MSYNC(2) BSD Programmer's Manual MSYNC(2)
msync - synchronize a mapped region
msync(caddr_t addr, int len);
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 the pages containing addr and len succeeding locations will be exam-
ined. Any required synchronization of memory caches will also take place
at this time. Filesystem operations on a file that is mapped for shared
modifications are unpredictable except after an msync().
The following errors may be reported:
[EINVAL] The addr parameter was not page aligned.
[EINVAL] The addr parameter did not specify an address part of a
[EINVAL] The len parameter was negative.
[EIO] An I/O error occured while writing to the file system.
madvise(2), munmap(2), mprotect(2), mincore(2)
The msync() function first appeared in 4.4BSD.
4.4BSD June 21, 1994 1