An Overview of ‘OpenACC for Programmers’ from the Book’s Editors

By Sunita Chandrasekaran and Guido Juckeland

June 20, 2018

In an era of multicore processors coupled with manycore accelerators in all kinds of devices from smartphones all the way to supercomputers, it is important to train current and future computational scientists of all domains the art of parallel programming. More and more colleges and universities have begun to integrate this as a mandatory course into their undergraduate computer science programs and also as an offer in the graduate/Ph.D. programs in computational science domains. In a time of rapidly evolving processor and accelerator architectures, the training material should have a longevity that lasts beyond next generation of hardware. As such more abstract programming models such as directive-based parallelization approaches offer both platform and performance portability and at the same time they also convey all the important concepts of parallel programming that can be easily transferred to other paradigms.

One such directive-based programming model is OpenACC, which has rapidly gained momentum over the past few years among scientific application users. OpenACC now accelerates ANSYS Fluent (CFD) and Gaussian (Quantum Chemistry) and VASP (Material Science), which are among the top 10 HPC applications, as well as selected ORNL Center for Accelerated Application Readiness (CAAR) codes to be run on the future CORAL Supercomputer: GTC (Physics), XGC (Physics), LSDalton (Quantum Chemistry), ACME(CWO), and FLASH (Astrophysics).

The book OpenACC for Programmers: Concepts and Strategies (published by Addison-Wesley Professional, September 20, 2017; edited by Sunita Chandrasekaran and Guido Juckeland) provides comprehensive and practical overviews of using the parallel programming model for heterogeneous computing systems. This book integrates contributions from 19 leading parallel programming experts from academia, public research organizations and industry. The text is written in a modular manner in a way that instructors can pick a chapter or chapters of their choice to include into their existing parallel programming curriculum. On the other hand, the book is comprehensive enough to be used for a tutorial or bootcamp on OpenACC. The chapters are stacked in a way that helps the reader to incrementally master the art of parallel programming. The editors have also built a GitHub course that is populated with example codes and chapters’ exercise solutions enabling instructors to create homework assignments.

The book begins its narrative on the basic concepts of OpenACC and the different types of parallelism exposed by the programming model in order to achieve performance without losing portability. One of the most important topics in parallel programming is profiling. How do you identify hot spots? How do you identify performance bottlenecks? Chapter 3 explains it all. This chapter demonstrates use of performance analysis tools, profilers and debugging tools such as the Nvidia profiler, Score-P & Vampir, TAU and Allinea’s DDT with nice visualization pictures for easy takeaways.

Are you new to OpenACC and keen to learn how to write your first program? Chapter 4 helps you take baby steps on how to build your first OpenACC program in both C and Fortran. This is a go-to chapter for a beginner learning to build and compile his/her code with the most commonly used OpenACC directives. The chapter also offers tips on how one can improve the code, serving as a mini best practice guide.

Do you want to know more about what happens under the hood? Look for Chapter 5 to read about what a compiler can and cannot do. The chapter concludes with some intriguing questions that could easily be converted into a class assignment or quiz.

Often, the scientific developers are looking for ways to incrementally improve performance. This leads to some fine tuning of the directives added to the code. Learning about some of the best practices can be quite useful in such scenario. Chapter 6 offers several do’s and don’t tips to the developers that often comes handy.

The book also has case studies demonstrating the usability of OpenACC on kernel as well as application benchmarks. Chapter 7 presents realistic examples where the authors from the Oak Ridge National Lab talk about a cosmology application, HACC, which is part of the CORAL benchmark suite. The authors discuss the performance portability of OpenACC directives across architectures.

To fulfill the goal of a general parallel programming training, the author of Chapter 8 highlights key features of several other approaches such as CUDA, OpenMP, OpenCL, C++ AMP, RAJA, Kokkos, TBB among others. This will give the readers a good understanding of additional parallel programming approaches and the mapping of the learned OpenACC constructs to them.

