Ruud van der Pas

Senior Principal Software Engineer, Oracle Linux Engineering. The Netherlands.

“Staying Close to Home with NUMA“

18 February 2025

Abstract

In the not so distant past, a Non-Uniform Memory Access (or NUMA for short) memory architecture was only used in very large servers. Tuning applications for NUMA was therefore only for a relatively small group to worry about.

Today’s situation is drastically different. Already a 2 socket server has a NUMA architecture. It has even come down to the socket level, because certain processors have a NUMA memory architecture internally.

The performance cost of neglecting the NUMA architecture ranges from noticeable to dramatic.

This talk starts with a description of NUMA. This includes the benefits, because there are good reasons to use a NUMA architecture. Next, some common techniques how to tune for NUMA, and the choices to be made, are introduced and explained. We end with quite a compelling performance example.

Bio

Ruud is a Senior Principal Software Engineer in the Oracle Linux and Virtualization engineering organization at Oracle Corporation.

He operates on a world-wide basis. His key area of expertise is in parallel computing, in particular on shared memory systems using OpenMP. He has been involved with OpenMP from the start and has extensive experience in highly scalable shared memory performance on various types of algorithms, including graph analysis.

He also regularly gives technical presentations and tutorials at conferences and workshops.

Ruud has studied mathematics and physics and has been involved with the performance of technical applications for 25+ years. Before joining Oracle he worked at Sun Microsystems, SGI, Convex Computer Corporation, the University of Utrecht and Phillips.

He is also a board member of IDC’s HPC Advisory Committee, regularly receives invitations to be on the program committee of international conferences and has a strong interest in Interval Analysis and Interval Arithmetic.

Ruud’s current area of interest is the gprofng application profiling tool that is part of the GNU binutils tool suite. In addition to his code development work, he is actively involved with the promotion of this tool, including giving presentations.

Ruud has published over 20 conference papers related to application tuning and parallelization, several technical white papers and is co-author of the books “Using OpenMP”, and “Using OpenMP – The Next Step”, both published by MIT Press.

MW25 Slides