Registers the arrival of a processing element (PE) at a barrier and suspends PE execution until all other PEs arrive at the barrier.
#include <shmem.h> void shmem_barrier_all(void);
Barriers are a fast way to synchronize all PEs
shmem_barrier_all function registers the arrival of the calling PE at a barrier. It also causes the PE to suspend execution until all PEs have arrived shmem_barrier_all.
Before returning from shmem_barrier_all, all previously issued local memory stores and remote memory updates issued via IBM openshmem calls such as shmem_put, are ensured finished.
Please refer to Atomicity and Coherency section for atomicity and coherence model in the OpenSHMEM documentation
#include <stdlib.h>
#include <stdio.h>
#include <shmem.h>
#define GLOBAL_ARRAY_SIZE 20
#define SOURCE_STRIDE 3
#define TARGET_STRIDE 4
#define NUM_OF_TRANS_ELEM 5
static int gIntArray[GLOBAL_ARRAY_SIZE] = {0};
int main (int argc, char* argv[])
{
int total_tasks = -1;
int my_task = -1;
start_pes(0);
total_tasks = _num_pes();
if (total_tasks <= 0) {
printf("FAILED\n");
exit(1);
} else {
printf("number of pes is %d\n", total_tasks);
}
if (total_tasks < 2 || total_tasks % 2) {
printf("FAILED: The number of pes should be an even number. (at least 2)\n");
exit(1);
}
my_task = _my_pe();
if (my_task < 0){
printf("FAILED\n");
exit(1);
} else {
printf("my pe id is %d\n", my_task);
}
printf("The address of gIntArray is %p\n", gIntArray);
// even tasks put value to odd tasks
if (my_task%2 == 0) {
int tgt_task = my_task + 1;
printf("The Source Stride is: %d, the following data will be put.\n", SOURCE_STRIDE);
}
shmem_int_iput(gIntArray, gIntArray, TARGET_STRIDE, SOURCE_STRIDE, NUM_OF_TRANS_ELEM, tgt_task);
}
shmem_barrier_all();
Subroutines: shmem_barrier, shmem_init