3 days of code, coffee, & GPUs

The first DiRAC hackathon took place on the 9th of September 2018 at Swansea University. The event gave DiRAC users an opportunity to explore the potential of GPU’s to push their science to the next level of parallel computing. Several teams of explorers set off on their GPU adventure, aided by GPU trainer Wayne Gaudin from PGI Compilers and tools (Dev Tech) sponsored by Nvidia, and supported by Dr Ed Bennett from Swansea University, and Dr Jeffrey Salmond from Cambridge University.

The Teams gather

The event was hosted by Swansea and facilitated by the DiRAC GPU systems hosted by Cambridge. DiRAC has 11 GPU machines which are free to use subject to a scientific project approval. The GPU system comprises 11 nodes each containing 4 NVIDIA Tesla P100 GPUs. The NVIDIA Pascal architecture enables the Tesla P100 to deliver superior performance for HPC and hyperscale workloads. With more than 21 teraFLOPS of 16-bit floating-point (FP16) performance, Pascal is optimized to drive exciting new possibilities in deep learning applications. Pascal also delivers over 5 and 10 teraFLOPS of double- and single-precision performance for HPC workloads.

Hardware was not the only thing offered by DiRAC & Swansea, expertise was also in abundance, in the form of RSEs like Dr Mark Dawson, Dr Michele Mesiti, Dr Jarno Rantaharju, and Dr Chennakesava from Swansea, from DiRAC Cambridge Dr Jeffrey Salmond and Matt Archer along with Matthias Wagner from Nvidia.

Passionate Projects

Hackathons are a place where ideas mix and in September there was a great mix with the AREPO, CURSE, FARGO, GRID, TROVE and The Mighty Atom codes to work on. The users came together to share ideas, experience, and develop good practice, but most of all to see if GPUs would be a good fit for their research. There were teams from all across the UK, including Swansea University, University of Edinburgh, University of Cambridge and the UK Atomic Energy Authority.

With all these different areas of expertise, the teams came together on a cool morning in September.

How the day went

With all local participants staying on site, the event started bright and early on Sunday the 9th of September. Gathering in the Wallace Building, introductions were made and objectives set for the 3 day GPU Hackathon journey.

With the base knowledge of CUDA & openACC , two free courses from Nvidia, and re-enforced by Wayne all the teams started their first steps into the world of GPUs.

After a productive day with most groups successfully running their code on the GPU systems, everyone relaxed and discussed the day’s trials and triumphs over a pizza at Brewstone

Pizza at Brewstone

Monday was another 9am start, and with fruits, cakes and coffee the GPU experience was continued.

In the evening the weary travellers relaxed in the award winning luxurious boutique style hotel Morgans, where the exotic idea for GPUs mixed with the spices, and aromas of the beautifully prepared food, situated in a relaxed and unstuffy environment. With the aid of sweet desserts and a small amount of alcohol, the thought of what had been achieved and what was still to do dominated the conversations.

On the last day, with heads down and gritted determination, everyone focused on the final push to achieve each team’s goal. This was not the focus of the lone worker, but the focus of a well trained team, working together, looking out for each other and supporting each other. This support was also given between teams and was not just apparent on the last day, but was a continuous theme of the whole 3-day hackathon. 

Interaction between teams
Swansea in the foreground & interaction between Cambridge & Edinburgh in the background

In the afternoon of the last day all the teams gathered to present their achievement over the 3 days, highlighting problems, solutions found, and an expectation of where this would advance their research to in the future, and prepare them for the machines of the future.

On the last evening there was a celebration of what was achieved, not a big fanfare, but a relaxed quiet reflection of a job well done. DiRAC’s Director, Dr Mark Wilkinson was there to welcome the teams, gauge their reaction to this first DiRAC Hackathon, and assess interest in GPUs possibly playing a bigger part in the upcoming DiRAC3 systems.

Neurons and Cores

This hackathon was not just for the ‘knowledgable’ ones, but also for the ‘I’ve done a bit’ ones, and the ‘would like to know more’ ones. They all came with open minds and a very basic knowledge about GPUs. All participants stated that they would recommend the pre-requisite online training provided by NVidia, there are some comments:

The online material was great introduction, that gave us an idea of some of the key issues


Very useful, everthing well explained & liked interactive aspect

At the end of the 3 days great strides had been achieved by all the teams see the results by visiting the team pages. All teams agreed that the 3 day GPU event will have a positive impact on their research.

Looking to the Future

The hackathon was a great success, and apparently the teams agreed, with all participants stating that they would expect to use what they learnt in the future, and everyone reporting the hackathon was a good or very good event, with comments like:

“Great experience, learned a lot”, “it was good fun”, and “GREAT FUN! GOOD EXPERIENCE!”

We attended DiRAC’s “Nvidia GPU Hackathon” with limited knowledge  — and almost no practical experience — of accelerating codes using GPUs. The training material provided by Nvidia gave us a broad view of using CUDA and OpenACC to achieve speed-ups using GPU hardware, but we really got to grips with it at the hackathon by getting stuck in and modifying code ourselves. Our goals were to gain some experience, and to try to speed-up a ray-tracing module used in the cosmological hydrodynamics code AREPO. Using OpenACC directives and PGI’s compiler, we eventually managed to gain a ~10x acceleration with a single GPU, compared to both single & multi CPU only runs. Alongside this acceleration we also gained an appreciation for the algorithmic regimes where GPUs are useful, and the important technical considerations associated with GPU programming. Since the hackathon we have put our new knowledge to use, modifying other codes to take advantage of GPU acceleration!”

Lewis H. Weinberger

After the success of the GPU hackathon, DiRAC will hold more of these events. DiRAC is here for the advancement of science, and to help you get your research to the next level. In the future there will be hackathons on different topics around the country. The next one is exploring ARM technology,  Febuary 2019.

Watch this space for training, tweets and hackathons