|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLE | COLOPHON |
GET_NPROCS(3) Linux Programmer's Manual GET_NPROCS(3)
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).
As given in DESCRIPTION.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────┼───────────────┼─────────┤
│get_nprocs(), │ Thread safety │ MT-Safe │
│get_nprocs_conf() │ │ │
└──────────────────┴───────────────┴─────────┘
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>
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);
}
This page is part of release 4.12 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
https://www.kernel.org/doc/man-pages/.
GNU 2015-04-19 GET_NPROCS(3)
Pages that refer to this page: sched_setaffinity(2)