getpagesize(3c) [v7 man page]

getpagesize(3C) 					   Standard C Library Functions 					   getpagesize(3C)

NAME

       getpagesize - get system page size

SYNOPSIS

       #include <unistd.h>

       int getpagesize(void);

DESCRIPTION

       The  getpagesize()  function  returns  the  number of bytes in a page. Page granularity is the granularity of many of the memory management
       calls.

       The page size is a system page size and need not be the same as the underlying hardware page size.

       The getpagesize() function is equivalent to sysconf(_SC_PAGE_SIZE) and sysconf(_SC_PAGESIZE). See sysconf(3C).

RETURN VALUES

       The getpagesize() function returns the current page size.

ERRORS

       No errors are defined.

USAGE

       The value returned by getpagesize() need not be the minimum value that malloc(3C) can allocate.	Moreover, the  application  cannot  assume
       that an object of this size can be allocated with malloc().

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       pagesize(1), brk(2), getrlimit(2), mmap(2), mprotect(2), munmap(2), malloc(3C), msync(3C), sysconf(3C), attributes(5)

SunOS 5.10							    27 Jun 2000 						   getpagesize(3C)

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

NAME

       getpagesize - get memory page size

SYNOPSIS

       #include <unistd.h>

       int getpagesize(void);

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

       getpagesize(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

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(2) uses, is found using

	   #include <unistd.h>
	   long sz = sysconf(_SC_PAGESIZE);

       (most systems allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE), or

	   #include <unistd.h>
	   int sz = getpagesize();

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.  Portable applications should employ sysconf(_SC_PAGESIZE) instead of 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,
       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 depen-
       dency  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 3.25 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								    2007-07-26							    GETPAGESIZE(2)