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

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).