A simple C program to test thread pinning

pintest.c

/* pintest.c
 * Runs n threads, pinned to the first n CPUs, until you press enter.
 * n is specified as a command line argument.
 * Each thread runs an infinite loop (100% cpu usage in theory).
 */

#define _GNU_SOURCE
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void *func(void *arg __attribute__((unused)))
{
    for (;;)
        ;
}

int pin_thread(pthread_t thr, int core)
{
    cpu_set_t cpuset;
    CPU_ZERO(&cpuset);
    CPU_SET(core, &cpuset);

    return pthread_setaffinity_np(thr, sizeof(cpu_set_t), &cpuset);
}

int main(int argc, char **argv)
{
    int n_threads, n_cores_total;
    pthread_t *thread_ids;

    if (argc != 2)
    {
        printf("Usage: %s [n threads]\n", argv[0]);
        return EXIT_FAILURE;
    }

    n_threads = atoi(argv[1]);
    n_cores_total = sysconf(_SC_NPROCESSORS_ONLN);

    printf("n_threads = %d\nn_cpus = %d\n", n_threads, n_cores_total);

    if (n_threads > n_cores_total)
    {
        printf("n_threads > n_cores, quitting...\n");
        return EXIT_FAILURE;
    }
    else if (n_threads <= 0)
    {
        printf("n_threads < 1, quitting...\n");
        return EXIT_FAILURE;
    }

    thread_ids = malloc(sizeof(pthread_t) * n_threads);

    if (!thread_ids)
    {
        printf("Couldn't allocate memory for thread array.");
        return EXIT_FAILURE;
    }

    for (int i = 0; i < n_threads; i++)
    {
        if (pthread_create(&thread_ids[i], NULL, func, NULL) != 0)
        {
            printf("Failed to create thread %d.\n", i);
            goto error;
        }

        if (pin_thread(thread_ids[i], i) != 0)
        {
            printf("Failed to pin thread %d.\n", i);
            goto error;
        }
    }

    printf("Threads are running. Press ENTER to stop.\n");
    getchar();

    for (int i = 0; i < n_threads; i++)
    {
        if (pthread_cancel(thread_ids[i]) != 0)
        {
            printf("Failed to cancel thread %d. Skipping...\n", i);
        }
    }

    free(thread_ids);
    return EXIT_SUCCESS;

error:
    free(thread_ids);
    return EXIT_FAILURE;
}