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%c%RAPL PAPI Interface

* Access to RAPL data requires reading
  a CPU MSR register.  
  This requires OS support

* Linux currently has no driver and 
  likely won't for the near future

* Linux does support an 'MSR' driver.  
  Given proper read permissions, MSRs 
  can be accessed via /dev/cpu/*/msr

* PAPI uses the 'MSR' driver to gather 
  RAPL values