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Quiz Questions ITCS 4145/5145 Parallel Programming MPI

Quiz Questions ITCS 4145/5145 Parallel Programming MPI. What is the name of the default MPI communicator?. DEF_MPI_COMM_WORLD It has no name. DEFAULT_COMMUNICATOR COMM_WORLD MPI_COMM_WORLD. What does the MPI routine MPI_Comm_rank() do?.

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Quiz Questions ITCS 4145/5145 Parallel Programming MPI

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  1. Quiz QuestionsITCS 4145/5145Parallel ProgrammingMPI ITCS 4/5145 Parallel Programming, UNC-Charlotte, B. Wilkinson, 2013, QuizQuestions2a.ppt Jan 21, 2013

  2. What is the name of the default MPI communicator? • DEF_MPI_COMM_WORLD • It has no name. • DEFAULT_COMMUNICATOR • COMM_WORLD • MPI_COMM_WORLD

  3. What does the MPI routine MPI_Comm_rank() do? • It compares the supplied process ID with that of the process and returns TRUE or FALSE. • It returns an integer that is number of processes in the specifed communicator. The number is returned as an agument. • It converts the Linux process ID to a unique integer from zero onwards. • It returns an integer that is the rank of the process in the specifed communicator. The integer is returned as an agument. • It returns the priority number of the process from highest (0) downwards.

  4. Name one MPI routine that does not have a named communicator as a parameter (argument). • MPI_Send() • MPI_Bcast() • MPI_Init() • MPI_Barrier() • None - they all have a named communicator as a parameter. • none of the other answers

  5. What is the purpose of a message tag in MPI? • To provide a mechanism to differentiate between message-passing routines written by different programmers • To count the number of characters in a message • To indicate the type of message • To provide a matching mechanism differentiating between message sent from one process to another process

  6. When does the MPI routine MPI_Recv() return? • After the arrival of the message the routine is waiting for but before the data has been collected. • Never • Immediately • After a time specified in the routine. • After the arrival of message the routine is waiting for and the data collected.

  7. What is meant by a blocking message passing routine in MPI? • The routine returns when all the local actions are complete but the message transfer may not have completed. • The routine returns immediately but the message transfer may not have completed. • The routine returns when the message transfer has completed. • The routine blocks all actions on other processes until it has completed its actions. • None of the other answers.

  8. What is meant by a non-blocking (or asynchronous) message passing routine in MPI? • The routine returns when all the local actions are complete but the message transfer may not have completed. • The routine returns immediately but the message transfer may not have completed. • The routine returns when the message transfer has completed. • The routine blocks all actions on other processes until it has completed its actions. • None of the other answers.

  9. In the routine:MPI_Send(message,13,MPICHAR,x,10, MPI_COMM_WORLD);when can x be altered without affecting the message being transferred? • Never. • After the routine returns, i.e. in subsequent statements • Anytime • When the message has been received • None of the other answers

  10. What does the routineMPI_Wtime()do? • Waits a specific time before returning as given by an argument. • Returns the elapsed time from some point in the past, in seconds. • Returns the elapsed time from the beginning of the program execution, in seconds. • Returns the time of the process execution. • Returned the actual time of day • None of the other answers.

  11. Under what circumstance might an MPI_Send() operate as an MPI_Ssend()? • If the available message buffer space becomes exhausted. • If you specify more than a thousand bytes in the message. • If the tags do not match. • When the "synch" parameter is set in the parameter list of MPI_Send() • Never

  12. What does the MPI routine MPI_Barrier() do? • Waits for all messages to be sent and received. • Will cause processes to wait for all processes within the specific communicator to call the routine. Then all processes send a message to the master process and continue. • Makes a process to execute slower to allow debugging • Waits for a specified amount of time. • Will cause processes after calling MPI_Barrier() to wait for all processes within the specific communicator to call the routine. Then all processes are released and are allowed to continue.

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