msync(3C)               LIBRARY FUNCTIONS               msync(3C)



NAME
     msync - synchronize memory with physical storage

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

DESCRIPTION
     The function msync writes all modified copies of pages  over
     the  range [addr, addr + len) to their backing storage loca-
     tions.  msync optionally  invalidates  any  copies  so  that
     further references to the pages will be obtained by the sys-
     tem from  their  backing  storage  locations.   The  backing
     storage  for  a  modified MAPSHARED mapping is the file the
     page is mapped  to;  the  backing  storage  for  a  modified
     MAPPRIVATE  mapping  is its swap area.  flags is a bit pat-
     tern built from the following values:
            MSASYNC        perform asynchronous writes
            MSSYNC         perform synchronous writes
            MSINVALIDATE   invalidate mappings
     If MSASYNC is set, msync returns immediately once all write
     operations  are scheduled; if MSSYNC is set, msync does not
     return   until   all   write   operations   are   completed.
     MSINVALIDATE  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, MCSYNC, flags, 0, 0)

RETURN VALUE
     Upon successful completion, the  function  msync  returns  a
     value  of  0;  otherwise,  it returns a value of -1 and sets
     errno to indicate an error.

ERRORS
     See memcntl(2).

NOTES
     msync should be used  by  programs  that  require  a  memory
     object to be in a known state, for example in building tran-
     saction facilities.

SEE ALSO
     memcntl(2), mmap(2), sysconf(3C).










                                                                1