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Auteurs principaux: Fu, Zexin, Tedeschi, Riccardo, Ottavi, Gianmarco, Wistoff, Nils, Fuguet, César, Rossi, Davide, Benini, Luca
Format: Preprint
Publié: 2025
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Accès en ligne:https://arxiv.org/abs/2505.24363
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author Fu, Zexin
Tedeschi, Riccardo
Ottavi, Gianmarco
Wistoff, Nils
Fuguet, César
Rossi, Davide
Benini, Luca
author_facet Fu, Zexin
Tedeschi, Riccardo
Ottavi, Gianmarco
Wistoff, Nils
Fuguet, César
Rossi, Davide
Benini, Luca
contents Open-source RISC-V cores are increasingly demanded in domains like automotive and space, where achieving high instructions per cycle (IPC) through superscalar and out-of-order (OoO) execution is crucial. However, high-performance open-source RISC-V cores face adoption challenges: some (e.g. BOOM, Xiangshan) are developed in Chisel with limited support from industrial electronic design automation (EDA) tools. Others, like the XuanTie C910 core, use proprietary interfaces and protocols, including non-standard AXI protocol extensions, interrupts, and debug support. In this work, we present a modified version of the OoO C910 core to achieve full RISC-V standard compliance in its debug, interrupt, and memory interfaces. We also introduce CVA6S+, an enhanced version of the dual-issue, industry-supported open-source CVA6 core. CVA6S+ achieves 34.4% performance improvement over CVA6 core. We conduct a detailed performance, area, power, and energy analysis on the superscalar out-of-order C910, superscalar in-order CVA6S+ and vanilla, single-issue in-order CVA6, all implemented in a 22nm technology and integrated into Cheshire, an open-source modular SoC. We examine the performance and efficiency of different microarchitectures using the same ISA, SoC, and implementation with identical technology, tools, and methodologies. The area and performance rankings of CVA6, CVA6S+, and C910 follow expected trends: compared to the scalar CVA6, CVA6S+ shows an area increase of 6% and an IPC improvement of 34.4%, while C910 exhibits a 75% increase in area and a 119.5% improvement in IPC. However, efficiency analysis reveals that CVA6S+ leads in area efficiency (GOPS/mm2), while the C910 is highly competitive in energy efficiency (GOPS/W). This challenges the common belief that high performance in superscalar and out-of-order cores inherently comes at a significant cost in area and energy efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2505_24363
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ramping Up Open-Source RISC-V Cores: Assessing the Energy Efficiency of Superscalar, Out-of-Order Execution
Fu, Zexin
Tedeschi, Riccardo
Ottavi, Gianmarco
Wistoff, Nils
Fuguet, César
Rossi, Davide
Benini, Luca
Hardware Architecture
Open-source RISC-V cores are increasingly demanded in domains like automotive and space, where achieving high instructions per cycle (IPC) through superscalar and out-of-order (OoO) execution is crucial. However, high-performance open-source RISC-V cores face adoption challenges: some (e.g. BOOM, Xiangshan) are developed in Chisel with limited support from industrial electronic design automation (EDA) tools. Others, like the XuanTie C910 core, use proprietary interfaces and protocols, including non-standard AXI protocol extensions, interrupts, and debug support. In this work, we present a modified version of the OoO C910 core to achieve full RISC-V standard compliance in its debug, interrupt, and memory interfaces. We also introduce CVA6S+, an enhanced version of the dual-issue, industry-supported open-source CVA6 core. CVA6S+ achieves 34.4% performance improvement over CVA6 core. We conduct a detailed performance, area, power, and energy analysis on the superscalar out-of-order C910, superscalar in-order CVA6S+ and vanilla, single-issue in-order CVA6, all implemented in a 22nm technology and integrated into Cheshire, an open-source modular SoC. We examine the performance and efficiency of different microarchitectures using the same ISA, SoC, and implementation with identical technology, tools, and methodologies. The area and performance rankings of CVA6, CVA6S+, and C910 follow expected trends: compared to the scalar CVA6, CVA6S+ shows an area increase of 6% and an IPC improvement of 34.4%, while C910 exhibits a 75% increase in area and a 119.5% improvement in IPC. However, efficiency analysis reveals that CVA6S+ leads in area efficiency (GOPS/mm2), while the C910 is highly competitive in energy efficiency (GOPS/W). This challenges the common belief that high performance in superscalar and out-of-order cores inherently comes at a significant cost in area and energy efficiency.
title Ramping Up Open-Source RISC-V Cores: Assessing the Energy Efficiency of Superscalar, Out-of-Order Execution
topic Hardware Architecture
url https://arxiv.org/abs/2505.24363