The linked PDF in the post contains a section on how the values are measured and a link to the test suite. Search in [1] for "How the values were measured". For another project that measures the same/very similar values you can check out [2]. They have a paper about the tool they are using [3].
There is also AMD's "Software Optimization Guide" that might contain some background information. [4] has many direct attachments, AMD tends to break direct links. Intel should have similar docs, but I am currently more focused on AMD, so I only have those links at hand.
