code: def _set_process_priority(self):
          
  
          if self._process_priority == "normal":
              return
  
          if sys.platform.startswith("win"):
              try:
                  import win32api
                  import win32con
                  import win32process
              except ImportError:
                  log.error("pywin32 must be installed to change the priority class for QEMU VM {}".format(self._name))
              else:
                  log.info("Setting QEMU VM {} priority class to {}".format(self._name, self._process_priority))
                  handle = win32api.OpenProcess(win32con.PROCESS_ALL_ACCESS, 0, self._process.pid)
                  if self._process_priority == "realtime":
                      priority = win32process.REALTIME_PRIORITY_CLASS
                  elif self._process_priority == "very high":
                      priority = win32process.HIGH_PRIORITY_CLASS
                  elif self._process_priority == "high":
                      priority = win32process.ABOVE_NORMAL_PRIORITY_CLASS
                  elif self._process_priority == "low":
                      priority = win32process.BELOW_NORMAL_PRIORITY_CLASS
                  elif self._process_priority == "very low":
                      priority = win32process.IDLE_PRIORITY_CLASS
                  else:
                      priority = win32process.NORMAL_PRIORITY_CLASS
                  try:
                      win32process.SetPriorityClass(handle, priority)
                  except win32process.error as e:
                      log.error('Could not change process priority for QEMU VM "{}": {}'.format(self._name, e))
          else:
              if self._process_priority == "realtime":
                  priority = -20
              elif self._process_priority == "very high":
                  priority = -15
              elif self._process_priority == "high":
                  priority = -5
              elif self._process_priority == "low":
                  priority = 5
              elif self._process_priority == "very low":
                  priority = 19
              else:
                  priority = 0
              try:
                  process = yield from asyncio.create_subprocess_exec('renice', '-n', str(priority), '-p', str(self._process.pid))
                  yield from process.wait()
              except (OSError, subprocess.SubprocessError) as e:
                  log.error('Could not change process priority for QEMU VM "{}": {}'.format(self._name, e))
docs: Changes the process priority