introduce mitigation for the calling of an interfaces start routine.

decent drivers prefer to have a lot of packets on the send queue so they
can queue a lot of them up on the tx ring and then post them all in one
big chunk. unfortunately our stack queues one packet onto the send queue
and then calls the start handler immediately.

this mitigates against that queue, send, queue, send behaviour by trying to
call the start routine only once per softnet. now its queue, queue, queue,
send.

this is the result of a lot of discussion with claudio@
tested by many.

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/net/if.h b/sys/net/if.h
index c2adb9e9a36..21dc8f31e4f 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.h,v 1.93 2007/11/18 12:51:48 mpf Exp $	*/
+/*	$OpenBSD: if.h,v 1.94 2008/04/10 23:15:45 dlg Exp $	*/
 /*	$NetBSD: if.h,v 1.23 1996/05/07 02:40:27 thorpej Exp $	*/
 
 /*
@@ -178,6 +178,7 @@ TAILQ_HEAD(ifnet_head, ifnet);		/* the actual queue head */
 struct ifnet {				/* and the entries */
 	void	*if_softc;		/* lower-level data for this if */
 	TAILQ_ENTRY(ifnet) if_list;	/* all struct ifnets are chained */
+	TAILQ_ENTRY(ifnet) if_txlist;	/* list of ifnets ready to tx */
 	TAILQ_HEAD(, ifaddr) if_addrlist; /* linked list of addresses per if */
 	TAILQ_HEAD(, ifg_list) if_groups; /* linked list of groups per if */
 	struct hook_desc_head *if_addrhooks; /* address change callbacks */
@@ -198,6 +199,7 @@ struct ifnet {				/* and the entries */
 	u_short	if_index;		/* numeric abbreviation for this if */
 	short	if_timer;		/* time 'til if_watchdog called */
 	short	if_flags;		/* up/down, broadcast, etc. */
+	int	if_xflags;		/* extra softnet flags */
 	struct	if_data if_data;	/* stats and other data about if */
 	u_int32_t if_hardmtu;		/* maximum MTU device supports */
 	int	if_capabilities;	/* interface capabilities */
@@ -265,6 +267,8 @@ struct ifnet {				/* and the entries */
 	(IFF_BROADCAST|IFF_POINTOPOINT|IFF_RUNNING|IFF_OACTIVE|\
 	    IFF_SIMPLEX|IFF_MULTICAST|IFF_ALLMULTI)
 
+#define IFXF_TXREADY	0x1		/* interface is ready to tx */
+
 /*
  * Some convenience macros used for setting ifi_baudrate.
  */
@@ -775,6 +779,7 @@ int	if_addgroup(struct ifnet *, const char *);
 int	if_delgroup(struct ifnet *, const char *);
 void	if_group_routechange(struct sockaddr *, struct sockaddr *);
 struct	ifnet *ifunit(const char *);
+void	if_start(struct ifnet *);
 
 struct	ifaddr *ifa_ifwithaddr(struct sockaddr *);
 struct	ifaddr *ifa_ifwithaf(int);