getpagesize(2) — Linux manual page

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 multiple 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)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                 getpagesize(2)

Pages that refer to this page: fincore(1), strace(1), mmap2(2), mmap(2), mremap(2), remap_file_pages(2), syscalls(2), numa(3), posix_memalign(3)

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