Are you looking to interoperate OpenACC with native or low-level APIs to program heterogeneous systems? Or interested to know more about how to program multiple devices available in order to maximize performance? Learn more in advanced chapters 9 and 10. Such discussions are very timely especially when we have supercomputers such as Summit where a single node consists of six Nvidia V100 cards per two Power9 CPUs.

Last but not the least, Chapters 11 and 12 can offer students and readers food for thought. A handful of authors who have provided support for OpenACC in research compilers such as OpenARC, XcalableACC, OpenUH and Sunway OpenACC narrate their experiences and share novel ideas of language extensions and optimizations. These ideas can help brainstorm how to enhance the language feature set of OpenACC, its compiler and runtime implementations for hardware architectures that are rapidly evolving.

With all this knowledge the readers are now well capable of developing their own parallel programs and, thus, fully utilizing all resources in a modern (heterogeneous) computing platform. In combination with the exercise questions at the end of each chapter, their solutions and code examples on GitHub, the book caters not only to both the “classical” educators and their students, but also to the domain scientists and practitioners. Parallel programming is such a fundamental skill that has grown beyond the traditional HPC community. High level programming approaches such as OpenACC provide a manageable learning curve for novices and this book is designed to be a guide on this journey.

Sunita Chandrasekaran is an assistant professor in Computer and Information Sciences and an affiliated faculty with the Center for Bioinformatics & Computational Biology (CBCB) at the University of Delaware. She has coauthored chapters in the books Programming Models for Parallel Computing, published by MIT Press, and Parallel Programming with OpenACC, published by Elsevier, 2016. Her research areas include exploring high-level programming models and its language extensions, building compiler and runtime implementations and validating and verifying implementations and their conformance to standard specifications. She is a member of the OpenMP, OpenACC, and SPEC HPG communities. Dr. Chandrasekaran earned her PhD in computer science engineering from Nanyang Technological University (NTU), Singapore, for creating a high-level software stacks for FPGAs.

Guido Juckeland founded the Computational Science Group at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Germany. He is responsible for designing and implementing end-to-end Research IT-workflows together with scientists and IT experts at HZDR. His research focuses on better usability and programmability for hardware accelerators and application performance monitoring as well as optimization. He is the vice-chair of the SPEC High Performance Group (HPG), an active member of the OpenACC technical and marketing committees, and also contributes to the OpenMP tools working group. Guido earned his PhD in computer science from Technische Universität Dresden, Germany, for his work on trace-based performance analysis for hardware accelerators.

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!

Data West Brings Technology Leaders to SDSC

December 6, 2018

Data and technology enthusiasts from around the world descended upon the San Diego Supercomputing Center (SDSC) for the third annual Data West conference, which is taking place this week on the campus of the University o Read more…

By Alex Woodie

Topology Can Help Us Find Patterns in Weather

December 6, 2018

Topology--–the study of shapes-- seems to be all the rage. You could even say that data has shape, and shape matters. Shapes are comfortable and familiar concepts, so it is intriguing to see that many applications are Read more…

By James Reinders

What’s New in HPC Research: Automatic Energy Efficiency, DNA Data Analysis, Post-Exascale & More

December 6, 2018

In this bimonthly feature, HPCwire highlights newly published research in the high-performance computing community and related domains. From exascale to quantum computing, the details are here. Read more…

By Oliver Peckham

HPE Extreme Performance Solutions

AI Can Be Scary. But Choosing the Wrong Partners Can Be Mortifying!

