get_nprocs_conf(3) Linux Man Page

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). allbox; lbx lb lb T{ get_nprocs()get_nprocs_conf()

Interface	Attribute	Value
T}	Thread safety	MT-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.\en",
            get_nprocs_conf(), get_nprocs());
    exit(EXIT_SUCCESS);
}

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