getpagesize(2) System Calls Manual getpagesize(2)
NAME
getpagesize - get memory page size
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <unistd.h>
int getpagesize(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getpagesize():
Since glibc 2.20:
_DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
glibc 2.12 to glibc 2.19:
_BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
DESCRIPTION
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).
VERSIONS
A user program should not hard-code a page size, neither as a literal
nor using the PAGE_SIZE macro, because some architectures support multi-
ple page sizes.
This manual page is in section 2 because Alpha, SPARC, and SPARC64 all
have a Linux system call getpagesize() though other architectures do
not, and use the ELF auxiliary vector instead.
STANDARDS
None.
HISTORY
This call first appeared in 4.2BSD. SVr4, 4.4BSD, SUSv2. In SUSv2 the
getpagesize() call was labeled LEGACY, and it was removed in
POSIX.1-2001.
glibc 2.0 returned a constant even on architectures with multiple page
sizes.
SEE ALSO
mmap(2), sysconf(3)
Linux man-pages 6.9.1 2024-05-02 getpagesize(2)
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