Class CustomMachineConfiguration

deps/v8/tools/run_perf.py:1046–1148

class CustomMachineConfiguration:
  def __init__(self, disable_aslr = False, governor = None):
    self.aslr_backup = None
    self.governor_backup = None
    self.disable_aslr = disable_aslr
    self.governor = governor

  def __enter__(self):
    if self.disable_aslr:
      self.aslr_backup = CustomMachineConfiguration.GetASLR()
      CustomMachineConfiguration.SetASLR(0)
    if self.governor is not None:
      self.governor_backup = CustomMachineConfiguration.GetCPUGovernor()
      CustomMachineConfiguration.SetCPUGovernor(self.governor)
    return self

  def __exit__(self, type, value, traceback):
    if self.aslr_backup is not None:
      CustomMachineConfiguration.SetASLR(self.aslr_backup)
    if self.governor_backup is not None:
      CustomMachineConfiguration.SetCPUGovernor(self.governor_backup)

  @staticmethod
  def GetASLR():
    try:
      with open('/proc/sys/kernel/randomize_va_space', 'r') as f:
        return int(f.readline().strip())
    except Exception:
      logging.exception('Failed to get current ASLR settings.')
      raise

  @staticmethod
  def SetASLR(value):
    try:
      with open('/proc/sys/kernel/randomize_va_space', 'w') as f:
        f.write(str(value))
    except Exception:
      logging.exception(
          'Failed to update ASLR to %s. Are we running under sudo?', value)
      raise

    new_value = CustomMachineConfiguration.GetASLR()
    if value != new_value:
      raise Exception('Present value is %s' % new_value)

  @staticmethod
  def GetCPUCoresRange():
    try:
      with open('/sys/devices/system/cpu/present', 'r') as f:
        indexes = f.readline()
        r = list(map(int, indexes.split('-')))
        if len(r) == 1:
          return list(range(r[0], r[0] + 1))
        return list(range(r[0], r[1] + 1))
    except Exception:
      logging.exception('Failed to retrieve number of CPUs.')
      raise