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| .TH GET_NPROCS 3 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| get_nprocs, get_nprocs_conf \- get number of processors |
| .SH SYNOPSIS |
| .nf |
| .B #include <sys/sysinfo.h> |
| .PP |
| .BI "int get_nprocs(void);" |
| .BI "int get_nprocs_conf(void);" |
| .fi |
| .SH DESCRIPTION |
| The function |
| .BR get_nprocs_conf () |
| returns the number of processors configured by the operating system. |
| .PP |
| The function |
| .BR get_nprocs () |
| returns the number of processors currently available in the system. |
| This may be less than the number returned by |
| .BR get_nprocs_conf () |
| because processors may be offline (e.g., on hotpluggable systems). |
| .SH RETURN VALUE |
| As given in DESCRIPTION. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR get_nprocs (), |
| .BR get_nprocs_conf () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| These functions are GNU extensions. |
| .SH NOTES |
| The current |
| .\" glibc 2.15 |
| implementation of these functions is rather expensive, |
| since they open and parse files in the |
| .I /sys |
| filesystem each time they are called. |
| .PP |
| The following |
| .BR sysconf (3) |
| calls make use of the functions documented on this page |
| to return the same information. |
| .PP |
| .in +4n |
| .EX |
| np = sysconf(_SC_NPROCESSORS_CONF); /* processors configured */ |
| np = sysconf(_SC_NPROCESSORS_ONLN); /* processors available */ |
| .EE |
| .in |
| .SH EXAMPLES |
| The following example shows how |
| .BR get_nprocs () |
| and |
| .BR get_nprocs_conf () |
| can be used. |
| .PP |
| .EX |
| #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.\en", |
| get_nprocs_conf(), get_nprocs()); |
| exit(EXIT_SUCCESS); |
| } |
| .EE |
| .SH SEE ALSO |
| .BR nproc (1) |