As you continue to dive deeper into AI, you will discover it is more than just deep learning. AI is an extremely complex set of machine learning, deep learning, reinforcement, and analytics algorithms with varying compute, storage, memory, and communications needs. Read more…

IBM Accelerated Insights

Five Steps to Building a Data Strategy for AI

Our data-centric world is driving many organizations to apply advanced analytics that use artificial intelligence (AI). AI provides intelligent answers to challenging business questions. AI also enables highly personalized user experiences, built when data scientists and analysts learn new information from data that would otherwise go undetected using traditional analytics methods. Read more…

Zettascale by 2035? China Thinks So

December 6, 2018

Exascale machines (of at least a 1 exaflops peak) are anticipated to arrive by around 2020, a few years behind original predictions; and given extreme-scale performance challenges are not getting any easier, it makes sense that researchers are already looking ahead to the next big 1,000x performance goal post: zettascale computing. Read more…

By Tiffany Trader

Topology Can Help Us Find Patterns in Weather

December 6, 2018

Topology--–the study of shapes-- seems to be all the rage. You could even say that data has shape, and shape matters. Shapes are comfortable and familiar conc Read more…

By James Reinders

Zettascale by 2035? China Thinks So

December 6, 2018

Exascale machines (of at least a 1 exaflops peak) are anticipated to arrive by around 2020, a few years behind original predictions; and given extreme-scale performance challenges are not getting any easier, it makes sense that researchers are already looking ahead to the next big 1,000x performance goal post: zettascale computing. Read more…

By Tiffany Trader

Robust Quantum Computers Still a Decade Away, Says Nat’l Academies Report

December 5, 2018

The National Academies of Science, Engineering, and Medicine yesterday released a report – Quantum Computing: Progress and Prospects – whose optimism about Read more…

By John Russell

Revisiting the 2008 Exascale Computing Study at SC18

November 29, 2018

A report published a decade ago conveyed the results of a study aimed at determining if it were possible to achieve 1000X the computational power of the the Read more…

By Scott Gibson

AWS Debuts Lustre as a Service, Accelerates Data Transfer

November 28, 2018

From the Amazon re:Invent main stage in Las Vegas today, Amazon Web Services CEO Andy Jassy introduced Amazon FSx for Lustre, citing a growing body of applicati Read more…

By Tiffany Trader

AWS Launches First Arm Cloud Instances

November 28, 2018

AWS, a macrocosm of the emerging high-performance technology landscape, wants to be everywhere you want to be and offer everything you want to use (or at least Read more…

By Doug Black

Move Over Lustre & Spectrum Scale – Here Comes BeeGFS?

November 26, 2018

Is BeeGFS – the parallel file system with European roots – on a path to compete with Lustre and Spectrum Scale worldwide in HPC environments? Frank Herold Read more…

By John Russell

DOE Under Secretary for Science Paul Dabbar Interviewed at SC18

November 21, 2018

During the 30th annual SC conference in Dallas last week, SC18 hosted U.S. Department of Energy Under Secretary for Science Paul M. Dabbar. In attendance Nov. 13-14, Dabbar delivered remarks at the Top500 panel, met with a number of industry stakeholders and toured the show floor. He also met with HPCwire for an interview, where we discussed the role of the DOE in advancing leadership computing. Read more…

By Tiffany Trader

Quantum Computing Will Never Work

November 27, 2018

Amid the gush of money and enthusiastic predictions being thrown at quantum computing comes a proposed cold shower in the form of an essay by physicist Mikhail Read more…

By John Russell

Cray Unveils Shasta, Lands NERSC-9 Contract

October 30, 2018

Cray revealed today the details of its next-gen supercomputing architecture, Shasta, selected to be the next flagship system at NERSC. We've known of the code-name "Shasta" since the Argonne slice of the CORAL project was announced in 2015 and although the details of that plan have changed considerably, Cray didn't slow down its timeline for Shasta. Read more…

By Tiffany Trader

IBM at Hot Chips: What’s Next for Power

August 23, 2018

With processor, memory and networking technologies all racing to fill in for an ailing Moore’s law, the era of the heterogeneous datacenter is well underway, Read more…

By Tiffany Trader

House Passes $1.275B National Quantum Initiative

September 17, 2018

Last Thursday the U.S. House of Representatives passed the National Quantum Initiative Act (NQIA) intended to accelerate quantum computing research and developm Read more…

By John Russell

CERN Project Sees Orders-of-Magnitude Speedup with AI Approach

August 14, 2018

An award-winning effort at CERN has demonstrated potential to significantly change how the physics based modeling and simulation communities view machine learni Read more…

