Small tangent. Would you mind sharing how you calculate CPI? Do you just do timing and use some base clock rate? With the CPU frequency being so variable (with boost clocks) I imagine the correct way is with some fancy instrumentation.
Perhaps cachegrind or linux perf? CPU frequency being variable is not an issue because you can disable turbo boost and limit the frequency to something that the CPU will not throttle. You can also pin the core with taskset to avoid migration. cset shield can prevent the CPU from executing other tasks for latency measurement (although you will still experience some jitter due to interrupts).
