Scheduling

omp_sched_t

Definition

The structure omp_sched_t represents a schedule that can be passed to omp_set_schedule, or retrieved from omp_get_schedule, as well as the modifier that can be applied to that schedule. Its possible values are omp_sched_static, omp_sched_dynamic, omp_sched_auto, omp_sched_guided and omp_sched_monotonic. The first four correspond go the static, dynamic, auto and guided schedules respectively. The last one corresponds to the monotonic modifier.

Example

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

/**
 * @brief Illustrates the use of the omp_sched_t.
 * @details A for loop is parallelised across 4 threads using the runtime
 * schedule policy. The schedule to apply is defined by omp_set_schedule as 
 * being a dynamic scheduling with chunks made of 4 iterations.
 **/
int main(int argc, char* argv[])
{
    // Use 4 threads when creating OpenMP parallel regions
    omp_set_num_threads(4);

    // Tell OpenMP which scheduling policy and chunk size use for runtime schedule clauses
    omp_sched_t kind = omp_sched_dynamic;
    omp_set_schedule(kind, 2);

    // Parallelise the for loop using the runtime schedule
    #pragma omp parallel for schedule(runtime)
    for(int i = 0; i < 10; i++)
    {
        printf("Thread %d processes iteration %d.\n", omp_get_thread_num(), i);
    }

    return EXIT_SUCCESS;
}