man3/get_phys_pages.3

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  25 .TH GET_PHYS_PAGES 3  2019-03-06 "GNU" "Linux Programmer's Manual"
  26 .SH NAME
  27 get_phys_pages, get_avphys_pages \- get total and available physical
  28 page counts
  29 .SH SYNOPSIS
  30 .nf
  31 .B "#include <sys/sysinfo.h>"
  32 .PP
  33 .B long int get_phys_pages(void);
  34 .B long int get_avphys_pages(void);
  35 .fi
  36 .SH DESCRIPTION
  37 The function
  38 .BR get_phys_pages ()
  39 returns the total number of physical pages of memory available on the system.
  40 .PP
  41 The function
  42 .BR get_avphys_pages ()
  43 returns the number of currently available physical pages of memory on the
  44 system.
  45 .SH RETURN VALUE
  46 On success,
  47 these functions return a nonnegative value as given in DESCRIPTION.
  48 On failure, they return \-1 and set
  49 .I errno
  50 to indicate the cause of the error.
  51 .SH ERRORS
  52 .TP
  53 .B ENOSYS
  54 The system could not provide the required information
  55 (possibly because the
  56 .I /proc
  57 filesystem was not mounted).
  58 .SH CONFORMING TO
  59 These functions are GNU extensions.
  60 .SH NOTES
  61 These functions obtain the required information by scanning the
  62 .I MemTotal
  63 and
  64 .I MemFree
  65 fields of
  66 .IR /proc/meminfo .
  67 .PP
  68 The following
  69 .BR sysconf (3)
  70 calls provide a portable means of obtaining the same information as the
  71 functions described on this page.
  72 .PP
  73 .in +4n
  74 .EX
  75 total_pages = sysconf(_SC_PHYS_PAGES);    /* total pages */
  76 avl_pages = sysconf(_SC_AVPHYS_PAGES);    /* available pages */
  77 .EE
  78 .in
  79 .SH EXAMPLE
  80 The following example shows how
  81 .BR get_phys_pages ()
  82 and
  83 .BR get_avphys_pages ()
  84 can be used.
  85 .PP
  86 .EX
  87 #include <stdio.h>
  88 #include <stdlib.h>
  89 #include <sys/sysinfo.h>
  90
  91 int
  92 main(int argc, char *argv[])
  93 {
  94     printf("This system has %ld pages of physical memory and "
  95             "%ld pages of physical memory available.\en",
  96             get_phys_pages(), get_avphys_pages());
  97     exit(EXIT_SUCCESS);
  98 }
  99 .EE
 100 .SH SEE ALSO
 101 .BR sysconf (3)