_INT }, \
}
#ifdef _KERNEL
@ -415,6 +419,8 @@ extern int tcp_mssdflt; /* default seg size */
extern int tcp_init_win; /* initial window */
extern int tcp_mss_ifmtu; /* take MSS from interface, not in_maxmtu */
extern int tcp_compat_42; /* work around ancient broken TCP peers */
extern int tcp_cwm; /* enable Congestion Window Monitoring */
extern int tcp_cwm_burstsize; /* burst size allowed by CWM */
extern int tcp_syn_cache_limit; /* max entries for compressed state engine */
extern int tcp_syn_bucket_limit;/* max entries per hash bucket */
extern int tcp_syn_cache_interval; /* compressed state timer */
@ -439,6 +445,8 @@ extern u_long syn_cache_count;
&tcp_do_win_scale, \
&tcp_do_timestamps, \
&tcp_compat_42, \
&tcp_cwm, \
&tcp_cwm_burstsize, \
}
int tcp_attach __P((struct socket *));