Flexus is a family of component-based C++ computer architecture simulators that build on Virtutech Simics' Micro-Architecture Interface (MAI) to enable full-system timing-accurate simulation of uni- and multiprocessor systems running unmodified commercial applications and operating systems.

Flexus encompasses both a simulation infrastructure and default simulation models. A simulator is composed of individual modules that are hooked together during compilation. A module is often the equivalent of a single hardware structure - for example, a branch predictor or a cache. A key strength of Flexus is its isolation of components: one implementation of a particular module can be swapped for a different implementation without requiring changes to any other modules.

This flexibility also allows a particular simulator to be tailored to the needs of a specific research hypothesis. If memory system performance is being evaluated, a simple bandwidth-based processor pipeline might be sufficient. Conversely, a study that closely examines microarchitecture could use a simple memory model. The Flexus core provides services, such as scheduling and statistics, that are common and useful to all simulators.

Virtutech Simics enables full-system simulation. Simics is a functional simulator that allows unmodified commercial operating systems and applications to boot and run. Flexus can hook into Simics and see the instruction stream that a real system would execute. Flexus can also control Simics' timing, so as to model out-of-order effects and speculative techniques.

Key Features

  • Built on Simics targeting the SPARC ISA
    • Timing-accurate processor, memory, and interconnect simulation
    • Component-based design leveraging C++ features and libraries
    • Easy composition of in-order and out-of-order uniprocessor and multiprocessor models
  • Built-in statistics management and simulation state checkpointing
    • Leverages SMARTS and live-points acceleration techniques
  • Current models include a uniprocessor, and a CMP and DSM derived from Piranha

Download Flexus 4.1.0