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Non-Determinism and Overcount on Modern Hardware Performance Counters [pdf]

41 pointsby luu9 months ago

2 comments

7e9 months ago
The limitations of x86 perf. counters for deterministic replay have been known far earlier than 2021; in industry around 2005 or so. It would be nice if there were more efficient hardware support for determinism, especially multi-core.
dlenski9 months ago
Interesting read.<p>It&#x27;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&#x27;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?)