Description
This course covers performance engineering approaches on the compute
node level. Even application developers who are fluent in OpenMP and MPI
often lack a good grasp of how much performance could at best be
achieved by their code. This is because parallelism takes us only half
the way to good performance. Even worse, slow serial code tends to scale
very well, hiding the fact that resources are wasted. This course
conveys the required knowledge to develop a thorough understanding of
the interactions between software and hardware. This process must start
at the core, socket, and node level, where the code gets executed that
does the actual computational work. We introduce the basic architectural
features and bottlenecks of modern processors and compute nodes.
Pipelining, SIMD, superscalarity, caches, memory interfaces, ccNUMA,
etc., are covered. A cornerstone of node-level performance analysis is
the Roofline model, which is introduced in due detail and applied to
various examples from computational science. We also show how simple
software tools can be used to acquire knowledge about the system, run
code in a reproducible way, and validate hypotheses about resource
consumption. Finally, once the architectural requirements of a code are
understood and correlated with performance measurements, the potential
benefit of code changes can often be predicted, replacing
hope-for-the-best optimizations by a scientific process.
This course provides –via lectures, demos, and hands-on labs– scientific training in Computational Science, and in addition, the scientific exchange of the participants among themselves.
This course is organized by the Vienna Scientific Cluster (VSC).
Content:
Introduction
Tools topology & affinity in multicore environments
Microbenchmarking for architectural exploration
Roofline model: basics
Tools: hardware performance counters
Roofline case studies
Optimal use of parallel resources
Extending Roofline: The ECM performance model
Lecturers:
Georg Hager and
Gerhard Wellein (
RRZE /
HPC, University of Erlangen-Nürnberg and NHR@FAU)
Language:
English
Date, Time, and Location:
March 10-12, 2021, 9am - 5pm,
Online course via Zoom