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NAME | SYNOPSIS | DESCRIPTION | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
GETPAGESIZE(2) Linux Programmer's Manual GETPAGESIZE(2)
getpagesize - get memory page size
#include <unistd.h>
int getpagesize(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getpagesize():
Since glibc 2.19:
_DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
From glibc 2.12 to 2.19:
_BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
The function getpagesize() returns the number of bytes in a memory
page, where "page" is a fixed-length block, the unit for memory
allocation and file mapping performed by mmap(2).
SVr4, 4.4BSD, SUSv2. In SUSv2 the getpagesize() call is labeled
LEGACY, and in POSIX.1-2001 it has been dropped; HP-UX does not have
this call.
Portable applications should employ sysconf(_SC_PAGESIZE) instead of
getpagesize():
#include <unistd.h>
long sz = sysconf(_SC_PAGESIZE);
(Most systems allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE.)
Whether getpagesize() is present as a Linux system call depends on
the architecture. If it is, it returns the kernel symbol PAGE_SIZE,
whose value depends on the architecture and machine model.
Generally, one uses binaries that are dependent on the architecture
but not on the machine model, 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 glibc 2.0 fails because its
getpagesize() returns a statically derived value, and does not use a
system call. Things are OK in glibc 2.1.
mmap(2), sysconf(3)
This page is part of release 4.12 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/.
Linux 2016-03-15 GETPAGESIZE(2)
Pages that refer to this page: fincore(1), mmap2(2), mmap(2), mremap(2), remap_file_pages(2), syscalls(2), numa(3), posix_memalign(3)