OpenACC Shines in Global Climate/Weather Codes

By John Russell

November 14, 2017

OpenACC, the directive-based parallel programming model used mostly for porting codes to GPUs for use on heterogeneous systems, came to SC17 touting impressive speedups of climate codes as well as its latest release, version 2.6, which adds deep copy functionality but otherwise minor enhancements. The progress reported demonstrates OpenACC’s steady and impactful penetration of the HPC landscape.

Three of the top five HPC applications[i] (ANSYS Fluent, Gaussian, and VASP) now support and use OpenACC, and on the order of 85 applications have been “accelerated” at hackathons since 2014. The work on climate codes – conducted over a few years – includes recent successful efforts by a 2017 Gordon Bell finalist to speed up the widely used Community Atmosphere Model (CAM) from The National Center for Atmospheric Research (NCAR) on China’s Sunway TaihuLight Supercomputer.

“OpenACC allowed us to scale the CAM-SE to over 1.8 million Sunway cores with a simulation speed of over 3 simulated years per day,” said Haohuan Fu, deputy director of the National Supercomputing Center in Wuxi NAD in OpenACC’s SC17 announcement. “Without OpenACC, the team would have spent years coding for the complexity of the components in the TaihuLight Supercomputer.”

It seems increasingly clear that OpenACC is finding its place in the HPC toolbox. The spotlighting of work done with climate and weather forecasting codes is one example.

Code speedup in climate research is important because of the time scales tackled. Stan Posey, program manager, earth system modeling solution development at NVIDIA, told HPCwire, “Climate research might model decades of climate behavior and so you want to achieve as many simulated years per day as you can. I believe at the Department of Energy they have gotten to about 1.5 simulated years per day which is about the best I have seen until this announcement.”

He noted the work on Sunway “is not related to GPUs; it’s just strictly the Chinese indigenous system but they used OpenACC because they don’t have the kinds of tools and compilers and so forth. It’s still such a new design.”

It’s worth pointing out that most climate models have two distinct parts, according to Posey, “One half to solve what’s called the dynamics and one half to solve the physics. The dynamics covers the transport or the CFD that’s required in these models. Then we have the physics which handles processes such as turbulence and so on.” The two tasks have somewhat different computational requirements.

“The [physics] have a higher opportunity for performance gains because they operate not necessarily embarrassingly parallel but they operate in individual vertical columns so you can process many of these at once, which is what GPUs really like. Meanwhile the dynamics part of the model is about 50 percent of the total profile and that’s nearly always going to be limited to the 2X-3X range improvement,” he said. The latter limits potential performance gains for the overall model. Speedups are achieved by attacking amenable portions of the code.

OpenACC has been proving its effectiveness in climate models. NCAR, for example, developed an atmospheric model called Model for Prediction Across Scales (MPAS). In collaboration with the University of Wyoming, and the Korea Institute of Science and Technology Information (KISTI), the team evaluated various platforms and programming models, and implemented the MPAS with OpenACC directives to take advantage of fine grain parallel processing on GPUs. Scientists at NCAR and University of Wyoming developed OpenACC code for the MPAS dynamical core and scientists at KISTI developed OpenACC code for the MPAS physics in a project that will implement the full MPAS model on GPUs.

“Our team has been investigating OpenACC as a pathway to higher performance, and with performance portability for the MPAS global atmospheric model,” said Rich Loft, director of technology development at the NCAR Computational Information and Systems Laboratory in the release. “Using this approach for the MPAS dynamical core, we have achieved speedups on a single P100 GPU equivalent to nearly 3 CPU nodes on our new Cheyenne supercomputer.”

Other climate and weather forecasting work cited by OpenACC included:

  • COSMO. Scientists at MeteoSwiss, ETH Zurich, and the Swiss National Supercomputing Center (CSCS) have developed the physics of the COSMO regional atmospheric model in OpenACC to deploy on GPUs for use in operational numerical weather prediction, and climate research.
  • IFS. Collaboration with ECMWF in the ESCAPE Project has demonstrated speedups of more than an order of magnitude when optimizing existing GPU code for the spectral transform operations in the IFS Details were presented at the ESCAPE Workshop during Sep 2017.
  • NICAM. Computational scientists at RIKEN have achieved GPU factors speedup over CPU-only, for the NICAM-DC (dynamical core) project using OpenACC on more than 1000 GPU nodes of the TSUBAME 2.5 supercomputer at the Tokyo Institute of Technology.
  • The paper “Parallelization and Performance of the NIM Weather Model on CPU, GPU, and MIC Processors,” published in the Oct 2017 edition of BAMS, describes the OpenACC and GPU developments by scientists at the NOAA Earth System Research Laboratory to achieve performance portability with the same FORTRAN code compiled across various types of HPC platforms.

OpenACC also presented favorable benchmarks for speeding up ANSYS Fluent, Guassian, and VASP with significant speedups.

“On the right side of the slider are the CAAR codes (Center for Accelerated Application Readiness) for CORAL systems, and five of those also use OpenACC to use the accelerator but also to express parallelism potentially for the CPU side.” CARR is a collaborative effort of application development teams and staff from the OLCF Scientific Computing group, CAAR is focused on redesigning, porting, and optimizing application codes for Summit’s hybrid CPU–GPU architecture.

