OpenMP at SC15

In my previous blog post I stated that OpenMP 4.5 is on it’s way and scheduled for a release during SC15. If you are interested in learning about OpenMP, SC15 can be a great opportunity. This blog post points out all the related activities that I have been made aware of.

Tutorials on Sunday and Monday

On Sunday the full-day tutorial A Hands-On Introduction to OpenMP will take place, covering the core features of OpenMP 4.0. On Monday, there will be the full-day tutorial Advanced OpenMP: Performance and 4.1 Features (we did not expect the name change at the time of the submission) which basically continues from the introductory tutorial and concentrates on getting performance from OpenMP codes as well as it discusses language features introduced with OpenMP 3.x and 4.x in-depth. In addition to those two tutorials with a focus on programming, the half-day tutorial Debugging & Performance Tools for MPI and OpenMP 4.0 APIs provides exploration of parallel debugging and optimization focused on techniques that can be used with accelerators and coprocessors.

The OpenMP BoF

This year’s BoF is titled OpenMP: Where Are We, and What’s Next?. I think that is a reasonable question to ask at this point. The BoF will take place on Tuesday 5:30 – 7:00 pm in room 291. From the description: Experts will give short presentations on key OpenMP 4.1 features and answer your technical questions. OpenMP CEO Michael Wong will present our vision for OpenMP 5.0 and we’ll finish with an audience-led discussion with a panel including members of the OpenMP ARB.

The OpenMP Booth and Booth Talks

As in previous years the OpenMP organization has its own booth, which is number #2036. Most important, every day from 4 pm to 6 pm there will be free beer (while supply lasts), and with that the opportunity to talk to OpenMP folks in person. There are also a couple of talks scheduled to take place right at the OpenMP booth, which will be recorded and published online:

  • Power Optimization Strategies in OpenMP, on Tuesday 11:15 – 11:40 am, by A. Malik (University of Houston),
  • OpenMP and the Multicore Association (MCA), on Tuesday 2:15 to 2:40 pm, by S. Chandrasekaran (University of Delaware),
  • Getting OpenMP up to Speed, on Wednesday 11:15 – 11:40 pm, by R. van der Pas (Oracle),
  • OpenMP Tasking, on Wednesday 2:15 to 2:40 pm, by M. Klemm (Intel) and C. Terboven (RWTH Aachen University),
  • Parallelware and OpenMP, on Thursday 11:15 – 11:40 pm, by M. Arenaz (Appentra).

SC14 Video: A Short Stroll Through OpenMP 4.0

During SC14, Michael Klemm from Intel and myself teamed up to give an OpenMP 4.0 overview talk at the OpenMP booth. Our goal was to touch on all important aspects, from thread binding over tasking to accelerator support, and to entertain our audience in doing so. Although not all jokes translate from German to English as we intended, I absolutely think that the resulting video is a fun-oriented 25-minutes run-down of OpenMP 4.0 and worth sharing here:

New article on OpenMP 4.0 online

A while ago I published a list with articles and tutorials on OpenMP 4.0, including the German article on heise Developer I wrote together with Michael Klemm (Intel). A slightly modified English version of our text now appeared in issue 16 of Intel’s Parallel Universe magazine, titled Full throttle: OpenMP 4.0.

The current issue and also past issues of the Parallel Universe magazine are available at If you are interested in developing parallel code for Intel architectures you might find some interesting reads over there.

OpenMP 4.0 almost ready after recent F2F meeting

Last week’s OpenMP Language Committee face-to-face (F2F) meeting was meant to resolve the final outstanding issues to get the OpenMP 4.0 specification ready. With this week’s concall I assume we achieved just that and now it is our editor’s turn to apply all remaining tickets to the spec document. After that, the OpenMP ARB will perform the official vote on July 11th (if my calendar is correct), which in case of a positive vote will then also be the release date of the OpenMP 4.0 spec. This voting is generally considered just a formality, as the OpenMP member companies and institutions sending staff to the Language Committee also constitute the OpenMP ARB. OpenMP 4.0 will not break existing codes.

