Performance Overhead Results for PAPI

These are generally measured with the "papi_cost" tool that
comes with PAPI, optionally with the included patch applied that
bins into percentiles.

This is the data used in Yan Liu's masters thesis
	Optimizing PAPI for Low-Overhead Counter Measurement

Also the 2017 Extreme-Scale Programming Tools Workshop Paper
	Enhancing PAPI with Low-Overhead rdpmc Reads

For more info see:
	http://web.eece.maine.edu/~vweaver/projects/papi-rdpmc/