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!

TACC Researchers Test AI Traffic Monitoring Tool in Austin

December 13, 2017

Traffic jams and mishaps are often painful and sometimes dangerous facts of life. At this week’s IEEE International Conference on Big Data being held in Boston, researchers from TACC and colleagues will present a new Read more…

AMD Wins Another: Baidu to Deploy EPYC on Single Socket Servers

December 13, 2017

When AMD introduced its EPYC chip line in June, the company said a portion of the line was specifically designed to re-invigorate a single socket segment in what has become an overwhelmingly two-socket landscape in the d Read more…

By John Russell

Microsoft Wants to Speed Quantum Development

December 12, 2017

Quantum computing continues to make headlines in what remains of 2017 as tech giants jockey to establish a pole position in the race toward commercialization of quantum. This week, Microsoft took the next step in advanci Read more…

By Tiffany Trader

HPE Extreme Performance Solutions

Explore the Origins of Space with COSMOS and Memory-Driven Computing

From the formation of black holes to the origins of space, data is the key to unlocking the secrets of the early universe. Read more…

ESnet Now Moving More Than 1 Petabyte/wk

December 12, 2017

Optimizing ESnet (Energy Sciences Network), the world's fastest network for science, is an ongoing process. Recently a two-year collaboration by ESnet users – the Petascale DTN Project – achieved its ambitious goal t Read more…

AMD Wins Another: Baidu to Deploy EPYC on Single Socket Servers

December 13, 2017

When AMD introduced its EPYC chip line in June, the company said a portion of the line was specifically designed to re-invigorate a single socket segment in wha Read more…

By John Russell

Microsoft Wants to Speed Quantum Development

December 12, 2017

Quantum computing continues to make headlines in what remains of 2017 as tech giants jockey to establish a pole position in the race toward commercialization of Read more…

By Tiffany Trader

HPC Iron, Soft, Data, People – It Takes an Ecosystem!

December 11, 2017

Cutting edge advanced computing hardware (aka big iron) does not stand by itself. These computers are the pinnacle of a myriad of technologies that must be care Read more…

By Alex R. Larzelere

IBM Begins Power9 Rollout with Backing from DOE, Google

December 6, 2017

After over a year of buildup, IBM is unveiling its first Power9 system based on the same architecture as the Department of Energy CORAL supercomputers, Summit a Read more…

By Tiffany Trader

Microsoft Spins Cycle Computing into Core Azure Product

December 5, 2017

Last August, cloud giant Microsoft acquired HPC cloud orchestration pioneer Cycle Computing. Since then the focus has been on integrating Cycle’s organization Read more…

By John Russell

GlobalFoundries, Ayar Labs Team Up to Commercialize Optical I/O

December 4, 2017

GlobalFoundries (GF) and Ayar Labs, a startup focused on using light, instead of electricity, to transfer data between chips, today announced they've entered in Read more…

By Tiffany Trader

HPE In-Memory Platform Comes to COSMOS

November 30, 2017

Hewlett Packard Enterprise is on a mission to accelerate space research. In August, it sent the first commercial-off-the-shelf HPC system into space for testing Read more…

By Tiffany Trader

SC17 Cluster Competition: Who Won and Why? Results Analyzed and Over-Analyzed

November 28, 2017

Everyone by now knows that Nanyang Technological University of Singapore (NTU) took home the highest LINPACK Award and the Overall Championship from the recently concluded SC17 Student Cluster Competition. We also already know how the teams did in the Highest LINPACK and Highest HPCG competitions, with Nanyang grabbing bragging rights for both benchmarks. Read more…

By Dan Olds

US Coalesces Plans for First Exascale Supercomputer: Aurora in 2021

September 27, 2017

At the Advanced Scientific Computing Advisory Committee (ASCAC) meeting, in Arlington, Va., yesterday (Sept. 26), it was revealed that the "Aurora" supercompute Read more…

By Tiffany Trader

NERSC Scales Scientific Deep Learning to 15 Petaflops

August 28, 2017

A collaborative effort between Intel, NERSC and Stanford has delivered the first 15-petaflops deep learning software running on HPC platforms and is, according Read more…

