message passing interface a brief introduction
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Experts in numerical software andHigh Performance Computing
Message Passing Interfacea brief introduction
University of Birmingham
30th January 2017
Ning Li - Senior Technical Consultant
Sally Bridgwater – HPC Application Analyst
2High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
3High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
4High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
5High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
6High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
7High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
8High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
9High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
10High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
11High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
12High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
13High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
14High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
15High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
16High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
17High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
18High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
Best domain decomposition is dependent on algorithm.
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3rd party partitioning software often required
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A subset of processes responsible for each model
Atmospheric Model
Hydrology
Model
Ocean
Model
Land Surface Model
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From: source rankLetter # 1234 (tag)
To: destination rank
The message has:
A type - integer, real, etc.
A count
A location – memory address
Both source and destination
ranks need to provide these
Please send count number data of this type, located at memory address a on the source rank, to the destination rank and write to memory address b there.
22High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
23High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
24High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
25High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
26High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
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MPI_Recv()
MPI_Send()
Process 0
MPI_Recv()
MPI_Send()
Process 1
Tim
e
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MPI_Barrier
Tim
eT
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Root
10010110
0
10010110
2
10010110
1
10010110
Size-1
10010110
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Proc 0
01101
Proc 1
10101
Proc 2
11001
Proc 3
01011
Proc 4
11101
01101 10101 11001 01011 11101
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34High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
35High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
36High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
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Basic datatype
col_type: a derived datatype that is strided
row_type: a derived datatype that is contiguous
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40High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
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Rank=0
Coord=(0,0)
Rank=1
Coord=(0,1)
Rank=2
Coord=(0,2)
Rank=3
Coord=(1,0)
Rank=4
Coord=(1,1)
Rank=5
Coord=(1,2)
42High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
43High Performance Computing Consulting | Numerical Algorithms | Software Engineering Services | www.nag.com
Experts in High Performance Computing, Algorithms and Numerical Software Engineering
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