GETPAGESIZE(2) Linux Programmer's Manual GETPAGESIZE(2)
NAME
getpagesize - get memory page size
SYNOPSIS
#include<unistd.h>
intgetpagesize(void);
DESCRIPTION
The function getpagesize() returns the number of bytes in a page, where
a "page" is the thing used where it says in the description of mmap(2)
that files are mapped in page-sized units.
The size of the kind of pages that mmap uses, is found using
#include <unistd.h>
long sz = sysconf(_SC_PAGESIZE);
(where some systems also allow the synonym _SC_PAGE_SIZE for _SC_PAGE-
SIZE), or
#include <unistd.h>
int sz = getpagesize();
HISTORY
This call first appeared in 4.2BSD.
CONFORMINGTO
SVr4, 4.4BSD, SUSv2. In SUSv2 the getpagesize() call is labeled
"legacy", and in POSIX 1003.1-2001 it has been dropped. HPUX does not
have this call.
NOTES
Whether getpagesize() is present as a Linux system call depends on the
architecture. If it is, it returns the kernel symbol PAGE_SIZE, which
is architecture and machine model dependent. Generally, one uses bina-
ries that are architecture but not machine model dependent, in order to
have a single binary distribution per architecture. This means that a
user program should not find PAGE_SIZE at compile time from a header
file, but use an actual system call, at least for those architectures
(like sun4) where this dependency exists. Here libc4, libc5, glibc 2.0
fail because their getpagesize() returns a statically derived value,
and does not use a system call. Things are OK in glibc 2.1.
SEEALSO
mmap(2), sysconf(3)
Linux 2.5.0 2001-12-21 GETPAGESIZE(2)
Take our 
