GET_NPROCS(3)

NAME
get_nprocs, get_nprocs_conf - get number of processors

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
 | Thread safety | MT-Safe

CONFORMING TO
These functions are GNU extensions.

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 */

EXAMPLE
The following example shows how get_nprocs() and get_nprocs_conf() can be used.
#include <stdlib.h>
#include <stdio.h>
#include <sys/sysinfo.h>
int
main(int argc, char *argv[])
{
    printf("This system has %d processors configured and "
            "%d processors available.\n",
            get_nprocs_conf(), get_nprocs());
    exit(EXIT_SUCCESS);
}

COLOPHON
This page is part of release 4.01 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.