tcp_input.c - keep track of how many times a route contained a cached rtt

	or ssthresh that we were able to use

tcp_var.h - declare tcpstat entries for above; declare tcp_{send,recv}space

in_rmx.c - fill in the MTU and pipe sizes with the defaults TCP would have
	used anyway in the absence of values here

4 files changed, 61 insertions, 17 deletions

diff --git a/sys/netinet/in_rmx.c b/sys/netinet/in_rmx.c
index a0fcbb4..4768362 100644
--- a/sys/netinet/in_rmx.c
+++ b/sys/netinet/in_rmx.c
@@ -26,7 +26,7 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: in_rmx.c,v 1.13 1995/05/30 08:09:31 rgrimes Exp $
+ * $Id: in_rmx.c,v 1.14 1995/06/21 19:48:53 wollman Exp $
  */
 
 /*
@@ -57,6 +57,15 @@
 #include <netinet/in_systm.h>
 #include <netinet/in_var.h>
 
+#include <netinet/ip.h>
+#include <netinet/ip_var.h>
+
+#include <netinet/tcp.h>
+#include <netinet/tcp_seq.h>
+#include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
+#include <netinet/tcpip.h>
+
 #define RTPRF_OURS		RTF_PROTO3	/* set on routes we manage */
 
 /*
@@ -67,17 +76,45 @@ in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
 	    struct radix_node *treenodes)
 {
 	struct rtentry *rt = (struct rtentry *)treenodes;
+	struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
 
 	/*
 	 * For IP, all unicast non-host routes are automatically cloning.
 	 */
 	if(!(rt->rt_flags & (RTF_HOST | RTF_CLONING))) {
-		struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
 		if(!IN_MULTICAST(ntohl(sin->sin_addr.s_addr))) {
 			rt->rt_flags |= RTF_PRCLONING;
 		}
 	}
 
+	/*
+	 * We also specify a send and receive pipe size for every
+	 * route added, to help TCP a bit.  TCP doesn't actually
+	 * want a true pipe size, which would be prohibitive in memory
+	 * costs and is hard to compute anyway; it simply uses these
+	 * values to size its buffers.  So, we fill them in with the
+	 * same values that TCP would have used anyway, and allow the
+	 * installing program or the link layer to override these values
+	 * as it sees fit.  This will hopefully allow TCP more
+	 * opportunities to save its ssthresh value.
+	 */
+	if (!rt->rt_rmx.rmx_sendpipe && !(rt->rt_rmx.rmx_locks & RTV_SPIPE))
+		rt->rt_rmx.rmx_sendpipe = tcp_sendspace;
+
+	if (!rt->rt_rmx.rmx_recvpipe && !(rt->rt_rmx.rmx_locks & RTV_RPIPE))
+		rt->rt_rmx.rmx_recvpipe = tcp_recvspace;
+
+	/*
+	 * Finally, set an MTU, again duplicating logic in TCP.
+	 * The in_localaddr() business will go away when we have
+	 * proper PMTU discovery.
+	 */
+	if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) 
+	    && rt->rt_ifp)
+		rt->rt_rmx.rmx_mtu = (in_localaddr(sin->sin_addr)
+				      ? rt->rt_ifp->if_mtu
+				      : tcp_mssdflt + sizeof(struct tcpiphdr));
+
 	return rn_addroute(v_arg, n_arg, head, treenodes);
 }
 
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index eb459c2..eb2f346 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	From: @(#)tcp_input.c	8.5 (Berkeley) 4/10/94
- *	$Id: tcp_input.c,v 1.25 1995/05/30 08:09:55 rgrimes Exp $
+ *	$Id: tcp_input.c,v 1.26 1995/06/29 18:11:22 wollman Exp $
  */
 
 #ifndef TUBA_INCLUDE
@@ -1950,7 +1950,6 @@ tcp_mss(tp, offer)
 		offer = max(offer, 64);
 	taop->tao_mssopt = offer;
 
-#ifdef RTV_MTU	/* if route characteristics exist ... */
 	/*
 	 * While we're here, check if there's an initial rtt
 	 * or rttvar.  Convert from the route-table units
@@ -1964,13 +1963,16 @@ tcp_mss(tp, offer)
 		if (rt->rt_rmx.rmx_locks & RTV_RTT)
 			tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ);
 		tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
-		if (rt->rt_rmx.rmx_rttvar)
+		tcpstat.tcps_usedrtt++;
+		if (rt->rt_rmx.rmx_rttvar) {
 			tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
 			    (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE));
-		else
+			tcpstat.tcps_usedrttvar++;
+		} else {
 			/* default variation is +- 1 rtt */
 			tp->t_rttvar =
 			    tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
+		}
 		TCPT_RANGESET(tp->t_rxtcur,
 		    ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
 		    tp->t_rttmin, TCPTV_REXMTMAX);
@@ -1981,7 +1983,6 @@ tcp_mss(tp, offer)
 	if (rt->rt_rmx.rmx_mtu)
 		mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr);
 	else
-#endif /* RTV_MTU */
 	{
 		mss = ifp->if_mtu - sizeof(struct tcpiphdr);
 		if (!in_localaddr(inp->inp_faddr))
@@ -2054,7 +2055,6 @@ tcp_mss(tp, offer)
 	if (!in_localaddr(inp->inp_faddr))
 		tp->snd_cwnd = mss;
 
