2022-06-22 Hybrid Programming in HPC - MPI+X (hhyp1s22)

Registration

Please register via https://events.prace-ri.eu/event/1334/

with your official e-mail address to prove your affiliation. Following your successful registration, you will receive further information approx. 1-2 weeks before the course.

Overview

Most HPC systems are clusters of shared memory nodes. To use such systems efficiently both memory consumption and communication time has to be optimized. Therefore, hybrid programming may combine the distributed memory parallelization on the node interconnect (e.g., with MPI) with the shared memory parallelization inside of each node (e.g., with OpenMP or MPI-3.0 shared memory). This course analyzes the strengths and weaknesses of several parallel programming models on clusters of SMP nodes. Multi-socket-multi-core systems in highly parallel environments are given special consideration. MPI-3.0 has introduced a new shared memory programming interface, which can be combined with inter-node MPI communication. It can be used for direct neighbor accesses similar to OpenMP or for direct halo copies, and enables new hybrid programming models. These models are compared with various hybrid MPI+OpenMP approaches and pure MPI. Numerous case studies and micro-benchmarks demonstrate the performance-related aspects of hybrid programming.

Hands-on sessions are included on all days. Tools for hybrid programming such as thread/process placement support and performance analysis are presented in a "how-to" section. This course provides scientific training in Computational Science and, in addition, the scientific exchange of the participants among themselves.

This online course is a PRACE training event. It is organised by LRZ in cooperation with NHR@FAU, HLRS and the VSC Research Center, TU Wien.

Preliminary Agenda

1st day

08:45   Join online
09:00      Welcome
09:05      Motivation
09:15      Introduction
09:30      Programming Models
09:35         - MPI + OpenMP
10:00            Practical (how to compile and start)
10:30   Break
10:45         - continue: MPI + OpenMP
11:30   Break
11:45         - continue: MPI + OpenMP
12:30            Practical (how to do pinning)
13:00   Lunch
14:00            Practical (hybrid through OpenMP parallelization)
15:30            Q & A, Discussion
16:00   End of first day

2nd day

08:45   Join online
09:00         - Overlapping Communication and Computation
09:30            Practical (taskloops)
10:30   Break
10:45         - MPI + OpenMP Conclusions
11:00         - MPI + Accelerators
11:30      Tools
11:45   Break
12:00      Programming Models (continued)
12:05         - MPI + MPI-3.0 Shared Memory
13:00   Lunch
14:00            Practical (replicated data)
15:30            Q & A, Discussion
16:00   End of second day

3rd day

08:45   Join online
09:00         - MPI Memory Models and Synchronization
09:40         - Pure MPI
10:00   Break
10:15         - Recap - MPI Virtual Topologies
10:45         - Topology Optimization
11:15   Break
11:30           Practical/Demo (application aware Cartesian topology)
12:30         - Topology Optimization (Wrap up)
12:45       Conclusions
13:00   Lunch
14:00       Finish the hands-on labs, Discussion, Q & A, Feedback
16:00   End of third day (course)

Prerequisites

Basic MPI and OpenMP knowledge. For the hands-on sessions you should know Unix/Linux and either C/C++ or Fortran.

Content Level

The content level of the course is broken down as:

Language

English

Lecturers

Dr. Claudia Blaas-Schenner (VSC Research Center, TU Wien), Dr. habil. Georg Hager (NHR@FAU), Dr. Rolf Rabenseifner (HLRS, Uni. Stuttgart)

Prices and Eligibility

The course is open and free of charge for people from academia and industry from the Member States (MS) of the European Union (EU) and Associated/Other Countries to the Horizon 2020 programme.