MSYNC(2) BSD System Calls Manual MSYNC(2)NAMEmsync — 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 filesys‐
tem and updates the file modification time. Only those pages containing
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.
ERRORSmsync() 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 ALSOmadvise(2), mincore(2), mprotect(2), munmap(2), compat(5)HISTORY
The msync() function first appeared in 4.4BSD.
BSD June 21, 1994 BSD
