Improved connection establishment performance by doing local port lookups via

a hashed port list. In the new scheme, in_pcblookup() goes away and is
replaced by a new routine, in_pcblookup_local() for doing the local port
check. Note that this implementation is space inefficient in that the PCB
struct is now too large to fit into 128 bytes. I might deal with this in the
future by using the new zone allocator, but I wanted these changes to be
extensively tested in their current form first.

Also:
1) Fixed off-by-one errors in the port lookup loops in in_pcbbind().
2) Got rid of some unneeded rehashing. Adding a new routine, in_pcbinshash()
   to do the initialial hash insertion.
3) Renamed in_pcblookuphash() to in_pcblookup_hash() for easier readability.
4) Added a new routine, in_pcbremlists() to remove the PCB from the various
   hash lists.
5) Added/deleted comments where appropriate.
6) Removed unnecessary splnet() locking. In general, the PCB functions should
   be called at splnet()...there are unfortunately a few exceptions, however.
7) Reorganized a few structs for better cache line behavior.
8) Killed my TCP_ACK_HACK kludge. It may come back in a different form in
   the future, however.

These changes have been tested on wcarchive for more than a month. In tests
done here, connection establishment overhead is reduced by more than 50
times, thus getting rid of one of the major networking scalability problems.

Still to do: make tcp_fastimo/tcp_slowtimo scale well for systems with a
large number of connections. tcp_fastimo is easy; tcp_slowtimo is difficult.

WARNING: Anything that knows about inpcb and tcpcb structs will have to be
         recompiled; at the very least, this includes netstat(1).

1 files changed, 4 insertions, 3 deletions

diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c
index 91981c1..773e42d 100644
--- a/sys/netinet/udp_usrreq.c
+++ b/sys/netinet/udp_usrreq.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)udp_usrreq.c	8.6 (Berkeley) 5/23/95
- *	$Id: udp_usrreq.c,v 1.42 1997/12/19 23:46:21 bde Exp $
+ *	$Id: udp_usrreq.c,v 1.43 1998/01/25 17:25:41 steve Exp $
  */
 
 #include <sys/param.h>
@@ -78,7 +78,7 @@ static struct	inpcbhead udb;		/* from udp_var.h */
 static struct	inpcbinfo udbinfo;
 
 #ifndef UDBHASHSIZE
-#define UDBHASHSIZE 64
+#define UDBHASHSIZE 16
 #endif
 
 static struct	udpstat udpstat;	/* from udp_var.h */
@@ -97,6 +97,7 @@ udp_init()
 	LIST_INIT(&udb);
 	udbinfo.listhead = &udb;
 	udbinfo.hashbase = hashinit(UDBHASHSIZE, M_PCB, &udbinfo.hashmask);
+	udbinfo.porthashbase = hashinit(UDBHASHSIZE, M_PCB, &udbinfo.porthashmask);
 }
 
 void
@@ -274,7 +275,7 @@ udp_input(m, iphlen)
 	/*
 	 * Locate pcb for datagram.
 	 */
-	inp = in_pcblookuphash(&udbinfo, ip->ip_src, uh->uh_sport,
+	inp = in_pcblookup_hash(&udbinfo, ip->ip_src, uh->uh_sport,
 	    ip->ip_dst, uh->uh_dport, 1);
 	if (inp == NULL) {
 		if (log_in_vain) {