Reduce interface move delay and make configurable

Much faster now; from 1 s delay to 100 us.

mininet/mininet.py

@@ -333,6 +333,8 @@ class Switch( Node ):
 # live in the root namespace and thus do not have to be
 # explicitly moved.
 
+MOVEINTF_DELAY = 0.0001
+
 def makeIntfPair( intf1, intf2 ):
    "Make a veth pair of intf1 and intf2."
    # Delete any old interfaces with the same names
@@ -353,11 +355,11 @@ def moveIntf( intf, node ):
       return False
    return True
 
-def retry( n, fn, *args):
+def retry( n, retry_delay, fn, *args):
    "Try something N times before giving up."
    tries = 0
    while not apply( fn, args ) and tries < n:
-      sleep( 1 )
+      sleep( retry_delay )
       print "*** retrying..."; flush()
       tries += 1
    if tries >= n: 
@@ -369,8 +371,8 @@ def createLink( node1, node2 ):
    intf1 = node1.newIntf()
    intf2 = node2.newIntf()
    makeIntfPair( intf1, intf2 )
-   if node1.inNamespace: retry( 3, moveIntf, intf1, node1 )
-   if node2.inNamespace: retry( 3, moveIntf, intf2, node2 )
+   if node1.inNamespace: retry( 3, MOVEINTF_DELAY, moveIntf, intf1, node1 )
+   if node2.inNamespace: retry( 3, MOVEINTF_DELAY, moveIntf, intf2, node2 )
    node1.connection[ intf1 ] = ( node2, intf2 )
    node2.connection[ intf2 ] = ( node1, intf1 )
    return intf1, intf2