Simple cpu limiting example.

examples/cpu.py

@@ -0,0 +1,81 @@
+#!/usr/bin/python
+
+"""
+cpu.py: test iperf bandwidth for varying cpu limtis
+"""
+
+from mininet.net import Mininet
+from mininet.node import CPULimitedHost
+from mininet.topolib import TreeTopo
+from mininet.util import custom
+from mininet.log import setLogLevel, output
+
+from time import sleep
+
+def waitListening(client, server, port):
+    "Wait until server is listening on port"
+    if not client.cmd('which telnet'):
+        raise Exception('Could not find telnet')
+    cmd = ('sh -c "echo A | telnet -e A %s %s"' %
+           (server.IP(), port))
+    while 'Connected' not in client.cmd(cmd):
+        output('waiting for', server,
+               'to listen on port', port, '\n')
+        sleep(.5)
+
+
+def bwtest( cpuLimits, period_us=10000, seconds=5 ):
+    """Example/test of link and CPU bandwidth limits
+       cpu: cpu limit as fraction of overall CPU time"""
+
+    topo = TreeTopo( depth=1, fanout=2 )
+
+    results = {}
+
+    for sched in 'rt', 'cfs':
+        print '*** Testing with', sched, 'bandwidth limiting'
+        for cpu in cpuLimits:
+            host = custom( CPULimitedHost, sched=sched,
+                           period_us=period_us,
+                           cpu=cpu )
+            net = Mininet( topo=topo, host=host )
+            net.start()
+            net.pingAll()
+            hosts = [ net.getNodeByName( h ) for h in topo.hosts() ]
+            client, server = hosts[ 0 ], hosts[ -1 ]
+            server.cmd( 'iperf -s -p 5001 &' )
+            waitListening( client, server, 5001 )
+            result = client.cmd( 'iperf -yc -t %s -c %s' % (
+                    seconds, server.IP() ) ).split( ',' )
+            bps = float( result[ -1 ] )
+            server.cmdPrint( 'kill %iperf' )
+            net.stop()
+            updated = results.get( sched, [] )
+            updated += [ ( cpu, bps ) ]
+            results[ sched ] = updated
+
+    return results
+
+
+def dump( results ):
+    "Dump results"
+
+    format = '%s\t%s\t%s'
+
+    print
+    print format % ( 'sched', 'cpu', 'client MB/s' )
+    print
+
+    for sched in sorted( results.keys() ):
+        entries = results[ sched ]
+        for cpu, bps in entries:
+            pct = '%.2f%%' % ( cpu * 100 )
+            mbps = bps / 1e6
+            print format % ( sched, pct, mbps )
+
+
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    limits = [ .4, .3, .2, .1 ]
+    results = bwtest( limits )
+    dump( results )