Comment 16 for bug 1188647

For the decision to re-enable the intel pstate driver by default or not, the suggestion is to be cautious. The driver keeps changing in rather fundamental ways, such that one can never be sure how it is going to perform. I will attach two graphs to (hopefully) help make my point.

The first graph demonstrates a dramatic difference in CPU frequency scaling response as a function of load between kernel 3.12 and 3.15RC2 at a fixed idle (sleep) / work frequency.

The second graph (to be posted in a moment) demonstrates a dramatic difference in CPU scaling frequency as a function of idle (sleep) /work frequency at a fixed load.

Don't get me wrong here, as I am a proponent of the intel_pstate driver, but I am concerned about how its response to stimulus keeps changing.