MSYNC(2) Linux Programmer's Manual MSYNC(2)NAME
msync - synchronize a file with a memory map
SYNOPSIS
#include <unistd.h>
#include <sys/mman.h>
#ifdef _POSIX_MAPPED_FILES
#ifdef _POSIX_SYNCHRONIZED_IO
int msync(const void *start, size_t length, int flags);
#endif
#endif
DESCRIPTION
msync flushes changes made to the in-core copy of a file that was mapped into memory using mmap(2) back to disk. Without use of this call
there is no guarantee that changes are written back before munmap(2) is called. To be more precise, the part of the file that corresponds
to the memory area starting at start and having length length is updated. The flags argument may have the bits MS_ASYNC, MS_SYNC and
MS_INVALIDATE set, but not both MS_ASYNC and MS_SYNC. MS_ASYNC specifies that an update be scheduled, but the call returns immediately.
MS_SYNC asks for an update and waits for it to complete. MS_INVALIDATE asks to invalidate other mappings of the same file (so that they
can be updated with the fresh values just written).
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EINVAL start is not a multiple of PAGESIZE, or any bit other than MS_ASYNC | MS_INVALIDATE | MS_SYNC is set in flags.
EFAULT The indicated memory (or part of it) was not mapped.
CONFORMING TO
POSIX.1b (formerly POSIX.4)
SEE ALSO mmap(2), B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128-129 and 389-391.
Linux 1.3.86 1996-04-12 MSYNC(2)
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MSYNC(2) Linux Programmer's Manual MSYNC(2)NAME
msync - synchronize a file with a memory map
SYNOPSIS
#include <sys/mman.h>
int msync(void *addr, size_t length, int flags);
DESCRIPTION
msync() flushes changes made to the in-core copy of a file that was mapped into memory using mmap(2) back to disk. Without use of this
call there is no guarantee that changes are written back before munmap(2) is called. To be more precise, the part of the file that corre-
sponds to the memory area starting at addr and having length length is updated.
The flags argument may have the bits MS_ASYNC, MS_SYNC, and MS_INVALIDATE set, but not both MS_ASYNC and MS_SYNC. MS_ASYNC specifies that
an update be scheduled, but the call returns immediately. MS_SYNC asks for an update and waits for it to complete. MS_INVALIDATE asks to
invalidate other mappings of the same file (so that they can be updated with the fresh values just written).
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EBUSY MS_INVALIDATE was specified in flags, and a memory lock exists for the specified address range.
EINVAL addr is not a multiple of PAGESIZE; or any bit other than MS_ASYNC | MS_INVALIDATE | MS_SYNC is set in flags; or both MS_SYNC and
MS_ASYNC are set in flags.
ENOMEM The indicated memory (or part of it) was not mapped.
CONFORMING TO
POSIX.1-2001.
This call was introduced in Linux 1.3.21, and then used EFAULT instead of ENOMEM. In Linux 2.4.19 this was changed to the POSIX value
ENOMEM.
AVAILABILITY
On POSIX systems on which msync() is available, both _POSIX_MAPPED_FILES and _POSIX_SYNCHRONIZED_IO are defined in <unistd.h> to a value
greater than 0. (See also sysconf(3).)
SEE ALSO mmap(2)
B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128-129 and 389-391.
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 2008-04-22 MSYNC(2)
The following is taken from some production code:
#ifdef LOCK_LOCKF
#ifdef HAVE_SYS_FILE_H
#include <sys/lockf.h>
#endif
#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
#define LOCK(file) fseek(file, 0L, 0), lockf(file, 1, 0L)
#define UNLOCK(file) fseek(file, 0L, 0),... (2 Replies)
I really can't understand why this programm doesn't work (on linux); it open mapped memory, changes one byte and write back to disk:
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include... (3 Replies)
Is there an 'easy' way to convert 32Bit code to 64Bit code. I have this benchmark i need to run on different machines and it would be nice if i could run it on the 64 bit machines ass wel.
The output when compiling(1) and running(2) are the following:
(1)
linux:/home/user1/subbench/heapsort #... (7 Replies)
Command to fresh the memory !
Some time during some load on the AIX system memory will get hang and will not respond for any new process.
Can you please helper me with command to fresh the memory to avoid that hanging on the memory. (3 Replies)