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Exercises

The laboratory skeleton is available here.

  • Exercise 1: Implement the ring algorithm using MPI, where the process with ID 0 sends a random number to process 1 (its neighbor), and then the other nodes receive the number from the previous process, increment it by 2, and send it to the next process (for example, process 2 receives the value from process 1, increments it, and sends it further to process 3), all ending when the value reaches process 0. For each process, you should display its rank and the received value.
  • Exercise 2: Implement an MPI program where process 0 sends a randomly generated value to the other processes using MPI_Bcast. Note: Do not use MPI_Recv.
  • Exercise 3: Implement an MPI program with N processes, where process 0 initializes an array of size 5 * N with 0, divides it (the chunk size is 5, defined in the skeleton), and sends it to all processes using MPI_Scatter. The processes will add each element received with their rank, and then they will send the arrays they operated on, along with their ranks, to process 0 using MPI_Gather. Process 0 will subsequently display the result array from MPI_Gather.
  • Exercise 4: Implement an MPI program with 4 processes, where 3 processes send a value to the fourth process, which will receive the value using MPI_ANY_SOURCE and display the received value and the source process's rank using MPI_SOURCE from MPI_Status (status from MPI_Recv).
tip

MPI_ANY_SOURCE is used instead of the source process's rank in MPI_Recv, indicating that the receiving process can receive a message from any process.

  • Exercise 5: Implement an MPI program with 2 processes, where process 0 sends 10 values with different tags to process 1, and process 1 receives the values using the MPI_ANY_TAG parameter in MPI_Recv. Display the received value along with its tag using MPI_Status (status from MPI_Recv).
tip

MPI_ANY_TAG is used instead of the message tag in MPI_Recv, indicating that it can receive any message from the source process, regardless of the tag set by the source process in MPI_Send.

  • Exercise 6: Start a number of processes N divisible by 4. Divide the processes into groups of 4 and have them send their ranks in a circle (ring). Display the old rank along with the size of the old group. Display the new rank along with the size of the new group. Each process is allowed to communicate only within its group. Use MPI_Comm_split. Each process will display its rank in the new group, the group number, and the number it received.