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GET_NPROCS(3)                                                           Linux Programmer's Manual                                                          GET_NPROCS(3)

NAME
       get_nprocs, get_nprocs_conf - get number of processors

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() be‐
       cause 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 │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       These functions are GNU extensions.

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 <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);
       }

SEE ALSO
       nproc(1)

GNU                                                                            2021-03-22                                                                  GET_NPROCS(3)