kvm: improved performance on creating VM (#2923)

Improved performance on creating VM for KVM virtualization.

On a huge hosts every "ifconfig | grep" takes a lot of time (about 2.5-3 minutes on hosts with 500 machines). For example: ip link show dev $vlanDev > /dev/null is faster than ifconfig |grep -w $vlanDev > /dev/null. But using ip command is much better. Using this patch you can create 500s machine in 10 seconds. You don't need slow ifconfig prints anymore.

Author: alexanderbazhenoff

scripts/vm/network/vnet/modifyvlan.sh

@@ -48,11 +48,7 @@ addVlan() {
 	fi
 
 	# is up?
-  	ifconfig |grep -w $vlanDev > /dev/null
-	if [ $? -gt 0 ]
-	then
-		ifconfig $vlanDev up > /dev/null
-	fi
+	ip link set $vlanDev up > /dev/null 2>/dev/null
 
 	if [ ! -d /sys/class/net/$vlanBr ]
 	then
@@ -86,11 +82,7 @@ addVlan() {
 		fi
 	fi
 	# is vlanBr up?
-	ifconfig |grep -w $vlanBr > /dev/null
-	if [ $? -gt 0 ]
-	then
-		ifconfig $vlanBr up
-	fi
+	ip link set $vlanBr up > /dev/null 2>/dev/null
 
 	return 0
 }
@@ -109,7 +101,7 @@ deleteVlan() {
 		return 1
 	fi	
 
-	ifconfig $vlanBr down
+	ip link set $vlanBr down
 
 	if [ $? -gt 0 ]
 	then