Late Breaking Results: A RISC-V ISA Extension for Chaining in Scalar Processors

Fuente: arXiv
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Hauptverfasser: Colagrande, Luca, Jonnalagadda, Jayanth, Benini, Luca
Format: Preprint
Veröffentlicht: 2025
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author Colagrande, Luca
Jonnalagadda, Jayanth
Benini, Luca
author_facet Colagrande, Luca
Jonnalagadda, Jayanth
Benini, Luca
contents Modern general-purpose accelerators integrate a large number of programmable area- and energy-efficient processing elements (PEs), to deliver high performance while meeting stringent power delivery and thermal dissipation constraints. In this context, PEs are often implemented by scalar in-order cores, which are highly sensitive to pipeline stalls. Traditional software techniques, such as loop unrolling, mitigate the issue at the cost of increased register pressure, limiting flexibility. We propose scalar chaining, a novel hardware-software solution, to address this issue without incurring the drawbacks of traditional software-only techniques. We demonstrate our solution on register-limited stencil codes, achieving >93% FPU utilizations and a 4% speedup and 10% higher energy efficiency, on average, over highly-optimized baselines. Our implementation is fully open source and performance experiments are reproducible using free software.
format Preprint
id arxiv_https___arxiv_org_abs_2503_20609
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Late Breaking Results: A RISC-V ISA Extension for Chaining in Scalar Processors
Colagrande, Luca
Jonnalagadda, Jayanth
Benini, Luca
Hardware Architecture
Modern general-purpose accelerators integrate a large number of programmable area- and energy-efficient processing elements (PEs), to deliver high performance while meeting stringent power delivery and thermal dissipation constraints. In this context, PEs are often implemented by scalar in-order cores, which are highly sensitive to pipeline stalls. Traditional software techniques, such as loop unrolling, mitigate the issue at the cost of increased register pressure, limiting flexibility. We propose scalar chaining, a novel hardware-software solution, to address this issue without incurring the drawbacks of traditional software-only techniques. We demonstrate our solution on register-limited stencil codes, achieving >93% FPU utilizations and a 4% speedup and 10% higher energy efficiency, on average, over highly-optimized baselines. Our implementation is fully open source and performance experiments are reproducible using free software.
title Late Breaking Results: A RISC-V ISA Extension for Chaining in Scalar Processors
topic Hardware Architecture
url https://arxiv.org/abs/2503.20609