OpenACC Broadens Appeal with GCC Compiler Support

By Nicole Hemsoth

November 14, 2013

As the non-profit standards group behind the push for wider adoption via easier use of accelerators, OpenACC has quite a big job ahead. Although analysts agree that accelerators sit along a comfortable adoption curve, usability, programmability and portability are key concerns, among others.

Over the last couple of years, OpenACC has worked with user groups across academia and industry to understand what is still needed for healthier adoption of accelerators via workshops and meetings, which has produced a number of the core improvements that are available within the 2.0 spec (procedure calls, nested parallelism, more dynamic data management support and more). On top of that, the ecosystem is also rounded out by CAPS, PGI and Cray, in particular, as well as being supported by x86 and ARM vendors (and of course the accelerators from all the major players).

Of course, one of the main questions was whether the OpenACC group would be able to offer a free implementation and whether they would open source OpenACC (not the same thing, as we know). Today the group spoke to those requests by announcing that one of its new members (in addition to Louisiana State University and NOAA as of this week), Mentor Graphics, has developed OpenACC extensions that will be supported in mainstream GCC compilers.

Mentor Graphics’ Nathan Sidwell told us that this came about following their acquisition of Code Sourcery, which has a long history of producing GCC-based toolchains for Linux and embedded systems. Mentor is working on implementing OpenACC 2.0 in the GCC toolchain, which will be rolled out over the next year, making an open source implementation of OpenACC available to all users who have Linux systems. Sidwell said that they are leveraging some of the existing infrastructure in GCC for accelerated computing, but how different implementations will converge is undecided at this point as it will be up to distributors of Linux systems how they configure GCC for their offerings.

As OpenACC President, Duncan Poole, said of this development, it breaks OpenACC out of a niche where users had to make a distinct decision to go their route.  “The addition of an open source platform is critical for the broader range of heterogeneous programming that will be necessary for the next stage of growth and innovation in HPC and as a foundation to drive software development for exascale systems.”

The non-profit wants to move accelerator use for clusters beyond computer science realms and open it to a wider set of users whose background might have little to do with programming for GPUs or other accelerators. To address those users, Poole says there needs to be support for legacy applications (those that are written in Fortran, for example, or by someone who is no longer with an organization or even those that were collaboratively developed). Users with these applications usually need a way of supporting new features but don’t require custom code paths for special features, says Poole, and this is where the benefit of OpenACC can be keenly felt.

OpenACC has been in 1.0 for a couple of years with the 2.0 spec released over the summer. Since then, as mentioned, there are three commercial implementations, all of which are starting to roll out their own 2.0 implementations (Cray with their 8.2 release recently, CAPS with their announcement of full OpenACC in December and PGI in the near term with their 2014 release in January). In addition to offering key features, the most important of which are procedure calls, Michael Wolfe of PGI (recently acquired by NVIDIA) and secretary of OpenACC says they’re using feedback to address a few other issues.

Screen shot 2013-11-14 at 9.48.51 AM

The main goal is to preserve the readability of these programs and ensure cross-platform compatibility. For OpenACC to provide this, the focus is on directives—a familiar programming model that can handle a number of elements that don’t require the end user to have a deep understanding of CUDA or OpenCL. They can then do things like allocate data on the accelerator, transfer data that’s been on the host to the booster, perform a series of operations on the accelerator and then return results back to program with far more transparency than was possible before.

“All the OpenACC vendors have experienced increasing experimentation and adoption of OpenACC on a variety of applications, including weather, computational chemistry, fluid flow simulation, combustion, and many more,” said Wolfe.  “We have been getting very useful feedback from the users to drive improvements to the specification and implementations that will deliver better performance as well as overall enhanced user experience.”

As Wolfe told us, “One of the most important features for C and C++ code would be arrays in C++ classes or C structs or Fortran derived types—these are structured data types that have array members, but right now the spec has no standard way to support that and the implementations are weak in that area—so we’re working hard to make that work, in particular for C++. We undertand that C++ is a large language and has some unique features so we’re working hard with feedback to make sure we support that in a natural and satisfying manner for those many users.”

Wolfe said that without a doubt, the top feedback from their workshops and analysis is not really a surprise—“for C++ you really have to support classes and templated classes and class members that are arrays because that’s how those programs are written. That also appears in Fortran, but not as pervasive as in C++.”

In agreement with these workshops findings is one of the core contributors to OpenACC efforts, Oak Ridge National Lab. With Titan in full production and a whole new set of users porting their codes, the lab has been keen to ensure that OpenACC is stable enough to support the next class of applications being onboarded—not to mention serving as a testbed for what might be viable for exascale-class systems.

As Dr. Oscar Hernandez, Research Staff Scientist at ORNL (and OpenACC Director of Developer Adoption) told us, OpenACC is very important because it allows ORNL to program heterogeneous systems with a single programming model that lets his teams address multiple architectures with different types of memory. “It’s important for us also because it’s a way to maintain portability in our codes and at the same time take advantage of leadership-class systems at ORNL that rely on accelerators. OpenACC offers a solution that works today and is friendly to the programmer–Open source efforts also help us drive and understand more the application needs and to do research and improve and understand what we need to do to build an ecosystem aroud OpenACC in addition we like the fact that it works now and can move fast and meet more app needs as of today.”

