get_nprocs (3)

Leading comments

Copyright (c) 2012, Petr Benas
and Copyright (c) 2012, Michael Kerrisk <mtk.man-pages@gmail.com>

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(The comments found at the beginning of the groff file "man3/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
get_nprocs(), get_nprocs_conf()	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

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