Communication in a Ring

Introduction
Problem Description
Programming Activity #2
Programming Activity #3

Introduction

In this exercise, we will perform straightforward communication using MPI. Communication in a ring involves sending to the next process rank, and receiving from the previous process rank.

Problem Description

You will implement a program that performs sending and receiving in a ring. You will use MPI_Send and MPI_Recv. Figure 2 shows an example of communication between \(p=6\) total process ranks.

Figure 2: example of ring communication, where there are \(p=6\) total ranks.

Programming Activity #2

Program the ring communication exercise described above. Note the following guidelines below.

Use and modify the starter file: ring_comm_starter.c.
Only use the MPI_Send and MPI_Recv primitives.
The program will take as input a variable number of process ranks. The program should work with \(p>1\) process ranks.
Each time a rank sends to its neighboring rank, the data should contain the sender’s process rank. E.g., rank 2 sends the integer value 2 to rank 3. And rank 3 sends integer value 3 to rank 4.
Each time you receive from your neighboring rank, add the value to a local counter. For instance, rank 2 will add 1 to its local counter once it receives the messsage from rank 1.
Each process rank should send and receive 10 times in total.
After each process has sent and received 10 times, the rank should output its value stored in the counter and exit gracefully.
Communication should begin with rank 0 sending to rank 1.
Q3: What does process rank 5’s counter store at the end of the computation?

Programming Activity #3