get_phys_pages(3) [centos man page]
GET_PHYS_PAGES(3) Linux Programmer's Manual GET_PHYS_PAGES(3) NAME
get_phys_pages, get_avphys_pages - get total and available physical page counts SYNOPSIS
#include <sys/sysinfo.h> long int get_phys_pages(void); long int get_avphys_pages(void); DESCRIPTION
The function get_phys_pages() returns the total number of physical pages of memory available on the system. The function get_avphys_pages() returns the number of currently available physical pages of memory on the system. RETURN VALUE
On success, these functions return a nonnegative value as given in DESCRIPTION. On failure, they return -1 and set errno to indicate the cause of the error. ERRORS
ENOSYS The system could not provide the required information (possibly because the /proc filesystem was not mounted). CONFORMING TO
These functions are GNU extensions. NOTES
These functions obtain the required information by scanning the MemTotal and MemFree fields of /proc/meminfo. The following sysconf(3) calls provide a portable means of obtaining the same information as the functions described on this page. total_pages = sysconf(_SC_PHYS_PAGES); /* total pages */ avl_pages = sysconf(_SC_AVPHYS_PAGES); /* available pages */ EXAMPLE
The following example shows how get_phys_pages() and get_avphys_pages() can be used. #include <stdio.h> #include <stdlib.h> #include <sys/sysinfo.h> int main(int argc, char *argv[]) { printf("This system has %ld pages of physical memory and " "%ld pages of physical memory available. ", get_phys_pages(), get_avphys_pages()); exit(EXIT_SUCCESS); } SEE ALSO
sysconf(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. GNU 2017-09-15 GET_PHYS_PAGES(3)
Check Out this Related Man Page
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() because 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(), | Thread safety | MT-Safe | |get_nprocs_conf() | | | +------------------+---------------+---------+ 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 */ EXAMPLE
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. ", get_nprocs_conf(), get_nprocs()); exit(EXIT_SUCCESS); } SEE ALSO
nproc(1) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. GNU
2017-09-15 GET_NPROCS(3)