devip: cache arp entry in Routehint

Instead of having to do an arp hash table lookup for each
outgoing ip packet, forward the Routehint pointer to the
medium's bwrite() function and let it cache the arp entry
pointer.

This avoids route and arp hash table lookups for tcp, il
and connection oriented udp.

It also allows us to avoid multiple route and arp table
lookups for the retransmits once an arp/neighbour solicitation
response arrives.

1 files changed, 35 insertions, 10 deletions

diff --git a/sys/src/9/ip/arp.c b/sys/src/9/ip/arp.c
index f74d1b6f8..08c934dbe 100644
--- a/sys/src/9/ip/arp.c
+++ b/sys/src/9/ip/arp.c
@@ -19,6 +19,8 @@ enum
 
 	AOK		= 1,
 	AWAIT		= 2,
+
+	MAXAGE_TIMER	= 15*60*1000,
 };
 
 char *arpstate[] =
@@ -182,7 +184,7 @@ arplookup(Arp *arp, Ipifc *ifc, uchar *ip)
  *  waiting for ip->mac to be resolved.
  */
 Arpent*
-arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)
+arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac, Routehint *rh)
 {
 	uchar v6ip[IPaddrlen];
 	Arpent *a;
@@ -191,15 +193,32 @@ arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)
 		v4tov6(v6ip, ip);
 		ip = v6ip;
 	}
+
+	if(rh != nil
+	&& (a = rh->a) != nil
+	&& a->state == AOK
+	&& a->ifc == ifc
+	&& a->ifcid == ifc->ifcid
+	&& ipcmp(ip, a->ip) == 0){
+		memmove(mac, a->mac, ifc->m->maclen);
+		a->utime = NOW;
+		if(a->utime - a->ctime < MAXAGE_TIMER)
+			return nil;
+	}
+
 	rlock(arp);
 	if((a = arplookup(arp, ifc, ip)) != nil && a->state == AOK){
 		memmove(mac, a->mac, ifc->m->maclen);
 		a->utime = NOW;
-		if(a->utime - a->ctime < 15*60*1000){
+		if(a->utime - a->ctime < MAXAGE_TIMER){
+			if(rh != nil)
+				rh->a = a;
 			runlock(arp);
 			return nil;
 		}
 	}
+	if(rh != nil)
+		rh->a = nil;
 	runlock(arp);
 	wlock(arp);
 	if((a = arplookup(arp, ifc, ip)) == nil)
@@ -269,11 +288,11 @@ arprelease(Arp *arp, Arpent*)
  * called with arp locked
  */
 Block*
-arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac)
+arpresolve(Arp *arp, Arpent *a, uchar *mac, Routehint *rh)
 {
 	Block *bp;
 
-	memmove(a->mac, mac, type->maclen);
+	memmove(a->mac, mac, a->ifc->m->maclen);
 	if(a->state == AWAIT) {
 		rxmtunchain(arp, a);
 		a->rxtsrem = 0;
@@ -282,6 +301,8 @@ arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac)
 	a->hold = a->last = nil;
 	a->ctime = a->utime = NOW;
 	a->state = AOK;
+	if(rh != nil)
+		rh->a = a;
 	wunlock(arp);
 
 	return bp;
@@ -290,6 +311,7 @@ arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac)
 int
 arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, uchar *ia, Ipifc *ifc, int refresh)
 {
+	Routehint rh;
 	uchar v6ip[IPaddrlen];
 	Block *bp, *next;
 	Arpent *a;
@@ -299,14 +321,16 @@ arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, uchar *ia, Ipifc *if
 	if(ifc->m == nil || ifc->m->maclen != n || ifc->m->maclen == 0)
 		return -1;
 
+	rh.r = nil;
+	rh.a = nil;
 	switch(version){
 	case V4:
-		r = v4lookup(fs, ip, ia, nil);
+		r = v4lookup(fs, ip, ia, &rh);
 		v4tov6(v6ip, ip);
 		ip = v6ip;
 		break;
 	case V6:
-		r = v6lookup(fs, ip, ia, nil);
+		r = v6lookup(fs, ip, ia, &rh);
 		break;
 	default:
 		panic("arpenter: version %d", version);
@@ -326,9 +350,9 @@ arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, uchar *ia, Ipifc *if
 		}
 		a = newarpent(arp, ip, ifc);
 	}
+	bp = arpresolve(arp, a, mac, &rh);	/* unlocks arp */
 	if(version == V4)
 		ip += IPv4off;
-	bp = arpresolve(arp, a, ifc->m, mac);	/* unlocks arp */
 	for(; bp != nil; bp = next){
 		next = bp->list;
 		bp->list = nil;
@@ -336,7 +360,7 @@ arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, uchar *ia, Ipifc *if
 			freeblistchain(next);
 			break;
 		}
-		ipifcoput(ifc, bp, version, ip);
+		ipifcoput(ifc, bp, version, ip, &rh);
 		poperror();
 	}
 	return 1;
@@ -496,8 +520,9 @@ arpread(Arp *arp, char *s, ulong offset, int len)
 }
 
 void
-ndpsendsol(Fs *f, Ipifc *ifc, Arpent *a)
+ndpsendsol(Fs *f, Arpent *a)
 {
+	Ipifc *ifc = a->ifc;
 	uchar targ[IPaddrlen], src[IPaddrlen];
 
 	if(a->rxtsrem == 0)
@@ -538,7 +563,7 @@ rxmt(Arp *arp)
 	while((a = arp->rxmt[0]) != nil && NOW - a->ctime > 3*RETRANS_TIMER/4){
 		if(a->rxtsrem > 0 && (ifc = a->ifc) != nil && canrlock(ifc)){
 			if(a->ifcid == ifc->ifcid){
-				ndpsendsol(arp->f, ifc, a);	/* unlocks arp */
+				ndpsendsol(arp->f, a);	/* unlocks arp */
 				runlock(ifc);
 
 				wlock(arp);