If you are interested in learning about the new features, you may want to stop by at the JARA-HPC booth #755 at ISC in Leipzig next week. We have (preliminary) OpenMP 4.0 syntax reference cards as handouts for you. If you want to meet me in person, you are welcome to visit the booth during my booth duties on Monday (11:30h to 13:00h), Tuesday (11:30 to 13:00h) or Wednesday (13:00h to 14:30h).

Advanced OpenMP Tutorial @ ISC in June in Leipzig

The International Supercomputing Conference (ISC) will take place in Leipzig, Germany, next week from June 16th to June 20th, 2013. This year the program contains tutorials again and the team of Bronis de Supinski (LLNL), Michael Klemm (Intel) and myself will offer the Advanced OpenMP Programming tutorial on June 16th, 9:00 AM to 1:00 PM. If you are interested in learning about performance-focused OpenMP programming and the new features in OpenMP 4.0, this might be the right one for you, although we obviously cannot cover everything in detail in just the 4 hours we got. We asked for a full day, but got only a half one.

While we quickly review the basics of OpenMP programming, we assume attendees understand basic parallelization concepts and will easily grasp those basics. We focus on performance aspects, such as data and thread locality on NUMA architectures, false sharing, and exploitation of SIMD vector units. We discuss language features in-depth, with emphasis on features recently added to OpenMP such as tasking. We close with an overview of the new OpenMP 4.0 directives for attached compute accelerators. This is our detailed agenda:

  1. OpenMP Overview (15 minutes)
    1. Core Concepts: Parallel Region, Worksharing, Nesting
    2. Synchronization: Synchronization Constructs and the Memory Model
  2. Techniques to Obtain High Performance with OpenMP: Memory Access (45 minutes)
    1. Understanding Memory Access Patterns
    2. Memory Placement and Thread Binding
    3. Performance Tips and Tricks: Avoiding False Sharing, Private versus Shared Data
  3. Techniques to Obtain High Performance with OpenMP: Vectorization (30 minutes)
    1. Understanding Vector Microarchitectures
    2. Vectorization with OpenMP 4.0
  4. Advanced Language features (60 minutes)
    1. The OpenMP Tasking Model
    2. Tasking in Detail: Final, Mergeable, and Dependencies
    3. Cancellation
    4. Misc. OpenMP 4.0 Features: Controlling the Implementation, Reduction Extensions, Improved Atomic Support
  5. OpenMP for Attached Compute Accelerators (45 minutes)
    1. The OpenMP Execution Model for Devices
    2. Target Construct
    3. OpenMP on the Intel Xeon Phi Coprocessor Examples
  6. 6. Future OpenMP Directions (15 minutes)
    1. Comprehensive OpenMP new Features Overview
    2. OpenMP 4.0 and beyond Status, Directions and Schedule
    3. Open Discussion of Possible OpenMP Extensions (until we got thrown out of the room or people have left for lunch)

OpenMP 4.0 RC2 has been released

In addition to the new features already present in release candidate one (RC1), the second draft of the next OpenMP specification release contains the following additions (quoted from

  • Initial accelerators support: Device Data Environments (p16), target constructs (p68: target, target data, target update, declare target, teams, distribute; p151: map clause; and associated runtime routines (p191).)
  • Task dependency support through the new depend clause. (p91)
  • Initial error model support through cancel and cancellation point constructs to request cancellation of specified region types and to declare a user-defined cancellation point to  check for cancellation requests. (Section 2.13, p116: Cancellation Constructs)
  • Support for array sections in C, C++ and Fortran. (Section 2.4, p36: Array Sections)
  • Extended declare simd directive to allow multiple declarations. (p64)
  • New environment variable OMP_DISPLAY_ENV instructing the runtime to display the OpenMP version number and ICV values during initialization. (p219)
  • Additional enhancements to support Fortran 2003.

As we were not yet able to incorporate all the feedback that has been reported so far, a few know issues are still in the document. Additionally, some more minor changes are already in preparation. Feedback and questions are of course still welcomed, so head over to and download the new document.