get_nprocs(3) - Linux manual page (original) (raw)

getnprocs(3) Library Functions Manual getnprocs(3)

NAME top

   get_nprocs, get_nprocs_conf - get number of processors

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <sys/sysinfo.h>**

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

DESCRIPTION top

   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 top

   As given in DESCRIPTION.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **get_nprocs**(), **get_nprocs_conf**()      │ Thread safety │ MT-Safe │
   └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

   GNU.

NOTES top

   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)](../man3/sysconf.3.html) 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 top

   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.\n",
               get_nprocs_conf(), get_nprocs());
       exit(EXIT_SUCCESS);
   }

SEE ALSO top

   [nproc(1)](../man1/nproc.1.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 getnprocs(3)

Pages that refer to this page:sched_setaffinity(2), sysconf(3)