msync(3C)                                                  msync(3C)


       NAME
             msync - synchronize memory with physical storage

       SYNOPSIS
             #include <sys/types.h>
             #include <sys/mman.h>
             int msync(caddr_t addr, size_t len, int flags);

       DESCRIPTION
             The function msync writes all modified copies of pages over
             the range [addr, addr + len) to their backing storage
             locations.  msync optionally invalidates any copies so that
             further references to the pages will be obtained by the system
             from their backing storage locations.  The backing storage for
             a modified MAP_SHARED mapping is the file the page is mapped
             to; the backing storage for a modified MAP_PRIVATE mapping is
             its swap area.

             flags is a bit pattern built from the following values:

                   MS_ASYNC  perform asynchronous writes

                   MS_SYNC   perform synchronous writes

                   MS_INVALIDATE
                             invalidate mappings

             If MS_ASYNC is set, msync returns immediately once all write
             operations are scheduled; if MS_SYNC is set, msync does not
             return until all write operations are completed.

             MS_INVALIDATE invalidates all cached copies of data in memory,
             so that further references to the pages will be obtained by
             the system from their backing storage locations.

             The effect of

                   msync(addr, len, flags)

             is equivalent to:

                   memcntl(addr, len, MC_SYNC, flags, 0, 0)

          Return Values
             Upon successful completion, the function msync returns 0;
             otherwise, it returns -1 and sets errno to indicate the error.


                           Copyright 1994 Novell, Inc.               Page 1

      msync(3C)                                                  msync(3C)


      REFERENCES
            memcntl(2), mmap(2), sysconf(3C)

      NOTICES
            msync should be used by programs that require a memory object
            to be in a known state, for example, in building transaction
            facilities.









































                          Copyright 1994 Novell, Inc.               Page 2