I think it is a well put together analysis, but I feel I'm missing something.

> FreeCache and GroupCache reads are not lock-free and don’t scale after a point (20 concurrent accesses). (lower value is better on y axis)

If you look at the graphs, they level out and seem to work best with more concurrent load, the exact opposite of what they say. Am I missing something?

Also, I think it would be valuable to see higher concurrent requests: with what I'm used to, 60 concurrent requests would be low - I'm interested in maybe 1-5k concurrent requests.