The group will have its first booth ever at SC13, which will be manned by various members of the organization. Some schedule highlights below for those interested in this track. We shall see you there…

OpenACCatSC

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!

New GE Simulations on Summit to Advance Offshore Wind Power

August 6, 2020

The wind energy sector is a frequent user of high-power simulations, with researchers aiming to optimize wind flows and energy production from the massive turbines. Now, researchers at GE are preparing to undertake a lar Read more…

By Oliver Peckham

Research: A Survey of Numerical Methods Utilizing Mixed Precision Arithmetic

August 5, 2020

Within the past years, hardware vendors have started designing low precision special function units in response to the demand of the machine learning community and their demand for high compute power in low precision for Read more…

By Hartwig Anzt and Jack Dongarra

Implement Photonic Tensor Cores for Machine Learning?

August 5, 2020

Researchers from George Washington University have reported an approach for building photonic tensor cores that leverages phase change photonic memory to implement a neural network (NN). Their novel architecture, reporte Read more…

By John Russell

HPE Keeps Cray Brand Promise, Reveals HPE Cray Supercomputing Line

August 4, 2020

The HPC community, ever-affectionate toward Cray and its eponymous founder, can breathe a (virtual) sigh of relief. The Cray brand will live on, encompassing the pinnacle of HPE's HPC portfolio. After announcing its i Read more…

By Tiffany Trader

Machines, Connections, Data, and Especially People: OAC Acting Director Amy Friedlander Charts Office’s Blueprint for Innovation

August 3, 2020

The path to innovation in cyberinfrastructure (CI) will require continued focus on building HPC systems and secure connections between them, in addition to the increasingly important goals of data best practices and work Read more…

By Ken Chiacchia, Pittsburgh Supercomputing Center/XSEDE

AWS Solution Channel

AWS announces the release of AWS ParallelCluster 2.8.0

AWS ParallelCluster is a fully supported and maintained open source cluster management tool that makes it easy for scientists, researchers, and IT administrators to deploy and manage High Performance Computing (HPC) clusters in the AWS cloud. Read more…

Intel® HPC + AI Pavilion

Supercomputing the Pandemic: Scientific Community Tackles COVID-19 from Multiple Perspectives

Since their inception, supercomputers have taken on the biggest, most complex, and most data-intensive computing challenges—from confirming Einstein’s theories about gravitational waves to predicting the impacts of climate change. Read more…

Nvidia Said to Be Close on Arm Deal

August 3, 2020

GPU leader Nvidia Corp. is in talks to buy U.K. chip designer Arm from parent company Softbank, according to several reports over the weekend. If consummated, analysts said the acquisition would cement Nvidia’s stat Read more…

By George Leopold

HPE Keeps Cray Brand Promise, Reveals HPE Cray Supercomputing Line

August 4, 2020

The HPC community, ever-affectionate toward Cray and its eponymous founder, can breathe a (virtual) sigh of relief. The Cray brand will live on, encompassing th Read more…

By Tiffany Trader

Machines, Connections, Data, and Especially People: OAC Acting Director Amy Friedlander Charts Office’s Blueprint for Innovation

August 3, 2020

The path to innovation in cyberinfrastructure (CI) will require continued focus on building HPC systems and secure connections between them, in addition to the Read more…

By Ken Chiacchia, Pittsburgh Supercomputing Center/XSEDE

Nvidia Said to Be Close on Arm Deal

August 3, 2020

GPU leader Nvidia Corp. is in talks to buy U.K. chip designer Arm from parent company Softbank, according to several reports over the weekend. If consummated Read more…

By George Leopold

Intel’s 7nm Slip Raises Questions About Ponte Vecchio GPU, Aurora Supercomputer

July 30, 2020

During its second-quarter earnings call, Intel announced a one-year delay of its 7nm process technology, which it says it will create an approximate six-month shift for its CPU product timing relative to prior expectations. The primary issue is a defect mode in the 7nm process that resulted in yield degradation... Read more…

By Tiffany Trader

PEARC20 Plenary Introduces Five Upcoming NSF-Funded HPC Systems

July 30, 2020

Five new HPC systems—three National Science Foundation-funded “Capacity” systems and two “Innovative Prototype/Testbed” systems—will be coming onlin Read more…

By Ken Chiacchia, Pittsburgh Supercomputing Center/XSEDE

Nvidia Dominates Latest MLPerf Training Benchmark Results

July 29, 2020

MLPerf.org released its third round of training benchmark (v0.7) results today and Nvidia again dominated, claiming 16 new records. Meanwhile, Google provided e Read more…

By John Russell

$39 Billion Worldwide HPC Market Faces 3.7% COVID-related Drop in 2020

July 29, 2020

Global HPC market revenue reached $39 billion in 2019, growing a healthy 8.2 percent over 2018, according to the latest analysis from Intersect360 Research. A 3 Read more…

By Tiffany Trader

Agenting Change: PEARC20 Keynote Encourages Cultural Change to Make Tech Better, More Diverse

