# gem5/gem5

The official repository for the gem5 computer-system architecture simulator.

Repository: https://github.com/gem5/gem5
Canonical: https://ross.abutalabs.com/products/gem5
Homepage: http://www.gem5.org
Language: C++
License: BSD-3-Clause
License Family: permissive
Topics: architecture, arm, modeling, open-source, risc-v, simulation, simulator, x86
Last push: 2026-08-26T21:19:07+00:00

## Health v2 (maintenance only)
Score: 88/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 68, longevity 100
- inputs: {"age_days": 4292, "days_push": 7, "days_rel": 134, "gap_med": 67, "n_releases_24m": 8}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2771, forks 1951 (observed 2026-08-28T04:07:18.884471+00:00)

## What it is
gem5 is the official open-source computer-system architecture simulator for research and teaching, modeling processor microarchitecture and full systems across multiple ISAs (x86, ARM, RISC-V, POWER, MIPS, SPARC). It provides interchangeable CPU models, a detailed event-driven memory system, and Python-configurable simulation setups.

## Use cases
- simulate a new CPU microarchitecture design
- evaluate cache hierarchy and DRAM configurations
- run full-system Linux boot simulation for ARM or RISC-V
- model multicore systems with cache coherence protocols
- teach computer architecture with hands-on simulation
- benchmark system software changes against simulated hardware

## When to choose
- you need cycle-level or full-system computer architecture simulation
- you are doing academic or industrial hardware design research
- you need to model multiple ISAs with a modular, extensible framework

## When to avoid
- you need fast emulation for running software, not architectural modeling (use QEMU)
- you need GPU or accelerator simulation beyond gem5's model coverage
- you want a lightweight tool - gem5 builds are large and slow to compile

## Facets
- artifact type: library
- maturity: active
- function: simulation, developer-tools, benchmarking
- domain: computer-vision, hardware, operating-systems
- platform: cpp, python
- tags: computer-architecture, cpu-models, memory-system, isa-simulation, full-system-simulation, academic-research, risc-v, arm, x86, research, linux, macos

## Member repositories
- gem5/gem5 (main) score 88

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:18.884471+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T08:16:39.253599+00:00, confidence not recorded.
  - readme: https://github.com/gem5/gem5 (fetched 2026-08-28T04:07:18.884471+00:00, sha 0bb4dd2116a1)
  - homepage: http://www.gem5.org (fetched 2026-08-29T09:56:11.210839+00:00, sha 165b9922b6aa)
  - site_page: https://www.gem5.org/documentation/general_docs/kconfig_build_system (fetched 2026-08-29T09:56:11.227505+00:00, sha e34417d771dc)
  - site_page: https://www.gem5.org/about (fetched 2026-08-29T09:56:11.213103+00:00, sha 5715763e1184)
  - site_page: https://www.gem5.org/documentation (fetched 2026-08-29T09:56:11.215388+00:00, sha 625b67e7b638)
  - site_page: https://www.gem5.org/documentation/learning_gem5/introduction (fetched 2026-08-29T09:56:11.218162+00:00, sha baa41d26f10d)
  - site_page: https://www.gem5.org/documentation/gem5art/introduction (fetched 2026-08-29T09:56:11.220441+00:00, sha 777ccc3c38ca)
  - site_page: https://www.gem5.org/documentation/reporting_problems (fetched 2026-08-29T09:56:11.222246+00:00, sha 6beb9df90f6f)
  - site_page: https://www.gem5.org/documentation/general_docs/common-errors (fetched 2026-08-29T09:56:11.223861+00:00, sha fda08fef65b9)
  - site_page: https://www.gem5.org/documentation/general_docs/moving_to_github (fetched 2026-08-29T09:56:11.225778+00:00, sha e841b6d2e188)
- Data as of 2026-08-30T08:39:29.467469+00:00.