shmem_float_put

Purpose

Transfers data to a specified processing element(PE).

C syntax

#include <shmem.h>
 
void shmem_float_put(float *target, const float *source, size_t len, int pe);
 

Parameters

INPUT
target
Data object to be updated on the remote PE. This data object must be remotely accessible.
source
Data object containing the data to be copied.
len
Number of elements in the target and source arrays.
pe
Processing element number of the remote PE.

Description

This routine provides a high-performance method for copying a contiguous data object from the local PE to a contiguous data object on a different PE

This routine returns when the data has been copied out of the source array on the local PE, but not necessarily before the data has been delivered to the remote data object. To enforce the ordering/completion of the put routines, the use of shmem_fence, shmem_quiet, shmem_barrier or shmem_barrier_all is needed.

The function shmem_float_put() writes contiguous elements of float type to the remote PE.

IBM NOTES

Please refer to Atomicity and Coherency section for atomicity and coherence model in the OpenSHMEM documentation

C examples

#include <stdlib.h>
#include <stdio.h>

#include <shmem.h>

#define GLOBAL_ARRAY_SIZE 10
#define INT_INIT_VALUE 1234
//can not use #define
const float FLOAT_INIT_VALUE = 1234.123456;

static float gFloatElement = 0;
static float gFloatArray[GLOBAL_ARRAY_SIZE] = {0};

static int gIntElement = 0;
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 gIntElement is %p\n", &gIntElement);
    printf("The address of gIntArray is %p\n", gIntArray);

    printf("The address of gFloatElement is %p\n", &gFloatElement);
    printf("The address of gFloatArray is %p\n", gFloatArray);

    // even tasks put value to odd tasks
    if (my_task%2 == 0) {
        int tgt_task = my_task + 1;
   
        //for int
        gIntElement = INT_INIT_VALUE;
        for (int i=0; i<GLOBAL_ARRAY_SIZE; i++) {
            gIntArray[i] = INT_INIT_VALUE;
        }
        
        shmem_int_p(&gIntElement, gIntElement, tgt_task);
        shmem_int_put(gIntArray, gIntArray, GLOBAL_ARRAY_SIZE, tgt_task);

        //for float
        gFloatElement = FLOAT_INIT_VALUE;
        for (int i=0; i<GLOBAL_ARRAY_SIZE; i++) {
            gFloatArray[i] = FLOAT_INIT_VALUE;
        }
        
        shmem_float_p(&gFloatElement, gFloatElement, tgt_task);
        shmem_float_put(gFloatArray, gFloatArray, GLOBAL_ARRAY_SIZE, tgt_task);
    }

    shmem_barrier_all();

    // odd tasks check value
    if (my_task%2 == 1) {
        //for int
        if (gIntElement != INT_INIT_VALUE) {
            printf("FAILED: element should be %d instead of %d\n", INT_INIT_VALUE, gIntElement);
            exit(1);
        }

        for (int i=0; i<GLOBAL_ARRAY_SIZE; i++) {
            if (gIntArray[i] != INT_INIT_VALUE) {
                printf("FAILED, array[%d] should be %d instead of %d\n", i, INT_INIT_VALUE, gIntArray[i]);
            }
        }
        
        //for float
        if (gFloatElement != FLOAT_INIT_VALUE) {
            printf("FAILED: element should be %f instead of %f\n", FLOAT_INIT_VALUE, gFloatElement);
            exit(1);
        }

        for (int i=0; i<GLOBAL_ARRAY_SIZE; i++) {
            if (gFloatArray[i] != FLOAT_INIT_VALUE) {
                printf("FAILED, array[%d] should be %f instead of %f\n", i, FLOAT_INIT_VALUE, gFloatArray[i]);
            }
        }
    }

    shmem_barrier_all();

    printf("PASSED\n");
    return 0;
}

Related information

Subroutines: shmem_barrier, shmem_put, shmem_fence, shmem_iput, shmem_quiet


OpenSHMEM API Index