What is RAJA?ΒΆ

RAJA is a collection of C++ software abstractions, being developed at Lawrence Livermore National Laboratory (LLNL), that enable architecture portability for HPC applications. The overarching goals of RAJA are to:

  • Make existing (production) applications portable with minimal disruption
  • Provide a model for new applications so that they are portable from inception.

RAJA uses standard C++11 – C++ is the predominant programming language in which many LLNL codes are written. RAJA is rooted in a perspective based on substantial experience working on production mesh-based multiphysics applications at LLNL. Another goal of RAJA is to enable application developers to adapt RAJA concepts and specialize them for different code implementation patterns and C++ usage, since data structures and algorithms vary widely across applications.

RAJA shares goals and concepts found in other C++ portability abstraction approaches, such as Kokkos and Thrust. However, it includes concepts that are absent in other models and which are fundamental to LLNL codes.

It is important to note that RAJA is very much a work-in-progress. The community of researchers and application developers at LLNL that are actively contributing to it and developing new capabilities is growing. The publicly-released version contains only core pieces of RAJA as they exist today. While the basic interfaces are fairly stable, the implementation of the underlying concepts is being refined. Additional features will appear in future releases.

RAJA lives in a github repository. To clone the repo, use the command:

$ git clone https://github.com/llnl/raja.git

Then, you can build RAJA like any other CMake project, provided you have a C++ compiler that supports the C++11 standard. The simplest way to build the code is to do the following in the top-level RAJA directory (in-source builds are not allowed!):

$ mkdir build
$ cd build
$ cmake ../
$ make

For details about RAJA configuration and build options, please see Configuring and Building RAJA.

If you are interested in keeping up with RAJA development and communicating with developers and users, please join our mailing list over at Google Groups - RAJA Google Group.

If you have questions, find a bug, or have ideas about expanding the functionality or applicability of RAJA and are interested in contributing to its development, please do not hesitate to contact us. We are always interested in improving RAJA and exploring new ways to use it.

See also

More detailed discussion of RAJA, including its use in proxy apps included in the RAJA source distribution can be found in these reports:

The RAJA Portability Layer: Overview and Status (2014)

RAJA Overview (extracted from ASC Tri-lab Co-design Level 2 Milestone Report 2015)

Newer reports and other material will appear here over time.