By Rob Farber

Oracle Layoffs Reportedly Hit SPARC and Solaris Hard

September 7, 2017

Oracle’s latest layoffs have many wondering if this is the end of the line for the SPARC processor and Solaris OS development. As reported by multiple sources Read more…

By John Russell

AMD Showcases Growing Portfolio of EPYC and Radeon-based Systems at SC17

November 13, 2017

AMD’s charge back into HPC and the datacenter is on full display at SC17. Having launched the EPYC processor line in June along with its MI25 GPU the focus he Read more…

By John Russell

Nvidia Responds to Google TPU Benchmarking

April 10, 2017

Nvidia highlights strengths of its newest GPU silicon in response to Google's report on the performance and energy advantages of its custom tensor processor. Read more…

By Tiffany Trader

Japan Unveils Quantum Neural Network

November 22, 2017

The U.S. and China are leading the race toward productive quantum computing, but it's early enough that ultimate leadership is still something of an open questi Read more…

By Tiffany Trader

GlobalFoundries Puts Wind in AMD’s Sails with 12nm FinFET

September 24, 2017

From its annual tech conference last week (Sept. 20), where GlobalFoundries welcomed more than 600 semiconductor professionals (reaching the Santa Clara venue Read more…

By Tiffany Trader

Google Releases Deeplearn.js to Further Democratize Machine Learning

August 17, 2017

Spreading the use of machine learning tools is one of the goals of Google’s PAIR (People + AI Research) initiative, which was introduced in early July. Last w Read more…

By John Russell

Leading Solution Providers

Amazon Debuts New AMD-based GPU Instances for Graphics Acceleration

September 12, 2017

Last week Amazon Web Services (AWS) streaming service, AppStream 2.0, introduced a new GPU instance called Graphics Design intended to accelerate graphics. The Read more…

By John Russell

Perspective: What Really Happened at SC17?

November 22, 2017

SC is over. Now comes the myriad of follow-ups. Inboxes are filled with templated emails from vendors and other exhibitors hoping to win a place in the post-SC thinking of booth visitors. Attendees of tutorials, workshops and other technical sessions will be inundated with requests for feedback. Read more…

By Andrew Jones

EU Funds 20 Million Euro ARM+FPGA Exascale Project

September 7, 2017

At the Barcelona Supercomputer Centre on Wednesday (Sept. 6), 16 partners gathered to launch the EuroEXA project, which invests €20 million over three-and-a-half years into exascale-focused research and development. Led by the Horizon 2020 program, EuroEXA picks up the banner of a triad of partner projects — ExaNeSt, EcoScale and ExaNoDe — building on their work... Read more…

By Tiffany Trader

Delays, Smoke, Records & Markets – A Candid Conversation with Cray CEO Peter Ungaro

October 5, 2017

Earlier this month, Tom Tabor, publisher of HPCwire and I had a very personal conversation with Cray CEO Peter Ungaro. Cray has been on something of a Cinderell Read more…

By Tiffany Trader & Tom Tabor

IBM Begins Power9 Rollout with Backing from DOE, Google

December 6, 2017

After over a year of buildup, IBM is unveiling its first Power9 system based on the same architecture as the Department of Energy CORAL supercomputers, Summit a Read more…

By Tiffany Trader

Tensors Come of Age: Why the AI Revolution Will Help HPC

November 13, 2017

Thirty years ago, parallel computing was coming of age. A bitter battle began between stalwart vector computing supporters and advocates of various approaches to parallel computing. IBM skeptic Alan Karp, reacting to announcements of nCUBE’s 1024-microprocessor system and Thinking Machines’ 65,536-element array, made a public $100 wager that no one could get a parallel speedup of over 200 on real HPC workloads. Read more…

By John Gustafson & Lenore Mullin

Flipping the Flops and Reading the Top500 Tea Leaves

November 13, 2017

The 50th edition of the Top500 list, the biannual publication of the world’s fastest supercomputers based on public Linpack benchmarking results, was released Read more…

By Tiffany Trader

Intel Launches Software Tools to Ease FPGA Programming

September 5, 2017

Field Programmable Gate Arrays (FPGAs) have a reputation for being difficult to program, requiring expertise in specialty languages, like Verilog or VHDL. Easin Read more…

By Tiffany Trader

  • arrow
  • Click Here for More Headlines
  • arrow
Share This