GETPAGESIZE(2) Linux Programmer's Manual GETPAGESIZE(2)
getpagesize - get memory page size
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
The size of the kind of pages that mmap uses, is found using
long sz = sysconf(_SC_PAGESIZE);
(where some systems also allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE), or
int sz = getpagesize();
This call first appeared in 4.2BSD.
SVr4, 4.4BSD, SUSv2. In SUSv2 the getpagesize() call is labeled "legacy", and in POSIX
1003.1-2001 it has been dropped. HPUX does not have this call.
Whether getpagesize() is present as a Linux system call depends on the architecture. If
it is, it returns the kernel symbol PAGE_SIZE, which is architecture and machine model
dependent. Generally, one uses binaries that are architecture but not machine model
dependent, 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 libc4, libc5, glibc 2.0 fail because their getpagesize() returns a stati-
cally derived value, and does not use a system call. Things are OK in glibc 2.1.
Linux 2.5.0 2001-12-21 GETPAGESIZE(2)