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Hands-on: Collective operations

In this exercise we test different routines for collective communication.
In this exercise we test different routines for collective communication.

Source code for this exercise is located in mpi/collectives/

First, write a program where rank 0 sends an array containing numbers from 0
to 7 to all the other ranks using collective communication.

Next, we continue with four MPI tasks with following initial data vectors:

                 
Task 0: 0 1 2 3 4 5 6 7
Task 1: 8 9 10 11 12 13 14 15
Task 2: 16 17 18 19 20 21 22 23
Task 3: 24 25 26 27 28 29 30 31

In addition, each task has a receive buffer for eight elements and the values
in the buffer are initialized to -1. Implement a program that sends and
receives values from the data vectors to receive buffers using a single
collective communication routine for each case, so that the receive buffers
will have the following values. You can start from the skeleton file
skeleton.py.

Case 1

                 
Task 0: 0 1 -1 -1 -1 -1 -1 -1
Task 1: 2 3 -1 -1 -1 -1 -1 -1
Task 2: 4 5 -1 -1 -1 -1 -1 -1
Task 3: 6 7 -1 -1 -1 -1 -1 -1

Case 2

                 
Task 0: -1 -1 -1 -1 -1 -1 -1 -1
Task 1: 0 1 8 9 16 17 24 25
Task 2: -1 -1 -1 -1 -1 -1 -1 -1
Task 3: -1 -1 -1 -1 -1 -1 -1 -1

Case 3

                 
Task 0: 8 10 12 14 16 18 20 22
Task 1: -1 -1 -1 -1 -1 -1 -1 -1
Task 2: 40 42 44 46 48 50 52 54
Task 3: -1 -1 -1 -1 -1 -1 -1 -1

Tip: create two communicators

© CSC - IT Center for Science Ltd.
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Python in High Performance Computing

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