text: 
  module.exports = function(pmx) {
    var TIME_INTERVAL = 1000;
  
    var oldTime = process.hrtime();
  
    var histogram = pmx.probe().histogram({
      name        : 'Loop delay',
      measurement : 'mean',
      unit        : 'ms'
    });
  
    var pace_interval = setInterval(function() {
      var newTime = process.hrtime();
      var delay = (newTime[0] - oldTime[0]) * 1e3 + (newTime[1] - oldTime[1]) / 1e6 - TIME_INTERVAL;
      oldTime = newTime;
      histogram.update(delay);
    }, TIME_INTERVAL);
  
    pace_interval.unref();
  
    // Clear pacemaker interval cooking on SIGINT (first PM2 signal when killing);
    process.on('SIGINT', function stopIntervalSIGINT() {
      clearInterval(pace_interval);
    });
  
  };
  