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Revisiting Timing Anomalies in Predictable In-Order Pipelines

Authors Lilia Rouizi , Mihail Asavoae , Benjamin Binder , Lionel Rieg , Florian Brandner

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ACM Subject Classification
  • Computer systems organization → Architectures
  • Computer systems organization → Real-time systems
Keywords
  • Timing Anomalies
  • Causality
  • Timing Predictability
  • Timing Analysis

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Abstract

The quality of timing guarantees ensured through worst-case-execution time analysis and schedulability tests - required to be both sound and precise - is directly influenced by the predictability properties of the execution platform. A platform is considered predictable when safe and precise bounds can be computed through analysis tools. Counter-intuitive and Amplification Timing Anomalies (TAs) are detrimental to predictability and thus may make it much harder/impossible to compute such bounds. In order to address this issue, research has followed two orthogonal approaches, (i) designing predictable execution platforms and (ii) characterizing counter-intuitive TAs through formal definitions. However, predictable designs rarely apply any formal definitions of timing anomalies.
This paper aims at investigating precisely this relationship. We first show how a previously proposed definition of counter-intuitive TAs can be applied to the predictable in-order processor SIC. We then extend this approach in order to provide the first formal definition of both counter-intuitive and amplification effects. The proposed definitions are then evaluated on a regular in-order processor as well as the predictable SIC core using a systematic approach that allows to assess their applicability and relevance. Finally, we prove, for the first time, the absence of some, but not all, TA effects in SIC.

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Lilia Rouizi, Mihail Asavoae, Benjamin Binder, Lionel Rieg, and Florian Brandner. Revisiting Timing Anomalies in Predictable In-Order Pipelines. In 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 335, pp. 19:1-19:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025) https://doi.org/10.4230/LIPIcs.ECRTS.2025.19

Author Details

Lilia Rouizi
  • Université Paris-Saclay, CEA List, Palaiseau, France
Mihail Asavoae
  • Université Paris-Saclay, CEA List, Palaiseau, France
Benjamin Binder
  • Independent researcher, Paris, France
Lionel Rieg
  • Grenoble INP - UGA, Université Grenoble Alpes, Verimag, Grenoble, France
Florian Brandner
  • LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France

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