lantz
f0c726a42f
This helps with virtualenv although it can open up another security hole if you end up using an unexpected python interpreter. Overall it seems to make sense to err on the side of usability but it's good to be aware of security. However, for the remaining utility scripts that require python 2, we explicitly note this with #!/usr/bin/python2.
108 lines
3.8 KiB
Python
Executable File
108 lines
3.8 KiB
Python
Executable File
#!/usr/bin/env python
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"""
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cpu.py: test iperf bandwidth for varying cpu limits
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Since we are limiting the hosts (only), we should expect the iperf
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processes to be affected, as well as any system processing which is
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billed to the hosts.
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We reserve >50% of cycles for system processing; we assume that
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this is enough for it not to affect results. Hosts are limited to
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40% of total cycles, which we assume is enough to make them CPU
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bound.
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As CPU performance increases over time, we may have to reduce the
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overall CPU allocation so that the host processing is still CPU bound.
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This is perhaps an argument for specifying performance in a more
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system-independent manner.
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It would also be nice to have a better handle on limiting packet
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processing cycles. It's not entirely clear to me how those are
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billed to user or system processes if we are using OVS with a kernel
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datapath. With a user datapath, they are easier to account for, but
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overall performance is usually lower.
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Although the iperf client uses more CPU and should be CPU bound (?),
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we measure the received data at the server since the client transmit
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rate includes buffering.
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"""
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from mininet.net import Mininet
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from mininet.node import CPULimitedHost
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from mininet.topolib import TreeTopo
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from mininet.util import custom, waitListening, decode
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from mininet.log import setLogLevel, info
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from mininet.clean import cleanup
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def bwtest( cpuLimits, period_us=100000, seconds=10 ):
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"""Example/test of link and CPU bandwidth limits
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cpu: cpu limit as fraction of overall CPU time"""
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topo = TreeTopo( depth=1, fanout=2 )
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results = {}
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for sched in 'rt', 'cfs':
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info( '*** Testing with', sched, 'bandwidth limiting\n' )
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for cpu in cpuLimits:
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# cpu is the cpu fraction for all hosts, so we divide
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# it across two hosts
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host = custom( CPULimitedHost, sched=sched,
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period_us=period_us,
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cpu=.5*cpu )
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try:
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net = Mininet( topo=topo, host=host, waitConnected=True )
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# pylint: disable=bare-except
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except: # noqa
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info( '*** Skipping scheduler %s and cleaning up\n' % sched )
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cleanup()
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break
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net.start()
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net.pingAll()
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hosts = [ net.getNodeByName( h ) for h in topo.hosts() ]
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client, server = hosts[ 0 ], hosts[ -1 ]
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info( '*** Starting iperf with %d%% of CPU allocated to hosts\n' %
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( 100.0 * cpu ) )
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# We measure at the server because it doesn't include
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# the client's buffer fill rate
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popen = server.popen( 'iperf -yc -s -p 5001' )
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waitListening( client, server, 5001 )
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# ignore empty result from waitListening/telnet
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popen.stdout.readline()
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client.cmd( 'iperf -yc -t %s -c %s' % ( seconds, server.IP() ) )
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result = decode( popen.stdout.readline() ).split( ',' )
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bps = float( result[ -1 ] )
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popen.terminate()
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net.stop()
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updated = results.get( sched, [] )
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updated += [ ( cpu, bps ) ]
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results[ sched ] = updated
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return results
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def dump( results ):
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"Dump results"
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fmt = '%s\t%s\t%s\n'
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info( '\n' )
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info( fmt % ( 'sched', 'cpu', 'received bits/sec' ) )
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for sched in sorted( results.keys() ):
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entries = results[ sched ]
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for cpu, bps in entries:
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pct = '%d%%' % ( cpu * 100 )
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mbps = '%.2e' % bps
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info( fmt % ( sched, pct, mbps ) )
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if __name__ == '__main__':
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setLogLevel( 'info' )
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# These are the limits for the hosts/iperfs - the
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# rest is for system processes
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limits = [ .5, .4, .3, .2, .1 ]
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out = bwtest( limits )
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dump( out )
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