Increase link delay to 2ms for more robust effect

With a 1 ms delay, the performance tests periodically fails
under nested virtualization, which is how we are testing it.
Increasing the delay should make the effect (lower TCP
data rates as latency increases, due to TCP's congestion
control algorithm) more pronounced and robust.

Conflicts:
	examples/linearbandwidth.py

examples/linearbandwidth.py

@@ -26,7 +26,7 @@
 from mininet.net import Mininet
 from mininet.node import UserSwitch, OVSKernelSwitch, Controller
 from mininet.topo import Topo
-from mininet.log import lg
+from mininet.log import lg, info
 from mininet.util import irange, quietRun
 from mininet.link import TCLink
 from functools import partial
@@ -86,7 +86,7 @@ def linearBandwidthTest( lengths ):
         print "*** testing", datapath, "datapath"
         Switch = switches[ datapath ]
         results[ datapath ] = []
-        link = partial( TCLink, delay='1ms' )
+        link = partial( TCLink, delay='2ms' )
         net = Mininet( topo=topo, switch=Switch,
                        controller=Controller, waitConnected=True,
                        link=link )
@@ -100,11 +100,12 @@ def linearBandwidthTest( lengths ):
             # Try to prime the pump to reduce PACKET_INs during test
             # since the reference controller is reactive
             src.cmd( 'telnet', dst.IP(), '5001' )
-            print "testing", src.name, "<->", dst.name,
-            bandwidth = net.iperf( [ src, dst ], seconds=10 )
-            print bandwidth
+            info( "testing", src.name, "<->", dst.name, '\n' )
+            # serverbw = received; _clientbw = buffered
+            serverbw, _clientbw = net.iperf( [ src, dst ], seconds=10 )
+            info( serverbw, '\n' )
             flush()
-            results[ datapath ] += [ ( n, bandwidth ) ]
+            results[ datapath ] += [ ( n, serverbw ) ]
         net.stop()
 
     for datapath in switches.keys():
@@ -112,12 +113,13 @@ def linearBandwidthTest( lengths ):
         print "*** Linear network results for", datapath, "datapath:"
         print
         result = results[ datapath ]
-        print "SwitchCount\tiperf Results"
-        for switchCount, bandwidth in result:
-            print switchCount, '\t\t',
-            print bandwidth[ 0 ], 'server, ', bandwidth[ 1 ], 'client'
-        print
-    print
+        info( "SwitchCount\tiperf Results\n" )
+        for switchCount, serverbw in result:
+            info( switchCount, '\t\t' )
+            info( serverbw, '\n' )
+        info( '\n')
+    info( '\n' )
+
 
 if __name__ == '__main__':
     lg.setLogLevel( 'info' )

examples/test/test_linearbandwidth.py

@@ -34,8 +34,8 @@ def testLinearBandwidth( self ):
                     bw *= 10 ** 9
                 # check that we have a previous result to compare to
                 if n != 1:
-                    info = ( 'bw: %d bits/s across %d switches, '
-                             'previous: %d bits/s across %d switches' %
+                    info = ( 'bw: %.2e bits/s across %d switches, '
+                             'previous: %.2e bits/s across %d switches' %
                              ( bw, n, previous_bw, previous_n ) )
                     self.assertTrue( bw < previous_bw, info )
                 previous_bw, previous_n = bw, n