Cray XC40 Optimization and Scaling Workshop

Enterprises & SME Research & Science
Cray XC40 Optimization and Scaling Workshop


Note: an additional course "Introduction to the Cray XC40 HPC System at HLRS" takes place on the previous day.

In August 2015, the Cray XC40 supercomputer Hornet at HLRS was upgraded to a new system named "Hazel Hen", featuring 7712 compute nodes, each equipped with two 12-core Intel Haswell processors running at 2.5 GHz. Each node is equipped with 128 GB DDR4 memory and connected to the other nodes through the Cray Aries network. The peak performance amounts to 7.4 PFlops.

In order to help users running efficiently on this new large system, HLRS and Cray offer this "Optimization and Scaling" workshop in addition to the "Introduction to the Cray XC40 HPC System at HLRS" Workshop taking place on the previous day. The intent of this workshop is to tune the performance of user codes by detecting, locating and solving bottlenecks.
By doing so, users can raise the volume as well as quality of their scientific findings while the costs (in terms of core hours) stay constant.

Target audience: Code owners of applications already running on Hazel Hen.


This is a "bring your own code" (BYOC) workshop. With support from CRAY and HLRS specialists, participants will enhance the efficiency of their application. In order to gain knowledge of and improve the application's behavior, profiling tools as well as optimization methods are discussed and exercised, both on simple examples and the actual user application. All categories of potential bottlenecks (CPU, memory subsystem, communication and I/O) will be addressed.

Besides intensive hands-on sessions, there will be lectures and discussions on:

  • profiling tools
  • node-level performance tuning
  • I/O (MPI-IO, NetCDF, HDF5)

Daily schedule

First day
9:00 -  9:30 Local registration
9:30 - 17:30 Course

2nd day
9:00 - 17:30 Course

Last day
9:00 - 16:30 Course

A detailed program can be found here.


In order to attend the workshop, you will have to bring your own code including a dataset that can be used at the scale of your current and maybe future production runs. You will be required to do some work on your application before the workshop (details will follow). In order to do so, you should already have an account on Hazel Hen and your application should already be able to run on the system. Information on access to Hazel Hen from Germany and Europe is available through this link.


Stefan Andersson, Michael Neff, and Mandes Schönherr (Cray)


via online registration form.


for registration is Oct. 9, 2016 (extended deadline).
Late registrations after the deadline are still possible but maybe with reduced quality of the handouts.


Members of German universities and public research institutes: none.
Members of universities and public research institutes within Europe or PRACE: 90 EUR.
Members of other universities and public research institutes: 90 EUR.
Others: 300 EUR.
(includes coffee breaks)


Travel Information and Accommodation

see our How to find us page.


HLRS is part of the Gauss Centre for Supercomputing (GCS), which is one of the six PRACE Advanced Training Centres (PATCs) that started in Feb. 2012.
HLRS is also member of the Baden-Württemberg initiative bwHPC-C5.
This course is provided within the framework of the bwHPC-C5 user Support. This course is not part of the PATC curriculum and is not sponsored by the PATC program.


Rolf Rabenseifner phone +49 711 685 65530,
Björn Dick phone +49 711 685 87189,
Joerg Hertzer phone +49 711 685 65932,

Shortcut-URL & Course Number