Credits to use KU Leuven infrastructure

KU Leuven uses a credit system to do accounting on the HPC systems it hosts. This is the case for its Tier-2 clusters, as well as the Tier-1 infrastructure.

Information on how to use the credit system can be found in the documentation on credit system basics.

How do I request credits on the KU Leuven Tier-2 systems

KU Leuven users

You can request two types of job credits: introduction credits and project credits.

Introduction credits

This is a limited amount of free credits for test and development purposes.

Project credits

These are job credits used for actual research and production runs.

You will find the relevant information to apply for both types of credits, including pricing, in the Service Catalog (login required).

UHasselt users

If you would like credits for a new project, please fill out the credit request form.


Please read and follow the instructions in that form carefully!

If you require additional credits for an existing project, please contact your VSC coordinator Geert Jan Bex.

Other users

Please contact your VSC coordinator/contact or your local support staff.

Job cost calculation

The cost of a job depends on the resources it consumes. Generally speaking, one credit buys the user one hour of walltime on one reference node. The resources that are taken into account to charge for a job are the walltime it consumed, and the number and type of compute nodes it ran on. The following formula is used:

0.000278 * nodes * walltime * nodetype


  • nodes is the number of compute nodes the job ran on;

  • walltime the effective duration of the job, expressed in seconds;

  • nodetype is the factor representing the node type’s performance as listed in the table below.

The Tier-2 cluster has several types of compute nodes, none of which is actually a reference node. The values for the different types are listed at the following links:

The difference in cost between different machines/processors reflects the performance difference between those types of nodes. The total cost of a job will typically be the same on any compute nodes, but the walltime will be different, depending on the performance of the nodes.

In the examples below, you run your jobs on a skylake node, for which we charge 10 credits per hour.

An example of a job running on multiple nodes and cores is given below:

$ qsub  -A lp_astrophysics_014  -l nodes=2:ppn=36:skylake  simulation_3415.pbs

If this job finished in 2.5 hours (i.e., walltime is 9000 seconds), the user will be charged:

0.000278 * 2 * 9000 * 10 = 50.0 credits

How do I get credits to use the Tier-1 infrastructure

Access to the Tier-1 is project-based, if you have a starting grant or an approved project, or you pay for your compute time, you should have received information on your job credits. If not, please contact support.