lecture01-mpi_introduction

MPI basics

yulyugin@gmail.com

Евгений Юлюгин

Environment

Google-группа

mipt-parallel-computing

SSH-сервер

host: openmp.mipt.ru

port: 22805

username: s<group_number><student_number>

password: mpirun-np

usage: ssh username@openmp.mipt.ru –p 22805

MPI history

MPI – Massage Passing Interface.

Первая версия разрабатывалась в 1993—1994 годах.

MPI 1 вышла в 1994.

MPI 1.1 опубликован 12 июня 1991. Первая реализация 2002 год

Intel Cilk Plus

MPI_Init() & MPI_Finalize()

int MPI_Init(int *pargc, char ***pargv);

int MPI_Finalize(void);

Defined in mpi.h

Служат для инициализации и завершения MPIпроцесса

Self-identification (1/2)

MPI_Comm_size(MPI_Comm comm, int *size);

Returns the size of the group associated with communicator.

MPI_Comm_rank(MPI_Comm comm, int *rank);

Determines the rank of the calling process in the communicator

Self-identification (2/2)

MPI_Comm:

MPI_COMM_SELF,

User defined communicators,

MPI_COMM_WORLD is the initially defined universe intracommunicator for all processes to conduct various communications once MPI_INIT has been called.

Send/Receive Overview (1/3)

int MPI_Send(void *buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm);

int MPI_Recv(void *buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm, MPI_Status status);

Send/Receive Overview (2/3)

MPI_Datatype:

MPI_CHAR,

MPI_INT,

MPI_UNSIGNED,

MPI_DOUBLE,

etc.,

Custom data types.

Send/Receive Overview (3/3)

tag:

Number to identify the message,

MPI_ANY_TAG.

MPI_Status:

Contains additional information about received message.

MPI_STATUS_IGNORE – special value to save resources if you won’t examine the status field