get_nprocs, get_nprocs_conf — 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).

Interface Attribute Value
Thread safety MT-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 5.04 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).

2019-03-06 GNU Linux Programmer's Manual