MSYNC(2) Linux Programmer's Manual MSYNC(2)NAME
msync - synchronize a file with a memory map
int msync(const void *start, size_t length, int flags);
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).
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
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.
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
Standard C Library (libc, -lc)
msync(void *addr, size_t len, int flags);
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.
If any errors occur, -1 is returned and errno is set to indicate the error. Otherwise, a 0 value is returned.
msync() will fail if:
[EINVAL] addr is not a multiple of the hardware page size.
[EINVAL] len is too large, or less than 1.
[EINVAL] flags combined MS_ASYNC with another flag, which is not permitted.
[EIO] An I/O error occurred while writing to the file system.
SEE ALSO madvise(2), mincore(2), mprotect(2), munmap(2)HISTORY
The msync() function first appeared in 4.4BSD.
BSD June 21, 1994 BSD
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