3.2 Process Creation

void SMP_Init(void);

SUBROUTINE SMP_INIT

• initializes SMPlib parameters, should be the first thing (other than those setting options such as SMP_Setoption) to call in an SMP program. Environment variable SMP_TMPDIR is used to define the directory for temporary SMPlib files, default to ``." (the current working directory). Environment variable SMP_DEBUG is checked.

int SMP_Fork(int num_procs);

INTEGER FUNCTION SMP_FORK(NUM_PROCS)
INTEGER NUM_PROCS

• forks ``num_procs" processes and return the rank (0 to num_procs-1) of the current process in the process group. If num_procs=0, the environment variable SMP_NUM_PROCS will be used. If SMP_NUM_PROCS is undefined, no subprocess is created, i.e. num_procs=1 is used. Number of threads per process is defined by the environment variable OMP_NUM_THREADS. If OMP_NUM_THREADS is undefined, one (1) is assumed.
• error code: SMP_ERR_NPROC, SMP_ERR_NTHR

int SMP_Forkthread(int num_procs, int num_threads[]);

INTEGER FUNCTION SMP_FORKTHREAD(NUM_PROCS, NUM_THREADS)
INTEGER NUM_PROCS, NUM_THREADS(0:*)

• forks ``num_procs" processes and return the rank (0 to num_procs-1) of the current process in the process group. If num_procs=0, the environment variable SMP_NUM_PROCS will be used. If SMP_NUM_PROCS is undefined, no subprocess is created, i.e. num_procs=1 is used. In addition, num_threads[i] of threads is specified for process i. If num_threads[i] is 0, the variable OMP_NUM_THREADS will be checked; if OMP_NUM_THREADS is undefined, one (1) is assumed.
• error code: SMP_ERR_NPROC, SMP_ERR_NTHR

void SMP_Finish(void);

SUBROUTINE SMP_FINISH

• finishes and cleans up things, should be called by all processes. Any previously allocated shared memory buffers will be freed at this point. All subprocesses perform a join function and only the master process may continue execution after SMP_Finish(). Use of this function is important for cases where only the master process is allowed for further execution, such as, when mixing SMP with MPI.

void SMP_Join(void);

SUBROUTINE SMP_JOIN

• joins all the forked processes, should be called by all processes. This function is very similar to SMP_Finish() except that it does not free any previously allocated shared memory buffers. Only the master process may continue execution after SMP_Join().