Difference between revisions of "OpenMP in Small Bites/NUMA"

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OpenMP in Small Bites/NUMA
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    Why is it important to initialize your data in parallel when executing on a NUMA architecture? (Initializing the data in parallel distributes the date amoung the different sockets. When accessing the data in a hotspot region in the same pattern you avoid remote memory accesses.)
 
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    Why is it important to bind the threads? (Otherwise the operating system might decide to migrate the thread from one core to anothers. This results in a performance penalty due to the context switch and a potential remote data access on NUMA architectures.)
 
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    Given a NUMA architecture with to two sockets with six cores each: How can you place the threads of an OpenMP program running with 4 threads among both sockets and bind them to a core? (Set OMP_PROC_BIND=spread and OMP_PLACES=cores )
 

Revision as of 11:09, 2 November 2020



HPC.NRW
HPC.NRW
Other HPC Courses
1. Gprof Tutorial
2. Introduction to Linux in HPC
OpenMP in Small Bites
1. Overview
2. Worksharing
3. Data Scoping
4. Non-Uniform Memory Access







Video

Quiz

1. Why is it important to initialize your data in parallel when executing on a NUMA architecture?

Click and submit to see the answer

2. Why is it important to bind the threads?

Click and submit to see the answer

3. Given a NUMA architecture with to two sockets with six cores each: How can you place the threads of an OpenMP program running with 4 threads among both sockets and bind them to a core?

Click and submit to see the answer

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