ffd0680a2c
This is a followed up fix to #791 mem-ruby: Fix possible dirty line loss in CHI when ReadShared hit on UD line. UD_RU line may have stale data since the upstream could have updated the line, so its local cache line data is treated as invalid (dataValid=false). But when the line is evicted, it must be written back to downstream because the upstream may have the line in clean state (UC). This change fixes it by performing copy back the UD_RU line while keeping its dataValid as false. Example error case: - L3 was in UD_RSC and being evicted without back-invalidation. LLC (HN) was in RU state. - Because there's still upstream sharer, L3 sends WriteClean. - Because the data state was unique and dirty, L3 sends CBWrData_UD_PD. - LLC becomes UD_RU. - When the line is evicted from LLC (LocalHN_Eviction), the line is just dropped, causing the loss of the dirty copy Co-authored-by: Minje Jun <minje.jun@samsung.com>
The gem5 Simulator
This is the repository for the gem5 simulator. It contains the full source code for the simulator and all tests and regressions.
The gem5 simulator is a modular platform for computer-system architecture research, encompassing system-level architecture as well as processor microarchitecture. It is primarily used to evaluate new hardware designs, system software changes, and compile-time and run-time system optimizations.
The main website can be found at http://www.gem5.org.
Testing status
Note: These regard tests run on the develop branch of gem5: https://github.com/gem5/gem5/tree/develop.
Getting started
A good starting point is http://www.gem5.org/about, and for more information about building the simulator and getting started please see http://www.gem5.org/documentation and http://www.gem5.org/documentation/learning_gem5/introduction.
Building gem5
To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/documentation/general_docs/building for more details concerning the minimum versions of these tools.
Once you have all dependencies resolved, execute
scons build/ALL/gem5.opt to build an optimized version of the gem5 binary
(gem5.opt) containing all gem5 ISAs. If you only wish to compile gem5 to
include a single ISA, you can replace ALL with the name of the ISA. Valid
options include ARM, NULL, MIPS, POWER, RISCV, SPARC, and X86
The complete list of options can be found in the build_opts directory.
See https://www.gem5.org/documentation/general_docs/building for more information on building gem5.
The Source Tree
The main source tree includes these subdirectories:
- build_opts: pre-made default configurations for gem5
- build_tools: tools used internally by gem5's build process.
- configs: example simulation configuration scripts
- ext: less-common external packages needed to build gem5
- include: include files for use in other programs
- site_scons: modular components of the build system
- src: source code of the gem5 simulator. The C++ source, Python wrappers, and Python standard library are found in this directory.
- system: source for some optional system software for simulated systems
- tests: regression tests
- util: useful utility programs and files
gem5 Resources
To run full-system simulations, you may need compiled system firmware, kernel binaries and one or more disk images, depending on gem5's configuration and what type of workload you're trying to run. Many of these resources can be obtained from https://resources.gem5.org.
More information on gem5 Resources can be found at https://www.gem5.org/documentation/general_docs/gem5_resources/.
Getting Help, Reporting bugs, and Requesting Features
We provide a variety of channels for users and developers to get help, report bugs, requests features, or engage in community discussions. Below are a few of the most common we recommend using.
- GitHub Discussions: A GitHub Discussions page. This can be used to start discussions or ask questions. Available at https://github.com/orgs/gem5/discussions.
- GitHub Issues: A GitHub Issues page for reporting bugs or requesting features. Available at https://github.com/gem5/gem5/issues.
- Jira Issue Tracker: A Jira Issue Tracker for reporting bugs or requesting features. Available at https://gem5.atlassian.net/.
- Slack: A Slack server with a variety of channels for the gem5 community to engage in a variety of discussions. Please visit https://www.gem5.org/join-slack to join.
- gem5-users@gem5.org: A mailing list for users of gem5 to ask questions or start discussions. To join the mailing list please visit https://www.gem5.org/mailing_lists.
- gem5-dev@gem5.org: A mailing list for developers of gem5 to ask questions or start discussions. To join the mailing list please visit https://www.gem5.org/mailing_lists.
Contributing to gem5
We hope you enjoy using gem5. When appropriate we advise charing your contributions to the project. https://www.gem5.org/contributing can help you get started. Additional information can be found in the CONTRIBUTING.md file.