msync(3C)            COMPATIBILITY FUNCTIONS            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 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 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 pat-
     tern 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)

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

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

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












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