projects / thirdparty / man-pages.git / blame
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| a1eaacb1 | 1 | '\" t |
| 5ba917a9 AC |
2 | .\" Copyright (c) 2012, Petr Benas |
| 3 | .\" and Copyright (c) 2012, Michael Kerrisk <mtk.man-pages@gmail.com> | |
| 4 | .\" | |
| 5 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft | |
| 6 | .\" | |
| 7 | .TH get_nprocs 3 (date) "Linux man-pages (unreleased)" | |
| 8 | .SH NAME | |
| 9 | get_nprocs, get_nprocs_conf \- get number of processors | |
| 10 | .SH LIBRARY | |
| 11 | Standard C library | |
| 12 | .RI ( libc ", " \-lc ) | |
| 13 | .SH SYNOPSIS | |
| 14 | .nf | |
| 15 | .B #include <sys/sysinfo.h> | |
| 16 | .PP | |
| 17 | .B int get_nprocs(void); | |
| 18 | .B int get_nprocs_conf(void); | |
| 19 | .fi | |
| 20 | .SH DESCRIPTION | |
| 21 | The function | |
| 22 | .BR get_nprocs_conf () | |
| 23 | returns the number of processors configured by the operating system. | |
| 24 | .PP | |
| 25 | The function | |
| 26 | .BR get_nprocs () | |
| 27 | returns the number of processors currently available in the system. | |
| 28 | This may be less than the number returned by | |
| 29 | .BR get_nprocs_conf () | |
| 30 | because processors may be offline (e.g., on hotpluggable systems). | |
| 31 | .SH RETURN VALUE | |
| 32 | As given in DESCRIPTION. | |
| 33 | .SH ATTRIBUTES | |
| 34 | For an explanation of the terms used in this section, see | |
| 35 | .BR attributes (7). | |
| 36 | .ad l | |
| 37 | .nh | |
| 38 | .TS | |
| 39 | allbox; | |
| 40 | lbx lb lb | |
| 41 | l l l. | |
| 42 | Interface Attribute Value | |
| 43 | T{ | |
| 44 | .BR get_nprocs (), | |
| 45 | .BR get_nprocs_conf () | |
| 46 | T} Thread safety MT-Safe | |
| 47 | .TE | |
| 48 | .hy | |
| 49 | .ad | |
| 50 | .sp 1 | |
| 51 | .SH STANDARDS | |
| 52 | These functions are GNU extensions. | |
| 53 | .SH NOTES | |
| 54 | The current | |
| 55 | .\" glibc 2.15 | |
| 56 | implementation of these functions is rather expensive, | |
| 57 | since they open and parse files in the | |
| 58 | .I /sys | |
| 59 | filesystem each time they are called. | |
| 60 | .PP | |
| 61 | The following | |
| 62 | .BR sysconf (3) | |
| 63 | calls make use of the functions documented on this page | |
| 64 | to return the same information. | |
| 65 | .PP | |
| 66 | .in +4n | |
| 67 | .EX | |
| 68 | np = sysconf(_SC_NPROCESSORS_CONF); /* processors configured */ | |
| 69 | np = sysconf(_SC_NPROCESSORS_ONLN); /* processors available */ | |
| 70 | .EE | |
| 71 | .in | |
| 72 | .SH EXAMPLES | |
| 73 | The following example shows how | |
| 74 | .BR get_nprocs () | |
| 75 | and | |
| 76 | .BR get_nprocs_conf () | |
| 77 | can be used. | |
| 78 | .PP | |
| 79 | .\" SRC BEGIN (get_nprocs_conf.c) | |
| 80 | .EX | |
| 81 | #include <stdio.h> | |
| 82 | #include <stdlib.h> | |
| 83 | #include <sys/sysinfo.h> | |
| 84 | ||
| 85 | int | |
| 86 | main(void) | |
| 87 | { | |
| 88 | printf("This system has %d processors configured and " | |
| 89 | "%d processors available.\en", | |
| 90 | get_nprocs_conf(), get_nprocs()); | |
| 91 | exit(EXIT_SUCCESS); | |
| 92 | } | |
| 93 | .EE | |
| 94 | .\" SRC END | |
| 95 | .SH SEE ALSO | |
| 96 | .BR nproc (1) |