Rensselaer's Optimistic Simulation System
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Adding the requirement of no warnings when compiling with -Wall and -Wextra
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Welcome to Simplified ROSS!

Welcome to a leaner, meaner, faster version of ROSS. While the entire history of ROSS has been preserved in this repository, a major change in the directory structure has made getting the full history of a file somewhat of a pain. You may find the now-deprecated version at the ROSS-Legacy tag in this repository. Using this repository you can compare files from the new ROSS/core to ROSS/ross. For a detailed list of changes between old ROSS and SR please visit the wiki.

Build Status Doxygen


ROSS's history starts with a one-week re-implementation of Georgia Tech Time Warp (GTW) by Shawn Pearce and Dave Bauer in 1999. After 10 years of in-house development, version 5.0 of Rensselaer's Optimistic Simulation System went live at Thus the official version history began!

Through the years ROSS has migrated from CVS, to SVN, to Git and The code was maintained by Chris Carothers and his graduate students at RPI (publications). Over the years, several features (including a shared-memory version) were implemented within ROSS. Some of these features have since been optimized out, leaving behind cruft.

In early 2015 a sleeker version of ROSS was released. Developed as Simplified ROSS (gonsie/SR), this version removed many files, functions, and variables that had become deprecated over time.


  1. ROSS is written in C standard and thus requires a C compiler (C11 is prefered, but not required).
  2. The build system is CMake, and we require version 2.8 or higher.
  3. ROSS relies on MPI. We recommend the MPICH implementation.

Startup Instructions

  1. Clone the repository to your local machine:
git clone -b master --single-branch

Since the ROSS repostiory is quite large, it is recommended that you only clone the master branch. To speed up the clone command even more, use the --depth=1 argument.

  1. Optional Install the submodules:
git submodule init
git submodule update

Currently, ROSS includes three submodules:

  • ROSS-Models is a set of existing models
  • template-model is a starting place for new models
  • RIO is a work-in-progress checkpointing framework
  1. Optional Symlink your model to ROSS. Please this wiki page for details about creating and integrating a model with ROSS.
ln -s ~/path-to/your-existing-model models/your-model-name
  1. Create a build directory. ROSS developers typically do out-of-tree builds. See the Installation page for more details.
cd ~/directory-of-builds/
mkdir ROSS-build
cd ROSS-build
export ARCH=x86_64
export CC=mpicc
ccmake ~/path-to/ROSS
  1. Make your model(s) with one of the following commands
make -k         // ignore errors from other models
make -j 12      // parallel build
make model-name // build only one model
  1. Run your model. See this wiki page for details about the ROSS command line options.
cd ~/directory-of-builds/ROSS-build/models/your-model
./your-model --synch=1               // sequential mode
mpirun -np 2 ./your-model --synch=2  // conservative mode
mpirun -np 2 ./your-model --synch=3  // optimistic mode
./your-model --synch=4               // optimistic debug mode (note: not a parallel execution!)