ACALSim: A Scalable Parallel Simulation Framework for High-Performance System Design Space Exploration

Fuente: arXiv
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Auteurs principaux: Lin, Wei-Fen, Chang, Jen-Chien, Chen, Yen-Po, Tai, Zi-Yi, Chang, Yu-Cheng, Chiang, Chia-Pao, Lee, Yu-Yang, Wan, Yu-Jie
Format: Preprint
Publié: 2026
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author Lin, Wei-Fen
Chang, Jen-Chien
Chen, Yen-Po
Tai, Zi-Yi
Chang, Yu-Cheng
Chiang, Chia-Pao
Lee, Yu-Yang
Wan, Yu-Jie
author_facet Lin, Wei-Fen
Chang, Jen-Chien
Chen, Yen-Po
Tai, Zi-Yi
Chang, Yu-Cheng
Chiang, Chia-Pao
Lee, Yu-Yang
Wan, Yu-Jie
contents Architectural simulation has become the critical bottleneck limiting design space exploration for high-performance computing systems. Modern GPUs and AI accelerators -- with hundreds to thousands of tightly-coupled components -- demand simulation frameworks that deliver efficient parallelism and scalable single-node execution. Existing frameworks fall short: SST focuses on multi-node MPI scalability but struggles with intra-node scaling, while GPGPU-Sim remains largely single-threaded. Critically, none expose a mechanism for users to optimize threading for their specific workloads. We introduce ACALSim, a scalable parallel simulation framework providing infrastructure and APIs for building high-performance simulators -- timing-model accuracy remains the responsibility of simulator developers. Its key innovation is a pluggable thread-management architecture that lets developers implement custom scheduling strategies tailored to specific simulation patterns, absent in existing frameworks. Complementing it are (1) event-driven execution with fast-forward to eliminate idle-cycle overhead, (2) a shared-memory data model enabling zero-copy communication, and (3) a two-phase parallel execution model for deterministic thread scaling. We demonstrate ACALSim through HPCSim, a GPU simulator targeting A100-class architectures. Against an SST implementation using identical shared timing cores to isolate framework overhead, ACALSim achieves over 14x speedup with 41% lower memory footprint; hardware validation confirms 0.72--1.22x cycle-count correlation with A100 measurements. While SST fails to complete 256+ thread-block workloads within practical time limits, ACALSim simulates full LLaMA transformer layers (single block) in 17.7 minutes for LLaMA-7B and 30.4 minutes for LLaMA-13B -- enabling design space exploration that SST cannot achieve.
format Preprint
id arxiv_https___arxiv_org_abs_2605_22936
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ACALSim: A Scalable Parallel Simulation Framework for High-Performance System Design Space Exploration
Lin, Wei-Fen
Chang, Jen-Chien
Chen, Yen-Po
Tai, Zi-Yi
Chang, Yu-Cheng
Chiang, Chia-Pao
Lee, Yu-Yang
Wan, Yu-Jie
Hardware Architecture
Performance
Architectural simulation has become the critical bottleneck limiting design space exploration for high-performance computing systems. Modern GPUs and AI accelerators -- with hundreds to thousands of tightly-coupled components -- demand simulation frameworks that deliver efficient parallelism and scalable single-node execution. Existing frameworks fall short: SST focuses on multi-node MPI scalability but struggles with intra-node scaling, while GPGPU-Sim remains largely single-threaded. Critically, none expose a mechanism for users to optimize threading for their specific workloads. We introduce ACALSim, a scalable parallel simulation framework providing infrastructure and APIs for building high-performance simulators -- timing-model accuracy remains the responsibility of simulator developers. Its key innovation is a pluggable thread-management architecture that lets developers implement custom scheduling strategies tailored to specific simulation patterns, absent in existing frameworks. Complementing it are (1) event-driven execution with fast-forward to eliminate idle-cycle overhead, (2) a shared-memory data model enabling zero-copy communication, and (3) a two-phase parallel execution model for deterministic thread scaling. We demonstrate ACALSim through HPCSim, a GPU simulator targeting A100-class architectures. Against an SST implementation using identical shared timing cores to isolate framework overhead, ACALSim achieves over 14x speedup with 41% lower memory footprint; hardware validation confirms 0.72--1.22x cycle-count correlation with A100 measurements. While SST fails to complete 256+ thread-block workloads within practical time limits, ACALSim simulates full LLaMA transformer layers (single block) in 17.7 minutes for LLaMA-7B and 30.4 minutes for LLaMA-13B -- enabling design space exploration that SST cannot achieve.
title ACALSim: A Scalable Parallel Simulation Framework for High-Performance System Design Space Exploration
topic Hardware Architecture
Performance
url https://arxiv.org/abs/2605.22936