July 29, 2020

The tech world will need to become more diverse if it is to thrive and survive, said Cherri Pancake, director of the Northwest Alliance for Computational Resear Read more…

By Ken Chiacchia, Pittsburgh Supercomputing Center/XSEDE

Supercomputer Modeling Tests How COVID-19 Spreads in Grocery Stores

April 8, 2020

In the COVID-19 era, many people are treating simple activities like getting gas or groceries with caution as they try to heed social distancing mandates and protect their own health. Still, significant uncertainty surrounds the relative risk of different activities, and conflicting information is prevalent. A team of Finnish researchers set out to address some of these uncertainties by... Read more…

By Oliver Peckham

Supercomputer-Powered Research Uncovers Signs of ‘Bradykinin Storm’ That May Explain COVID-19 Symptoms

July 28, 2020

Doctors and medical researchers have struggled to pinpoint – let alone explain – the deluge of symptoms induced by COVID-19 infections in patients, and what Read more…

By Oliver Peckham

Intel’s 7nm Slip Raises Questions About Ponte Vecchio GPU, Aurora Supercomputer

July 30, 2020

During its second-quarter earnings call, Intel announced a one-year delay of its 7nm process technology, which it says it will create an approximate six-month shift for its CPU product timing relative to prior expectations. The primary issue is a defect mode in the 7nm process that resulted in yield degradation... Read more…

By Tiffany Trader

Supercomputer Simulations Reveal the Fate of the Neanderthals

May 25, 2020

For hundreds of thousands of years, neanderthals roamed the planet, eventually (almost 50,000 years ago) giving way to homo sapiens, which quickly became the do Read more…

By Oliver Peckham

10nm, 7nm, 5nm…. Should the Chip Nanometer Metric Be Replaced?

June 1, 2020

The biggest cool factor in server chips is the nanometer. AMD beating Intel to a CPU built on a 7nm process node* – with 5nm and 3nm on the way – has been i Read more…

By Doug Black

Nvidia Said to Be Close on Arm Deal

August 3, 2020

GPU leader Nvidia Corp. is in talks to buy U.K. chip designer Arm from parent company Softbank, according to several reports over the weekend. If consummated Read more…

By George Leopold

Neocortex Will Be First-of-Its-Kind 800,000-Core AI Supercomputer

June 9, 2020

Pittsburgh Supercomputing Center (PSC - a joint research organization of Carnegie Mellon University and the University of Pittsburgh) has won a $5 million award Read more…

By Tiffany Trader

Nvidia’s Ampere A100 GPU: Up to 2.5X the HPC, 20X the AI

May 14, 2020

Nvidia's first Ampere-based graphics card, the A100 GPU, packs a whopping 54 billion transistors on 826mm2 of silicon, making it the world's largest seven-nanom Read more…

By Tiffany Trader

Leading Solution Providers

Contributors

Australian Researchers Break All-Time Internet Speed Record

May 26, 2020

If you’ve been stuck at home for the last few months, you’ve probably become more attuned to the quality (or lack thereof) of your internet connection. Even Read more…

By Oliver Peckham

15 Slides on Programming Aurora and Exascale Systems

May 7, 2020

Sometime in 2021, Aurora, the first planned U.S. exascale system, is scheduled to be fired up at Argonne National Laboratory. Cray (now HPE) and Intel are the k Read more…

By John Russell

‘Billion Molecules Against COVID-19’ Challenge to Launch with Massive Supercomputing Support

April 22, 2020

Around the world, supercomputing centers have spun up and opened their doors for COVID-19 research in what may be the most unified supercomputing effort in hist Read more…

By Oliver Peckham

Joliot-Curie Supercomputer Used to Build First Full, High-Fidelity Aircraft Engine Simulation

July 14, 2020

When industrial designers plan the design of a new element of a vehicle’s propulsion or exterior, they typically use fluid dynamics to optimize airflow and in Read more…

By Oliver Peckham

$100B Plan Submitted for Massive Remake and Expansion of NSF

May 27, 2020

Legislation to reshape, expand - and rename - the National Science Foundation has been submitted in both the U.S. House and Senate. The proposal, which seems to Read more…

By John Russell

John Martinis Reportedly Leaves Google Quantum Effort

April 21, 2020

John Martinis, who led Google’s quantum computing effort since establishing its quantum hardware group in 2014, has left Google after being moved into an advi Read more…

By John Russell

Google Cloud Debuts 16-GPU Ampere A100 Instances

July 7, 2020

On the heels of the Nvidia’s Ampere A100 GPU launch in May, Google Cloud is announcing alpha availability of the A100 “Accelerator Optimized” VM A2 instance family on Google Compute Engine. The instances are powered by the HGX A100 16-GPU platform, which combines two HGX A100 8-GPU baseboards using... Read more…

By Tiffany Trader

Japan’s Fugaku Tops Global Supercomputing Rankings

June 22, 2020

A new Top500 champ was unveiled today. Supercomputer Fugaku, the pride of Japan and the namesake of Mount Fuji, vaulted to the top of the 55th edition of the To Read more…

By Tiffany Trader

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