40COL
%c%RAPL Measurement Accuracy

* Intel Documentation indicates Energy
  readings are updated roughly every 
  millisecond (1kHz)

* The hardware also reports measurement
  quanta. This can vary among processor
  releases. On our Sandybridge EP all 
  Energy measurements are in multiples 
  of 15.2nJ

* Power and Energy can vary between 
  identical packages on a system, 
  even when running identical workloads.  
  It is unclear whether this is due to 
  process variation or else calibration

