Introduce tcp_hostcache and remove the tcp specific metrics from

the routing table.  Move all usage and references in the tcp stack
from the routing table metrics to the tcp hostcache.

It caches measured parameters of past tcp sessions to provide better
initial start values for following connections from or to the same
source or destination.  Depending on the network parameters to/from
the remote host this can lead to significant speedups for new tcp
connections after the first one because they inherit and shortcut
the learning curve.

tcp_hostcache is designed for multiple concurrent access in SMP
environments with high contention and is hash indexed by remote
ip address.

It removes significant locking requirements from the tcp stack with
regard to the routing table.

Reviewed by:	sam (mentor), bms
Reviewed by:	-net, -current, core@kame.net (IPv6 parts)
Approved by:	re (scottl)

1 files changed, 33 insertions, 11 deletions

diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 2e5b3fa..ddcfd3c 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -213,8 +213,6 @@ struct syncache {
 	struct 		tcpcb *sc_tp;		/* tcb for listening socket */
 	struct		mbuf *sc_ipopts;	/* source route */
 	struct 		in_conninfo sc_inc;	/* addresses */
-#define sc_route	sc_inc.inc_route
-#define sc_route6	sc_inc.inc6_route
 	u_int32_t	sc_tsrecent;
 	tcp_cc		sc_cc_send;		/* holds CC or CCnew */
 	tcp_cc		sc_cc_recv;
@@ -232,7 +230,6 @@ struct syncache {
 #define SCF_TIMESTAMP	0x04			/* negotiated timestamps */
 #define SCF_CC		0x08			/* negotiated CC */
 #define SCF_UNREACH	0x10			/* icmp unreachable received */
-#define SCF_KEEPROUTE	0x20			/* keep cloned route */
 	TAILQ_ENTRY(syncache)	sc_hash;
 	TAILQ_ENTRY(syncache)	sc_timerq;
 };
@@ -242,6 +239,17 @@ struct syncache_head {
 	u_int		sch_length;
 };
 
+struct hc_metrics_lite {	/* must stay in sync with hc_metrics */
+	u_long	rmx_mtu;	/* MTU for this path */
+	u_long	rmx_ssthresh;	/* outbound gateway buffer limit */
+	u_long	rmx_rtt;	/* estimated round trip time */
+	u_long	rmx_rttvar;	/* estimated rtt variance */
+	u_long	rmx_bandwidth;	/* estimated bandwidth */
+	u_long	rmx_cwnd;	/* congestion window */
+	u_long	rmx_sendpipe;   /* outbound delay-bandwidth product */
+	u_long	rmx_recvpipe;   /* inbound delay-bandwidth product */
+};
+
 struct tcptw {
 	struct inpcb	*tw_inpcb;	/* XXX back pointer to internet pcb */
 	tcp_seq		snd_nxt;
@@ -260,8 +268,7 @@ struct tcptw {
 };
  
 /*
- * The TAO cache entry which is stored in the protocol family specific
- * portion of the route metrics.
+ * The TAO cache entry which is stored in the tcp hostcache.
  */
 struct rmxp_tao {
 	tcp_cc	tao_cc;			/* latest CC in valid SYN */
@@ -274,7 +281,6 @@ struct rmxp_tao {
 #define	TAOF_UNDEF	0		/* we don't know yet */
 #endif /* notyet */
 };
-#define rmx_taop(r)	((struct rmxp_tao *)(r).rmx_filler)
 
 #define	intotcpcb(ip)	((struct tcpcb *)(ip)->inp_ppcb)
 #define	intotw(ip)	((struct tcptw *)(ip)->inp_ppcb)
@@ -401,6 +407,9 @@ struct	tcpstat {
 	u_long	tcps_sc_zonefail;	/* zalloc() failed */
 	u_long	tcps_sc_sendcookie;	/* SYN cookie sent */
 	u_long	tcps_sc_recvcookie;	/* SYN cookie received */
+
+	u_long	tcps_hc_added;		/* entry added to hostcache */
+	u_long	tcps_hc_bucketoverflow;	/* hostcache per bucket limit hit */
 };
 
 /*
@@ -451,6 +460,7 @@ struct	xtcpcb {
 	{ "pcblist", CTLTYPE_STRUCT }, \
 	{ "delacktime", CTLTYPE_INT }, \
 	{ "v6mssdflt", CTLTYPE_INT }, \
+	{ "maxid", CTLTYPE_INT }, \
 }
 
 
@@ -482,12 +492,12 @@ struct tcpcb *
 	 tcp_drop(struct tcpcb *, int);
 void	 tcp_drain(void);
 void	 tcp_fasttimo(void);
-struct rmxp_tao *
-	 tcp_gettaocache(struct in_conninfo *);
 void	 tcp_init(void);
 void	 tcp_input(struct mbuf *, int);
+u_long	 tcp_maxmtu(struct in_conninfo *);
+u_long	 tcp_maxmtu6(struct in_conninfo *);
 void	 tcp_mss(struct tcpcb *, int);
-int	 tcp_mssopt(struct tcpcb *);
+int	 tcp_mssopt(struct in_conninfo *);
 struct inpcb *	 
 	 tcp_drop_syn_sent(struct inpcb *, int);
 struct inpcb *
@@ -500,8 +510,6 @@ struct inpcb *
 void	 tcp_respond(struct tcpcb *, void *,
 	    struct tcphdr *, struct mbuf *, tcp_seq, tcp_seq, int);
 int	 tcp_twrespond(struct tcptw *, struct socket *, struct mbuf *, int);
-struct rtentry *
-	 tcp_rtlookup(struct in_conninfo *);
 void	 tcp_setpersist(struct tcpcb *);
 void	 tcp_slowtimo(void);
 struct tcptemp *
@@ -519,6 +527,20 @@ int	 syncache_add(struct in_conninfo *, struct tcpopt *,
 	     struct tcphdr *, struct socket **, struct mbuf *);
 void	 syncache_chkrst(struct in_conninfo *, struct tcphdr *);
 void	 syncache_badack(struct in_conninfo *);
+/*
+ * All tcp_hc_* functions are IPv4 and IPv6 (via in_conninfo)
+ */
+void	 tcp_hc_init(void);
+void	 tcp_hc_get(struct in_conninfo *, struct hc_metrics_lite *);
+u_long	 tcp_hc_getmtu(struct in_conninfo *);
+void	 tcp_hc_gettao(struct in_conninfo *, struct rmxp_tao *);
+void	 tcp_hc_updatemtu(struct in_conninfo *, u_long);
+void	 tcp_hc_update(struct in_conninfo *, struct hc_metrics_lite *);
+void	 tcp_hc_updatetao(struct in_conninfo *, int, tcp_cc, u_short);
+/* update which tao field */
+#define	TCP_HC_TAO_CC		0x1
+#define TCP_HC_TAO_CCSENT	0x2
+#define TCP_HC_TAO_MSSOPT	0x3
 
 extern	struct pr_usrreqs tcp_usrreqs;
 extern	u_long tcp_sendspace;