perf rapl/powercap : powercap has more lenient permissions

[Vince Weaver]

Hello

so perf_event requires paranoid value of 0 to read the RAPL counters

	perf stat -a -e power/energy-cores/ /bin/ls
Error:
You may not have permission to collect system-wide stats.

But I can use the new powercap driver to read the same values no problem:

	cat /sys/devices/virtual/powercap/intel-rapl/intel-rapl:0/intel-rapl:0:0/energy_uj
121384969344


Is this expected?  Should the powercap permissions be locked down more?	


Just hitting this, as PAPI has at least 4 different interfaces to read the 
RAPL power values (perf_event, /dev/msr, libmsr, powercap).  Five if you 
count that AMD exports their equivelent info via the hwmon interface.

Vince