Originální popis anglicky:
getpagesize - get memory page size
Návod, kniha: Linux Programmer's Manual
#include <unistd.h>
int getpagesize(void);
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 uses, is found using
#include <unistd.h>
long sz = sysconf(_SC_PAGESIZE);
(where some systems also allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE), or
#include <unistd.h>
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 statically derived value, and does not use a
system call. Things are OK in glibc 2.1.
mmap(2),
sysconf(3)
