主机类

包括 Host 和 CPULimitedHost 两个类。

mininet.node.Host

表示一个主机节点，目前跟 Node 类定义相同。
在主机类上执行命令可以通过 Cmd() 或者 sendCmd() 方法，前者会等待命令的输出结果，后者会直接返回，并允许使用后续的 monitor() 来进行监视跟踪。

mininet.node.CPULimitedHost

继承自 Host 类，通过 cgroup 工具来对 CPU 进行限制。

init

  1. def __init__( self, name, sched='cfs', **kwargs ):
  2.         Host.__init__( self, name, **kwargs )
  3.         # Initialize class if necessary
  4.         if not CPULimitedHost.inited:
  5.             CPULimitedHost.init()
  6.         # Create a cgroup and move shell into it
  7.         self.cgroup = 'cpu,cpuacct,cpuset:/' + self.name
  8.         errFail( 'cgcreate -g ' + self.cgroup )
  9.         # We don't add ourselves to a cpuset because you must
  10.         # specify the cpu and memory placement first
  11.         errFail( 'cgclassify -g cpu,cpuacct:/%s %s' % ( self.name, self.pid ) )
  12.         # BL: Setting the correct period/quota is tricky, particularly
  13.         # for RT. RT allows very small quotas, but the overhead
  14.         # seems to be high. CFS has a mininimum quota of 1 ms, but
  15.         # still does better with larger period values.
  16.         self.period_us = kwargs.get( 'period_us', 100000 )
  17.         self.sched = sched
  18.         self.rtprio = 20