-#ifdef RTV_SSTHRESH
 	if (rt->rt_rmx.rmx_ssthresh) {
 		/*
 		 * There's some sort of gateway or interface
@@ -2063,8 +2063,8 @@ tcp_mss(tp, offer)
 		 * threshold to no less than 2*mss.
 		 */
 		tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
+		tcpstat.tcps_usedssthresh++;
 	}
-#endif
 }
 
 /*
diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c
index eb459c2..eb2f346 100644
--- a/sys/netinet/tcp_reass.c
+++ b/sys/netinet/tcp_reass.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	From: @(#)tcp_input.c	8.5 (Berkeley) 4/10/94
- *	$Id: tcp_input.c,v 1.25 1995/05/30 08:09:55 rgrimes Exp $
+ *	$Id: tcp_input.c,v 1.26 1995/06/29 18:11:22 wollman Exp $
  */
 
 #ifndef TUBA_INCLUDE
@@ -1950,7 +1950,6 @@ tcp_mss(tp, offer)
 		offer = max(offer, 64);
 	taop->tao_mssopt = offer;
 
-#ifdef RTV_MTU	/* if route characteristics exist ... */
 	/*
 	 * While we're here, check if there's an initial rtt
 	 * or rttvar.  Convert from the route-table units
@@ -1964,13 +1963,16 @@ tcp_mss(tp, offer)
 		if (rt->rt_rmx.rmx_locks & RTV_RTT)
 			tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ);
 		tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
-		if (rt->rt_rmx.rmx_rttvar)
+		tcpstat.tcps_usedrtt++;
+		if (rt->rt_rmx.rmx_rttvar) {
 			tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
 			    (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE));
-		else
+			tcpstat.tcps_usedrttvar++;
+		} else {
 			/* default variation is +- 1 rtt */
 			tp->t_rttvar =
 			    tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
+		}
 		TCPT_RANGESET(tp->t_rxtcur,
 		    ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
 		    tp->t_rttmin, TCPTV_REXMTMAX);
@@ -1981,7 +1983,6 @@ tcp_mss(tp, offer)
 	if (rt->rt_rmx.rmx_mtu)
 		mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr);
 	else
-#endif /* RTV_MTU */
 	{
 		mss = ifp->if_mtu - sizeof(struct tcpiphdr);
 		if (!in_localaddr(inp->inp_faddr))
@@ -2054,7 +2055,6 @@ tcp_mss(tp, offer)
 	if (!in_localaddr(inp->inp_faddr))
 		tp->snd_cwnd = mss;
 
-#ifdef RTV_SSTHRESH
 	if (rt->rt_rmx.rmx_ssthresh) {
 		/*
 		 * There's some sort of gateway or interface
@@ -2063,8 +2063,8 @@ tcp_mss(tp, offer)
 		 * threshold to no less than 2*mss.
 		 */
 		tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
+		tcpstat.tcps_usedssthresh++;
 	}
-#endif
 }
 
 /*
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 8a9c621..6b69091 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)tcp_var.h	8.3 (Berkeley) 4/10/94
- * $Id: tcp_var.h,v 1.12 1995/06/19 16:45:33 wollman Exp $
+ * $Id: tcp_var.h,v 1.13 1995/06/29 18:11:24 wollman Exp $
  */
 
 #ifndef _NETINET_TCP_VAR_H_
@@ -282,6 +282,9 @@ struct	tcpstat {
 	u_long	tcps_cachedrtt;		/* times cached RTT in route updated */
 	u_long	tcps_cachedrttvar;	/* times cached rttvar updated */
 	u_long	tcps_cachedssthresh;	/* times cached ssthresh updated */
+	u_long	tcps_usedrtt;		/* times RTT initialized from route */
+	u_long	tcps_usedrttvar;	/* times RTTVAR initialized from rt */
+	u_long	tcps_usedssthresh;	/* times ssthresh initialized from rt*/
 };
 
 /*
@@ -368,6 +371,10 @@ struct tcpcb *
 int	 tcp_usrreq __P((struct socket *,
 	    int, struct mbuf *, struct mbuf *, struct mbuf *));
 void	 tcp_xmit_timer __P((struct tcpcb *, int));
+
+extern	u_long tcp_sendspace;
+extern	u_long tcp_recvspace;
+
 #endif /* KERNEL */
 
 #endif /* _NETINET_TCP_VAR_H_ */