Accurately Measuring Contention in Mesh NoCs in Time-Sensitive Embedded Systems
Jordi Cardona, Carles Hernández, Jaume Abella, Enrico Mezzetti, Francisco Javier Cazorla · ACM Transactions on Design Automation of Electronic Systems · 2023
The computing capacity demanded by embedded systems is on the rise as software implements more functionalities, ranging from best-effort entertainment functions to performance-guaranteed safety-related functions. Heterogeneous manycore processors, using wormhole mesh (wmesh) Network-on-Chips (NoCs) as the main communication means, and contention block among applications, are increasingly considered to deliver the required computing performance. Most research efforts on software timing analysis have focused on deriving bounds (estimates) to the contention that tasks can suffer when accessing wmesh NoCs. However, less effort has been devoted to an equally important problem, namely,accuratelymeasuring the actual contention tasks generate each other on the wmesh which is instrumental during system validation to diagnose any software timing misbehavior and determine which tasks are particularly affected by contention on specific wmesh routers. In this article, we work on the foundations ofcontention measuringin wmesh NoCs and propose and explain the rationale of agolden metric, called taskPairWise Contention(PWC). PWC allows ascribing the actual share of the contention a given task suffers in the wmesh to each of its co-runner tasks at packet level. We also introduce and formalize aGolden Reference Value(GRV) for PWC that specifically defines a criterion to fairly break down the contention suffered by a task among its co-runner tasks in the wmesh. Our evaluation shows that GRV effectively captures how contention occurs by identifying the actual core (task) causing contention and whether contention is caused by local or remote interference in the wmesh.