Enforcing Predictability of Many-cores with DCFNoC

Abstract

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] The ever need for higher performance forces industry to include technology based on multi-processors system on chip (MPSoCs) in their safety-critical embedded systems. MPSoCs include a network-on-chip (NoC) to interconnect the cores between them and with memory and the rest of shared resources. Unfortunately, the inclusion of NoCs compromises guaranteeing time predictability as network-level conflicts may occur. To overcome this problem, in this paper we propose DCFNoC, a new time-predictable NoC design paradigm where conflicts within the network are eliminated by design. This new paradigm builds on top of the Channel Dependency Graph (CDG) in order to deterministically avoid network conflicts. The network guarantees predictability to applications and is able to naturally inject messages using a TDM period equal to the optimal theoretical bound without the need of using a computationally demanding offline process. DCFNoC is integrated in a tile-based many-core system and adapted to its memory hierarchy. Our results show that DCFNoC guarantees time predictability avoiding network interference among multiple running applications. DCFNoC always guarantees performance and also improves wormhole performance in a 4 × 4 setting by a factor of 3.7× when interference traffic is injected. For a 8 × 8 network differences are even larger. In addition, DCFNoC obtains a total area saving of 10.79% over a standard wormhole implementation.This work has been supported by MINECO under Grant BES-2016-076885, by MINECO and funds from the European ERDF under Grant TIN2015-66972-C05-1-R and Grant RTI2018-098156-B-C51, and by the EC H2020 RECIPE project under Grant 801137.Picornell-Sanjuan, T.; Flich Cardo, J.; Hernández Luz, C.; Duato Marín, JF. (2021). Enforcing Predictability of Many-cores with DCFNoC. IEEE Transactions on Computers. 70(2):270-283. https://doi.org/10.1109/TC.2020.2987797S27028370