получить размер страницы памяти (get memory page size)
Имя (Name)
getpagesize - get memory page size
Синопсис (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 2.19:
_BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
Описание (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).
Стандарты (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.
Примечание (Note)
Portable applications should employ sysconf(_SC_PAGESIZE) instead
of getpagesize():
#include <unistd.h>
long sz = sysconf(_SC_PAGESIZE);
(Most systems allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE.)
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 dependency exists. Here
glibc 2.0 fails because its getpagesize() returns a statically
derived value, and does not use a system call. Things are OK in
glibc 2.1.
Смотри также (See also)
mmap(2), sysconf(3)
