mirror of https://github.com/mkerrisk/man-pages
106 lines
3.0 KiB
Groff
106 lines
3.0 KiB
Groff
.\" Copyright (c) 2015 William Woodruff (william@tuffbizz.com)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH GET_PHYS_PAGES 3 2021-03-22 "GNU" "Linux Programmer's Manual"
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.SH NAME
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get_phys_pages, get_avphys_pages \- get total and available physical
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page counts
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.SH SYNOPSIS
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.nf
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.B "#include <sys/sysinfo.h>"
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.PP
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.B long get_phys_pages(void);
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.B long get_avphys_pages(void);
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.fi
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.SH DESCRIPTION
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The function
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.BR get_phys_pages ()
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returns the total number of physical pages of memory available on the system.
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.PP
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The function
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.BR get_avphys_pages ()
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returns the number of currently available physical pages of memory on the
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system.
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.SH RETURN VALUE
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On success,
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these functions return a nonnegative value as given in DESCRIPTION.
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On failure, they return \-1 and set
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.I errno
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to indicate the error.
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.SH ERRORS
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.TP
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.B ENOSYS
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The system could not provide the required information
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(possibly because the
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.I /proc
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filesystem was not mounted).
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.SH CONFORMING TO
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These functions are GNU extensions.
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.SH NOTES
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Before glibc 2.23,
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these functions obtained the required information by scanning the
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.I MemTotal
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and
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.I MemFree
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fields of
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.IR /proc/meminfo .
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Since glibc 2.23,
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these functions obtain the required information by calling
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.BR sysinfo (2).
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.PP
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The following
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.BR sysconf (3)
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calls provide a portable means of obtaining the same information as the
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functions described on this page.
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.PP
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.in +4n
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.EX
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total_pages = sysconf(_SC_PHYS_PAGES); /* total pages */
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avl_pages = sysconf(_SC_AVPHYS_PAGES); /* available pages */
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.EE
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.in
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.SH EXAMPLES
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The following example shows how
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.BR get_phys_pages ()
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and
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.BR get_avphys_pages ()
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can be used.
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.PP
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.EX
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/sysinfo.h>
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int
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main(int argc, char *argv[])
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{
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printf("This system has %ld pages of physical memory and "
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"%ld pages of physical memory available.\en",
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get_phys_pages(), get_avphys_pages());
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exit(EXIT_SUCCESS);
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}
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.EE
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.SH SEE ALSO
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.BR sysconf (3)
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