--- if_em.c-1.44.2.3.orig	Tue Nov  9 05:06:14 2004
+++ if_em.c	Fri Nov 19 19:01:11 2004
@@ -182,6 +182,9 @@ static int  em_sysctl_int_delay(SYSCTL_H
 static void em_add_int_delay_sysctl(struct adapter *, const char *,
 				    const char *, struct em_int_delay_info *,
 				    int, int);
+#if 1
+static int em_sysctl_throttle_valve(SYSCTL_HANDLER_ARGS);
+#endif
 
 /*********************************************************************
  *  FreeBSD Device Interface Entry Points                    
@@ -358,6 +361,13 @@ em_attach(device_t dev)
 		    &adapter->tx_abs_int_delay,
 		    E1000_REG_OFFSET(&adapter->hw, TADV),
 		    em_tx_abs_int_delay_dflt);
+#if 1
+		SYSCTL_ADD_PROC(&adapter->sysctl_ctx,
+		    SYSCTL_CHILDREN(adapter->sysctl_tree), OID_AUTO,
+		    "int_throttle_valve", CTLTYPE_INT|CTLFLAG_RW,
+		    adapter, 0, em_sysctl_throttle_valve, "IU",
+		    "interrupt throttling rate");
+#endif
 	}
       
 	/* Parameters (to be read from user) */   
@@ -403,6 +413,10 @@ em_attach(device_t dev)
 	 */
 	adapter->hw.report_tx_early = 1;
 
+#if 1
+#define MAX_INTS_PER_SEC        8000
+	adapter->throttle_valve = MAX_INTS_PER_SEC;
+#endif
 
 	if (em_allocate_pci_resources(adapter)) {
 		printf("em%d: Allocation of PCI resources failed\n", 
@@ -2608,12 +2622,16 @@ em_initialize_receive_unit(struct adapte
 	if(adapter->hw.mac_type >= em_82540) {
 		E1000_WRITE_REG(&adapter->hw, RADV,
 		    adapter->rx_abs_int_delay.value);
-
+#if 1
+                E1000_WRITE_REG(&adapter->hw, ITR,
+		    1000000000 / (adapter->throttle_valve * 256));
+#else
                 /* Set the interrupt throttling rate.  Value is calculated
                  * as DEFAULT_ITR = 1/(MAX_INTS_PER_SEC * 256ns) */
 #define MAX_INTS_PER_SEC        8000
 #define DEFAULT_ITR             1000000000/(MAX_INTS_PER_SEC * 256)
                 E1000_WRITE_REG(&adapter->hw, ITR, DEFAULT_ITR);
+#endif
         }       
 
 	/* Setup the Base and Length of the Rx Descriptor Ring */
@@ -3383,4 +3401,35 @@ em_add_int_delay_sysctl(struct adapter *
 	    SYSCTL_CHILDREN(adapter->sysctl_tree),
 	    OID_AUTO, name, CTLTYPE_INT|CTLFLAG_RW,
 	    info, 0, em_sysctl_int_delay, "I", description);
+}
+
+static int
+em_sysctl_throttle_valve(SYSCTL_HANDLER_ARGS)
+{
+	struct adapter *adapter;
+	int error;
+	u_int32_t valve;
+	int s;
+	int value;
+
+	adapter = (struct adapter *)arg1;
+	valve =  adapter->throttle_valve;
+	error = sysctl_handle_int(oidp, &valve, 0, req);
+	if (error != 0 || req->newptr == NULL)
+		return error;
+	adapter->throttle_valve = valve;
+	
+	s = splimp();
+
+	/* Set the interrupt throttling rate.  Value is calculated
+	 * as ITR = 1/(INTS_PER_SEC * 256ns) */
+	if(valve > 0)
+		value = 1000000000/(valve * 256);
+	else
+		value = 0;
+	E1000_WRITE_REG(&adapter->hw, ITR, value);
+
+	splx(s);
+
+	return 0;
 }
--- if_em.h-1.25.2.1.orig	Fri Nov 19 19:00:03 2004
+++ if_em.h	Fri Nov 19 18:18:57 2004
@@ -353,6 +353,9 @@
 	u_int16_t       link_speed;
 	u_int16_t       link_duplex;
 	u_int32_t       smartspeed;
+#if 1
+	u_int32_t	throttle_valve;
+#endif
 	struct em_int_delay_info tx_int_delay;
 	struct em_int_delay_info tx_abs_int_delay;
 	struct em_int_delay_info rx_int_delay;