R is a free software environment for statistical computing and graphics that provides a programming language and built-in libraries of mathematics operations for statistics, data analysis, machine learning and much more. Many domain experts and researchers use the R platform and contribute R software, resulting in a large ecosystem of free software packages available through CRAN (the Comprehensive R Archive Network).

However, R, like many other high-level languages, is not performance competitive out of the box with lower-level languages like C++, especially for highly data- and computation-intensive applications. R programs tend to process large amounts of data, and often have significant independent data and task parallelism. Therefore, R applications stand to benefit from GPU acceleration. This way, R users can benefit from R’s high-level, user-friendly interface while achieving high performance.

In this article, I will introduce the computation model of R with GPU acceleration, focusing on three topics:

- accelerating R computations using CUDA libraries;
- calling your own parallel algorithms written in CUDA C/C++ or CUDA Fortran from R; and
- profiling GPU-accelerated R applications using the CUDA Profiler.

## The GPU-Accelerated R Software Stack

Figure 1 shows that there are two ways to apply the computational power of GPUs in R:

- use R GPU packages from CRAN; or
- access the GPU through CUDA libraries and/or CUDA-accelerated programming languages, including C, C++ and Fortran.

The first approach is to use existing GPU-accelerated R packages listed under High-Performance and Parallel Computing with R on the CRAN site. Examples include gputools and cudaBayesreg. These packages are very easy to install and use. On the other hand, the number of GPU packages is currently limited, quality varies, and only a few domains are covered. This will improve with time.

The second approach is to use the GPU through CUDA directly. Continue reading