code: public double getElapsedTimeLastThread(int from, int to) {
  	   Accumulator acc = lastAccumulator.get();
  	   
  	   return acc == null ? Double.NaN : (acc.currentTimes[to] - acc.currentTimes[from]) / MILLION;
     }
docs: Elapsed time for all events {@code from} through {@code to} for the last thread that executed this KernelDeviceProfile
  instance respective kernel and device.
  
  @param from the first event to consider that defines the elapsed period start
  @param to the last event to consider for elapsed period