get_nprocs(3)

1get_nprocs(3)              Library Functions Manual              get_nprocs(3)
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NAME

6       get_nprocs, get_nprocs_conf - get number of processors
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

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

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

27       As given in DESCRIPTION.
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ATTRIBUTES

30       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
31       tributes(7).
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33       ┌────────────────────────────────────────────┬───────────────┬─────────┐
34       │Interface                                   │ Attribute     │ Value   │
35       ├────────────────────────────────────────────┼───────────────┼─────────┤
36       │get_nprocs(), get_nprocs_conf()             │ Thread safety │ MT-Safe │
37       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

40       GNU.
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NOTES

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

54       The  following example shows how get_nprocs() and get_nprocs_conf() can
55       be used.
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57       #include <stdio.h>
58       #include <stdlib.h>
59       #include <sys/sysinfo.h>
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61       int
62       main(void)
63       {
64           printf("This system has %d processors configured and "
65                   "%d processors available.\n",
66                   get_nprocs_conf(), get_nprocs());
67           exit(EXIT_SUCCESS);
68       }
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