procpri/t_sched_getaffinity.c

This is procpri/t_sched_getaffinity.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is a supplementary file for Chapter 35.

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

 

Download procpri/t_sched_getaffinity.c

  Cover of The Linux Programming Interface

Function list (Bold in this list means a function is not static)

/* t_sched_getaffinity.c

   Demonstrate the use of the sched_getaffinity() system call to retrieve
   the CPU affinity of a process.

   Usage: t_sched_getaffinity pid

   See also t_sched_setaffinity.c.

   This program is Linux-specific. The CPU affinity system calls are provided
   since kernel 2.6.
*/
#define _GNU_SOURCE
#include <sched.h>
#include "tlpi_hdr.h"
int
main(int argc, char *argv[])
{
    if (argc != 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s pid\n", argv[0]);

    pid_t pid = getInt(argv[1], GN_NONNEG, "pid");

    cpu_set_t set;
    int s = sched_getaffinity(pid, sizeof(cpu_set_t), &set);
    if (s == -1)
        errExit("sched_getaffinity");

    printf("CPUs:");
    for (int cpu = 0; cpu < CPU_SETSIZE; cpu++)
        if (CPU_ISSET(cpu, &set))
            printf(" %d", cpu);
    printf("\n");

    exit(EXIT_SUCCESS);
}

 

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