get_nprocs_conf - Man Page

get number of processors


#include <sys/sysinfo.h>

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


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.


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

get_nprocs(), get_nprocs_conf()Thread safetyMT-Safe

Conforming to

These functions are GNU extensions.


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 */


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

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

main(int argc, char *argv[])
    printf("This system has %d processors configured and "
            "%d processors available.\n",
            get_nprocs_conf(), get_nprocs());

See Also



This page is part of release 5.13 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

Referenced By

sched_setaffinity(2), sysconf(3).

The man page get_nprocs(3) is an alias of get_nprocs_conf(3).

2021-03-22 GNU Linux Programmer's Manual