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.

examples/linearbandwidth.py

@@ -87,7 +87,7 @@ def linearBandwidthTest( lengths ):
         info( "*** testing", datapath, "datapath\n" )
         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 )
@@ -102,19 +102,20 @@ def linearBandwidthTest( lengths ):
             # since the reference controller is reactive
             src.cmd( 'telnet', dst.IP(), '5001' )
             info( "testing", src.name, "<->", dst.name, '\n' )
-            bandwidth = net.iperf( [ src, dst ], seconds=10 )
-            info( bandwidth, '\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():
         info( "\n*** Linear network results for", datapath, "datapath:\n" )
         result = results[ datapath ]
         info( "SwitchCount\tiperf Results\n" )
-        for switchCount, bandwidth in result:
+        for switchCount, serverbw in result:
             info( switchCount, '\t\t' )
-            info( bandwidth[ 0 ], 'server, ', bandwidth[ 1 ], 'client\n' )
+            info( serverbw, '\n' )
         info( '\n')
     info( '\n' )
 

examples/test/test_linearbandwidth.py

@@ -34,8 +34,8 @@ class testLinearBandwidth( unittest.TestCase ):
                     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