CPU fun
Who really designed this processor?
Introduction
This time around I’m going to look at high-resolution timers and a few oddities in the way the x86_64 emulation on the M1 presents itself, that lead to some potential “gotchas”.
I’ve created a small program to demonstrate the issues I discuss here, which you can download to run yourself. It’s
(e.g.
src/stats-timing.cc which is itself used by the micro-benchmarks in the LOMP
Why Worry About Timers?
For micro-benchmarks it is useful to have high-resolution, low-overhead timers, ideally ones which we can access in a single instruction. While the most portable thing to do is to use the