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get_nprocs

Section: C Library Functions (3)
Updated: 202-0-08
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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	M-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.[rs]n",
            get_nprocs_conf(), get_nprocs());
    exit(EXIT_SUCCESS); }