By Rob Farber

Summit Supercomputer is Already Making its Mark on Science

September 20, 2018

Summit, now the fastest supercomputer in the world, is quickly making its mark in science – five of the six finalists just announced for the prestigious 2018 Read more…

By John Russell

AMD Sets Up for Epyc Epoch

November 16, 2018

It’s been a good two weeks, AMD’s Gary Silcott and Andy Parma told me on the last day of SC18 in Dallas at the restaurant where we met to discuss their show news and recent successes. Heck, it’s been a good year. Read more…

By Tiffany Trader

US Leads Supercomputing with #1, #2 Systems & Petascale Arm

November 12, 2018

The 31st Supercomputing Conference (SC) - commemorating 30 years since the first Supercomputing in 1988 - kicked off in Dallas yesterday, taking over the Kay Ba Read more…

By Tiffany Trader

Leading Solution Providers

SC 18 Virtual Booth Video Tour

Advania @ SC18 AMD @ SC18
ASRock Rack @ SC18
DDN Storage @ SC18
HPE @ SC18
IBM @ SC18
Lenovo @ SC18 Mellanox Technologies @ SC18
One Stop Systems @ SC18
Oracle @ SC18 Panasas @ SC18
Supermicro @ SC18 SUSE @ SC18 TYAN @ SC18
Verne Global @ SC18

TACC’s ‘Frontera’ Supercomputer Expands Horizon for Extreme-Scale Science

August 29, 2018

The National Science Foundation and the Texas Advanced Computing Center announced today that a new system, called Frontera, will overtake Stampede 2 as the fast Read more…

By Tiffany Trader

HPE No. 1, IBM Surges, in ‘Bucking Bronco’ High Performance Server Market

September 27, 2018

Riding healthy U.S. and global economies, strong demand for AI-capable hardware and other tailwind trends, the high performance computing server market jumped 28 percent in the second quarter 2018 to $3.7 billion, up from $2.9 billion for the same period last year, according to industry analyst firm Hyperion Research. Read more…

By Doug Black

Nvidia’s Jensen Huang Delivers Vision for the New HPC

November 14, 2018

For nearly two hours on Monday at SC18, Jensen Huang, CEO of Nvidia, presented his expansive view of the future of HPC (and computing in general) as only he can do. Animated. Backstopped by a stream of data charts, product photos, and even a beautiful image of supernovae... Read more…

By John Russell

Germany Celebrates Launch of Two Fastest Supercomputers

September 26, 2018

The new high-performance computer SuperMUC-NG at the Leibniz Supercomputing Center (LRZ) in Garching is the fastest computer in Germany and one of the fastest i Read more…

By Tiffany Trader

Houston to Field Massive, ‘Geophysically Configured’ Cloud Supercomputer

October 11, 2018

Based on some news stories out today, one might get the impression that the next system to crack number one on the Top500 would be an industrial oil and gas mon Read more…

By Tiffany Trader

Intel Confirms 48-Core Cascade Lake-AP for 2019

November 4, 2018

As part of the run-up to SC18, taking place in Dallas next week (Nov. 11-16), Intel is doling out info on its next-gen Cascade Lake family of Xeon processors, specifically the “Advanced Processor” version (Cascade Lake-AP), architected for high-performance computing, artificial intelligence and infrastructure-as-a-service workloads. Read more…

By Tiffany Trader

Google Releases Machine Learning “What-If” Analysis Tool

September 12, 2018

Training machine learning models has long been time-consuming process. Yesterday, Google released a “What-If Tool” for probing how data point changes affect a model’s prediction. The new tool is being launched as a new feature of the open source TensorBoard web application... Read more…

By John Russell

The Convergence of Big Data and Extreme-Scale HPC

August 31, 2018

As we are heading towards extreme-scale HPC coupled with data intensive analytics like machine learning, the necessary integration of big data and HPC is a curr Read more…

By Rob Farber

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