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)
Check Out this Related Man Page
MSYNC(2) BSD System Calls Manual MSYNC(2)NAME
msync -- synchronize a mapped region
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/mman.h>
int
msync(void *addr, size_t len, int flags);
DESCRIPTION
The msync() system call writes modified whole pages back to the filesystem and updates the file modification time. Only those pages contain-
ing addr and len-1 succeeding locations will be examined.
The flags argument may be specified as follows:
MS_ASYNC Return immediately
MS_SYNC Perform synchronous writes
MS_INVALIDATE Invalidate all cached data
The MS_ASYNC flag is not permitted to be combined with other flags.
RETURN VALUES
If any errors occur, -1 is returned and errno is set to indicate the error. Otherwise, a 0 value is returned.
ERRORS
msync() will fail if:
[EBUSY] Some of the specified addresses are locked and MS_INVALIDATE is specified.
[EINVAL] addr is not a multiple of the hardware page size.
[EINVAL] len is too large, or less than 1.
[EINVAL] flags is invalid (e.g., it combines MS_ASYNC with another flag, which is not permitted).
[EIO] An I/O error occurs while writing to the file system.
[ENOMEM] The specified address range is outside of the address range of the process or includes an unmapped page.
LEGACY SYNOPSIS
#include <sys/types.h>
#include <sys/mman.h>
The include file <sys/types.h> is necessary.
SEE ALSO madvise(2), mincore(2), mprotect(2), munmap(2), compat(5)HISTORY
The msync() function first appeared in 4.4BSD.
BSD June 21, 1994 BSD
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)