Added simpleperf.py to examples.

examples/README

@@ -54,6 +54,10 @@ These two examples demonstrate how to create a network by using the lowest-
 level Mininet functions. Generally the higher-level API is easier to use,
 but scratchnet shows what is going on behind the scenes.
 
+simpleperf.py:
+
+A simple example of configuring network and CPU bandwidth limits.
+
 sshd.py:
 
 This example shows how to run an sshd process in each host, allowing

examples/simpleperf.py

@@ -0,0 +1,45 @@
+#!/usr/bin/python
+
+"""
+Simple example of setting network and CPU parameters
+"""
+
+from mininet.topo import Topo
+from mininet.net import Mininet
+from mininet.node import CPULimitedHost
+from mininet.link import TCLink
+from mininet.util import dumpNodeConnections
+from mininet.log import setLogLevel
+
+class SingleSwitchTopo(Topo):
+   "Single switch connected to n hosts."
+   def __init__(self, n=2, **opts):
+       Topo.__init__(self, **opts)
+       switch = self.add_switch('s1')
+       for h in range(n+1):
+        # Each host gets 50%/n of system CPU
+           host = self.add_host('h%s' % (h + 1),
+            cpu=.5/n)
+        # 10 Mbps, 5ms delay, 10% loss
+           self.add_link(host, switch,
+            bw=10, delay='5ms', loss=10, use_htb=True)
+
+def perfTest():
+   "Create network and run simple performance test"
+   topo = SingleSwitchTopo(n=4)
+   net = Mininet(topo=topo,
+                 host=CPULimitedHost, link=TCLink)
+   net.start()
+   print "Dumping host connections"
+   dumpNodeConnections(net.hosts)
+   print "Testing network connectivity"
+   net.pingAll()
+   print "Testing bandwidth between h1 and h4"
+   h1 = net.getNodeByName('h1')
+   h4 = net.getNodeByName('h4')
+   net.iperf((h1, h4))
+   net.stop()
+
+if __name__ == '__main__':
+   setLogLevel('info')
+   perfTest()