get_nprocs(3)              Library Functions Manual              get_nprocs(3)

NAME
       get_nprocs, get_nprocs_conf - get number of processors

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <sys/sysinfo.h>

       int get_nprocs(void);
       int get_nprocs_conf(void);

DESCRIPTION
       The function get_nprocs_conf() returns the number of processors
       configured by the operating system.

       The function get_nprocs() returns the number of processors currently
       available in the system.  This may be less than the number returned by
       get_nprocs_conf() because processors may be offline (e.g., on
       hotpluggable systems).

RETURN VALUE
       As given in DESCRIPTION.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |get_nprocs (), get_nprocs_conf ()           | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       GNU.

NOTES
       The current implementation of these functions is rather expensive,
       since they open and parse files in the /sys filesystem each time they
       are called.

       The following sysconf(3) calls make use of the functions documented on
       this page to return the same information.

           np = sysconf(_SC_NPROCESSORS_CONF);     /* processors configured */
           np = sysconf(_SC_NPROCESSORS_ONLN);     /* processors available */

EXAMPLES
       The following example shows how get_nprocs() and get_nprocs_conf() can
       be used.

       #include <stdio.h>
       #include <stdlib.h>
       #include <sys/sysinfo.h>

       int
       main(void)
       {
           printf("This system has %d processors configured and "
                   "%d processors available.\n",
                   get_nprocs_conf(), get_nprocs());
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       nproc(1)

Linux man-pages 6.7               2023-10-31                     get_nprocs(3)