The InOrder CPU model was designed to provide a generic framework to simulate in-order pipelines with an arbitrary ISA and with arbitrary pipeline descriptions. The model was originally conceived by closely mirroring the O3CPU model to provide a simulation framework that would operate at the "Tick" granularity. We then abstract the individual stages in the O3 model to provide generic pipeline stages for the InOrder CPU to leverage in creating a user-defined amount of pipeline stages. Additionally, we abstract each component that a CPU might need to access (ALU, Branch Predictor, etc.) into a "resource" that needs to be requested by each instruction according to the resource-request model we implemented. This will potentially allow for researchers to model custom pipelines without the cost of designing the complete CPU from scratch.
For more information, please check the following documentation about the InOrder model, browse the code, and also access the email@example.com (standard usage) or firstname.lastname@example.org (for developer) mailing lists:
- Pipeline Stages
- Resource-Request Modeling
- Instruction Schedules & Pipeline Descriptions
- A Day in the Life of an Instruction in the InOrderCPU model
- Other Links:
- Soumyaroop Roy has been kind enough to provide a "test-status-page" of the M5-Inorder model in the work he has been doing.
Latest versions of the InOrderCPU model can be found in the gem5-dev repository