There wasn’t much change in membership. Michigan State University has completed the process and Juckeland said another organization would soon complete the process. He also emphasized OpenACC’s commitment supporting many platforms. Arm is still not supported. AMD was a late addition to the SC17 briefing slide.

[i] Top five HPC applications according to Intersect360 Research: 1 Gromacs, 2 ANSYS Fluent, 3 Gaussian, 4 VASP, and 5 NAMD

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

InfiniBand Still Tops in Supercomputing

July 19, 2018

In the competitive global HPC landscape, system and processor vendors, nations and end user sites certainly get a lot of attention--deservedly so--but more than ever, the network plays a crucial role. While fast, perform Read more…

By Tiffany Trader

HPC for Life: Genomics, Brain Research, and Beyond

July 19, 2018

During the past few decades, the life sciences have witnessed one landmark discovery after another with the aid of HPC, paving the way toward a new era of personalized treatments based on an individual’s genetic makeup Read more…

By Warren Froelich

WCRP’s New Strategic Plan for Climate Research Highlights the Importance of HPC

July 19, 2018

As climate modeling increasingly leverages exascale computing and researchers warn of an impending computing gap in climate research, the World Climate Research Programme (WCRP) is developing its new Strategic Plan – and high-performance computing is slated to play a critical role. Read more…

By Oliver Peckham

HPE Extreme Performance Solutions

Introducing the First Integrated System Management Software for HPC Clusters from HPE

How do you manage your complex, growing cluster environments? Answer that big challenge with the new HPC cluster management solution: HPE Performance Cluster Manager. Read more…

IBM Accelerated Insights

Are Your Software Licenses Impeding Your Productivity?

In my previous article, Improving chip yield rates with cognitive manufacturing, I highlighted the costs associated with semiconductor manufacturing, and how cognitive methods can yield benefits in both design and manufacture.  Read more…

U.S. Exascale Computing Project Releases Software Technology Progress Report

July 19, 2018

As is often noted the race to exascale computing isn’t just about hardware. This week the U.S. Exascale Computing Project (ECP) released its latest Software Technology (ST) Capability Assessment Report detailing progress so far. Read more…

By John Russell

InfiniBand Still Tops in Supercomputing

July 19, 2018

In the competitive global HPC landscape, system and processor vendors, nations and end user sites certainly get a lot of attention--deservedly so--but more than Read more…

By Tiffany Trader

HPC for Life: Genomics, Brain Research, and Beyond

July 19, 2018

During the past few decades, the life sciences have witnessed one landmark discovery after another with the aid of HPC, paving the way toward a new era of perso Read more…

By Warren Froelich

D-Wave Breaks New Ground in Quantum Simulation

July 16, 2018

Last Friday D-Wave scientists and colleagues published work in Science which they say represents the first fulfillment of Richard Feynman’s 1982 notion that Read more…

By John Russell

AI Thought Leaders on Capitol Hill

July 14, 2018

On Thursday, July 12, the House Committee on Science, Space, and Technology heard from four academic and industry leaders – representatives from Berkeley Lab, Argonne Lab, GE Global Research and Carnegie Mellon University – on the opportunities springing from the intersection of machine learning and advanced-scale computing. Read more…

By Tiffany Trader

HPC Serves as a ‘Rosetta Stone’ for the Information Age

July 12, 2018

In an age defined and transformed by its data, several large-scale scientific instruments around the globe might be viewed as a ‘mother lode’ of precious data. With names seemingly created for a ‘techno-speak’ glossary, these interferometers, cyclotrons, sequencers, solenoids, satellite altimeters, and cryo-electron microscopes are churning out data in previously unthinkable and seemingly incomprehensible quantities -- billions, trillions and quadrillions of bits and bytes of electro-magnetic code. Read more…

By Warren Froelich

Tsinghua Powers Through ISC18 Field

July 10, 2018

Tsinghua University topped all other competitors at the ISC18 Student Cluster Competition with an overall score of 88.43 out of 100. This gives Tsinghua their s Read more…

By Dan Olds

HPE, EPFL Launch Blue Brain 5 Supercomputer

July 10, 2018

HPE and the Ecole Polytechnique Federale de Lausannne (EPFL) Blue Brain Project yesterday introduced Blue Brain 5, a new supercomputer built by HPE, which displ Read more…

By John Russell

Pumping New Life into HPC Clusters, the Case for Liquid Cooling

July 10, 2018

High Performance Computing (HPC) faces some daunting challenges in the coming years as traditional, industry-standard systems push the boundaries of data center Read more…

By Scott Tease

Leading Solution Providers

SC17 Booth Video Tours Playlist

Altair @ SC17


AMD @ SC17


ASRock Rack @ SC17

ASRock Rack



DDN Storage @ SC17

DDN Storage

Huawei @ SC17


IBM @ SC17


IBM Power Systems @ SC17

IBM Power Systems

Intel @ SC17


Lenovo @ SC17


Mellanox Technologies @ SC17

Mellanox Technologies

Microsoft @ SC17


Penguin Computing @ SC17

Penguin Computing

Pure Storage @ SC17

Pure Storage

Supericro @ SC17


Tyan @ SC17


Univa @ SC17


  • arrow
  • Click Here for More Headlines
  • arrow
Do NOT follow this link or you will be banned from the site!
Share This