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, 21 insertions, 17 deletions

diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index 4fba1a2..3290c0c 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -87,7 +87,8 @@ static int	sysctl_dumpentry(struct radix_node *rn, void *vw);
 static int	sysctl_iflist(int af, struct walkarg *w);
 static int	sysctl_ifmalist(int af, struct walkarg *w);
 static int	route_output(struct mbuf *, struct socket *);
-static void	rt_setmetrics(u_long, struct rt_metrics *, struct rt_metrics *);
+static void	rt_setmetrics(u_long, struct rt_metrics *, struct rt_metrics_lite *);
+static void	rt_getmetrics(struct rt_metrics_lite *, struct rt_metrics *);
 static void	rt_dispatch(struct mbuf *, struct sockaddr *);
 
 /*
@@ -355,9 +356,6 @@ route_output(m, so)
 			RT_LOCK(saved_nrt);
 			rt_setmetrics(rtm->rtm_inits,
 				&rtm->rtm_rmx, &saved_nrt->rt_rmx);
-			saved_nrt->rt_rmx.rmx_locks &= ~(rtm->rtm_inits);
-			saved_nrt->rt_rmx.rmx_locks |=
-				(rtm->rtm_inits & rtm->rtm_rmx.rmx_locks);
 			RT_REMREF(saved_nrt);
 			saved_nrt->rt_genmask = info.rti_info[RTAX_GENMASK];
 			RT_UNLOCK(saved_nrt);
@@ -428,7 +426,7 @@ route_output(m, so)
 			(void)rt_msg2(rtm->rtm_type, &info, (caddr_t)rtm,
 				(struct walkarg *)0);
 			rtm->rtm_flags = rt->rt_flags;
-			rtm->rtm_rmx = rt->rt_rmx;
+			rt_getmetrics(&rt->rt_rmx, &rtm->rtm_rmx);
 			rtm->rtm_addrs = info.rti_addrs;
 			break;
 
@@ -478,9 +476,7 @@ route_output(m, so)
 				rt->rt_genmask = info.rti_info[RTAX_GENMASK];
 			/* FALLTHROUGH */
 		case RTM_LOCK:
-			rt->rt_rmx.rmx_locks &= ~(rtm->rtm_inits);
-			rt->rt_rmx.rmx_locks |=
-				(rtm->rtm_inits & rtm->rtm_rmx.rmx_locks);
+			/* We don't support locks anymore */
 			break;
 		}
 		RT_UNLOCK(rt);
@@ -542,20 +538,28 @@ flush:
 }
 
 static void
-rt_setmetrics(u_long which, struct rt_metrics *in, struct rt_metrics *out)
+rt_setmetrics(u_long which, struct rt_metrics *in, struct rt_metrics_lite *out)
 {
 #define metric(f, e) if (which & (f)) out->e = in->e;
-	metric(RTV_RPIPE, rmx_recvpipe);
-	metric(RTV_SPIPE, rmx_sendpipe);
-	metric(RTV_SSTHRESH, rmx_ssthresh);
-	metric(RTV_RTT, rmx_rtt);
-	metric(RTV_RTTVAR, rmx_rttvar);
-	metric(RTV_HOPCOUNT, rmx_hopcount);
+	/*
+	 * Only these are stored in the routing entry since introduction
+	 * of tcp hostcache. The rest is ignored.
+	 */
 	metric(RTV_MTU, rmx_mtu);
 	metric(RTV_EXPIRE, rmx_expire);
 #undef metric
 }
 
+static void
+rt_getmetrics(struct rt_metrics_lite *in, struct rt_metrics *out)
+{
+#define metric(e) out->e = in->e;
+	bzero(out, sizeof(*out));
+	metric(rmx_mtu);
+	metric(rmx_expire);
+#undef metric
+}
+
 #define ROUNDUP(a) \
 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
 
@@ -948,8 +952,8 @@ sysctl_dumpentry(struct radix_node *rn, void *vw)
 		struct rt_msghdr *rtm = (struct rt_msghdr *)w->w_tmem;
 
 		rtm->rtm_flags = rt->rt_flags;
-		rtm->rtm_use = rt->rt_use;
-		rtm->rtm_rmx = rt->rt_rmx;
+		rtm->rtm_use = rt->rt_rmx.rmx_pksent;
+		rt_getmetrics(&rt->rt_rmx, &rtm->rtm_rmx);
 		rtm->rtm_index = rt->rt_ifp->if_index;
 		rtm->rtm_errno = rtm->rtm_pid = rtm->rtm_seq = 0;
 		rtm->rtm_addrs = info.rti_addrs;