2.3.1b4 (#1184)

Including changes to mnexec -c to reduce the number of
close() system calls, which may help with performance in
containers on Ubuntu 22.04.

Note that systemd-udevd also seems to be a cause of performance issues
and should probably be disabled while running Mininet.

Adding dbeug logging to test_simpleperf because it is failing
intermittently. (Note with packet loss it can fail, but this
is not how we should be testing it.)

examples/test/test_simpleperf.py

@@ -19,9 +19,12 @@ class testSimplePerf( unittest.TestCase ):
         # 10 Mb/s, plus or minus 20% tolerance
         BW = 10
         TOLERANCE = .2
-        p = pexpect.spawn( 'python -m mininet.examples.simpleperf testmode' )
+        p = pexpect.spawn(
+            'python -m mininet.examples.simpleperf testmode' )
+        # Log since this seems to be failing intermittently
+        p.logfile = sys.stdout
         # check iperf results
-        p.expect( "Results: \['10M', '([\d\.]+) .bits/sec", timeout=480 )
+        p.expect( "Results: \['10M', '([\d\.]+) .bits/sec", timeout=90 )
         measuredBw = float( p.match.group( 1 ) )
         lowerBound = BW * ( 1 - TOLERANCE )
         upperBound = BW + ( 1 + TOLERANCE )
@@ -30,5 +33,5 @@ class testSimplePerf( unittest.TestCase ):
         p.wait()
 
 if __name__ == '__main__':
-    setLogLevel( 'warning' )
+    setLogLevel( 'debug' )
     unittest.main()