GETPAGESIZE(2) Linux Programmer's Manual GETPAGESIZE(2)

NAME
       getpagesize - get memory page size

SYNOPSIS
       #include 

       int getpagesize(void);

   Feature Test Macro Requirements for glibc (see featuretestmacros(7)):

       getpagesize():
           Since glibc 2.12:
               BSDSOURCE ||
                   !(POSIXCSOURCE >= 200112L || XOPENSOURCE >= 600)
           Before glibc 2.12:
               BSDSOURCE || XOPENSOURCE >= 500 ||
               XOPENSOURCE && XOPENSOURCEEXTENDED

DESCRIPTION
       The function getpagesize() returns the number  of  bytes  in  a  memory
       page, where "page" is a fixed-length block, the unit for memory alloca‐
       tion and file mapping performed by mmap(2).

CONFORMING TO
       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.

NOTES
       Portable applications should employ  sysconf(SCPAGESIZE)  instead  of
       getpagesize():

           #include 
           long sz = sysconf(SCPAGESIZE);

       (Most systems allow the synonym SCPAGESIZE for SCPAGESIZE.)

       Whether  getpagesize() is present as a Linux system call depends on the
       architecture.  If it is, it returns the kernel symbol PAGESIZE,  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 archi‐
       tecture.  This means that a user program should not find  PAGESIZE  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.

SEE ALSO
       mmap(2), sysconf(3)

COLOPHON
       This  page  is  part of release 3.53 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



Linux                             2010-11-16                    GETPAGESIZE(2)