CounterPoint: Using Hardware Event Counters to Refute & Refine Microarchitectural Assumptions

Abstract

Hardware event counters can reveal detailed microarchitectural behavior, but vague specifications, opaque designs, and multiplexing noise make them hard to interpret. CounterPoint tests user-specified microarchitectural models, expressed as micro-path decision diagrams, for consistency with counter data. When observations disagree, it identifies plausible missing features and uses multidimensional confidence regions to handle multiplexing noise. Applied to the Haswell memory-management unit, CounterPoint uncovers multiple undocumented or underdocumented behaviors, including a load-store-queue-side TLB prefetcher, merging page-table walkers, and abortable page-table walks.

BibTeX

@inproceedings{counterpoint,
  author = {Lindsay, Nick and Trippel, Caroline and Khandelwal, Anurag and Bhattacharjee, Abhishek},
  title = {{CounterPoint: Using Hardware Event Counters to Refute \& Refine Microarchitectural Assumptions}},
  year = {2026},
  month = mar,
  booktitle = {ACM ASPLOS},
  award = {Best Paper Award}
}