Interesting read.<p>It's quite intriguing that x86-64 processors <i>of different microarchitectures and from different vendors</i> basically all have similar non-determinsm for retired instruction counters but — at least in the authors’ brief review — IA64 (Itanium), POWER, and SPARC appear to be too deterministic.<p>I can't really see any good explanation for why this would be hard to get right specifically on x86-64. Can anyone else?<p>(And are there any more recent or thorough results on other archs, particularly arm64?)