DragonFly On-Line Manual Pages

---

MSYNC(2) DragonFly System Calls Manual MSYNC(2)
NAME
 msync -- synchronize a mapped region
LIBRARY
 Standard C Library (libc, -lc)
SYNOPSIS
 #include <sys/types.h>
 #include <sys/mman.h>
 int
 msync(void *addr, size_t len, int flags);
DESCRIPTION
 The msync() system call writes any modified pages back to the filesystem
 and updates the file modification time. If len is 0, all modified pages
 within the region containing addr will be flushed; if len is non-zero,
 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
RETURN VALUES
 The msync() function returns the value 0 if successful; otherwise the
 value -1 is returned and the global variable errno is set to indicate the
 error.
ERRORS
 msync() will fail if:
 [EINVAL] addr is not a multiple of the hardware page size.
 [EINVAL] len is too large or negative.
 [EINVAL] flags was both MS_ASYNC and MS_INVALIDATE. Only one
 of these flags is allowed.
 [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.
DragonFly 4.3 June 21, 1994 DragonFly 4.3

---