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The Computer Languages & Systems Software (CLaSS) Group advances the frontiers of high-performance computing by researching, designing, and building innovative software tools, libraries, and programming models. Our work focuses on parallel programming models, compiler and runtime development, and high-performance communication libraries—delivering the performance, scalability, and portability required by today’s most demanding scientific and engineering applications.

With deep expertise in performance optimization and the development of foundational technologies like GASNet, UPC, and UPC++, CLaSS empowers scientists, engineers, and developers to fully leverage modern supercomputers. We have a proven track record of leadership in the HPC community and are committed to open collaboration with partners across academia, industry, and government.

 The CLaSS software ecosystem is built atop GASNet-EX, our high-performance communication portability layer. GASNet-EX supports a number of parallel programming models and frameworks developed by LBNL and other institutional partners. The CLaSS group additionally encompasses development of the UPC++ and Berkeley UPC programming model productivity layers, as well as the Caffeine Fortran parallel runtime.

Programming Models, Compilers, and Runtimes

We research, design, and implement advanced parallel programming models such as UPC and UPC++, along with the compilers and runtime systems that enable efficient and scalable execution on modern HPC systems. A key focus is on performance optimization, ensuring that applications and tools fully exploit the computational capabilities of leading-edge supercomputers.

 Close-up view of the back of a supercomputer or server rack, showing rows of hardware components connected by numerous blue and red network cables.

High-Performance Communication Libraries

We lead the development of network-independent communication middleware like GASNet, delivering low-latency, high-throughput communication essential for parallel applications. This expertise includes optimizing these libraries for maximum performance and portability across diverse HPC architectures.

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Cross-Disciplinary Applications

We apply our technologies to solve large-scale scientific and engineering problems, demonstrating impact in fields such as genomics, epidemiology, and numerical linear algebra by enabling unprecedented scalability and efficiency in computational research.

 Fortran Language Standard written in bold blue on a beige background

Community and Standards Leadership

We actively contribute to language standardization, open-source software, and collaborative research, fostering innovation and interoperability within the global HPC community.

GASNet

The word "GASNet" appears in large, bold, gray letters centered on a dark background with a glowing, hazy white and pink light effect behind the text.

UPC++

The image shows the text "upc" in a stylized red font, with the letter "c" shaped like a crescent moon and accompanied by two star symbols, all on a black background.

Berkeley UPC

Stylized logo with the words "Berkeley UPC Unified Parallel C" in large, light-colored text on a black background, surrounded by circuit-like lines and circles suggesting technology and connectivity.

Fortran at Berkeley Lab

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Caffeine

Diagram of a coffee cup showing a software stack. From top to bottom inside the cup: "Application," then "Caffeine," then "GASNet-EX." The cup sits on a saucer labeled "System Runtime & Memory Technologies." The cup handle is labeled vertically with the word "Compiler."

Fiats: Functional Inference and Training for Surrogates

ASCII art spelling "Fiats" in large letters, with the subtitle "Fiats: Functional Inference and Training for Surrogates" written below.

Julienne

"An illustration representing Julienne, an open-source unit testing framework for Fortran. The image features elements like code snippets, test results, and symbols for parallel computing, conveying the concept of testing and debugging in scientific software. The design is modern and clean, emphasizing the streamlined process of error identification."

Assert

An illustration depicting Assert, an open-source tool for Fortran. The image includes code logic diagrams, diagnostic outputs, and symbols of correctness and debugging, representing the tool's function in specifying and enforcing logical pre-conditions and post-conditions in scientific code. The design is technical and precise, highlighting the tool's role in debugging and ensuring code correctness.

Pagoda Paves the Way for Fast, Scalable Applications on Modern Supercomputers

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Damian Rouson Named 2024 Developer of the Year by Berkeley Lab

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Berkeley Lab’s Networking Middleware GASNet Turns 20

The text "GASNet-EX" in bold, dark letters is centered on a black background with a bright, glowing light effect behind the text.