get_nprocs(3)

1GET_NPROCS(3)              Linux Programmer's Manual             GET_NPROCS(3)
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NAME

6       get_nprocs, get_nprocs_conf - get number of processors
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SYNOPSIS

9       #include <sys/sysinfo.h>
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11       int get_nprocs(void);
12       int get_nprocs_conf(void);
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DESCRIPTION

15       The function get_nprocs_conf() returns the number of processors config‐
16       ured by the operating system.
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18       The function get_nprocs() returns the number  of  processors  currently
19       available  in the system.  This may be less than the number returned by
20       get_nprocs_conf() because processors may be offline (e.g., on  hotplug‐
21       gable systems).
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RETURN VALUE

24       As given in DESCRIPTION.
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ATTRIBUTES

27       For   an   explanation   of   the  terms  used  in  this  section,  see
28       attributes(7).
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30       ┌──────────────────┬───────────────┬─────────┐
31       │Interface         │ Attribute     │ Value   │
32       ├──────────────────┼───────────────┼─────────┤
33       │get_nprocs(),     │ Thread safety │ MT-Safe │
34       │get_nprocs_conf() │               │         │
35       └──────────────────┴───────────────┴─────────┘
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CONFORMING TO

38       These functions are GNU extensions.
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NOTES

41       The current implementation of  these  functions  is  rather  expensive,
42       since  they  open and parse files in the /sys filesystem each time they
43       are called.
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45       The following sysconf(3) calls make use of the functions documented  on
46       this page to return the same information.
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48           np = sysconf(_SC_NPROCESSORS_CONF);     /* processors configured */
49           np = sysconf(_SC_NPROCESSORS_ONLN);     /* processors available */
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EXAMPLE

52       The  following example shows how get_nprocs() and get_nprocs_conf() can
53       be used.
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55       #include <stdlib.h>
56       #include <stdio.h>
57       #include <sys/sysinfo.h>
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59       int
60       main(int argc, char *argv[])
61       {
62           printf("This system has %d processors configured and "
63                   "%d processors available.\n",
64                   get_nprocs_conf(), get_nprocs());
65           exit(EXIT_SUCCESS);
66       }
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COLOPHON

72       This page is part of release 4.15 of the Linux  man-pages  project.   A
73       description  of  the project, information about reporting bugs, and the
74       latest    version    of    this    page,    can     be     found     at
75       https://www.kernel.org/doc/man-pages/.
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79GNU                               2017-09-15                     GET_NPROCS(3)