BARRIER(3) BSD Library Functions Manual BARRIER(3)

NAME
     OOSSMMeemmoorryyBBaarrrriieerr - memory barrier to order loads and stores

LLIIBBRRAARRYY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##iinncclluuddee <>

     void
     OOSSMMeemmoorryyBBaarrrriieerr(void);

DESCRIPTION
     OOSSMMeemmoorryyBBaarrrriieerr() strictly orders memory accesses in a weakly ordered
     memory model such as with PowerPC, by creating a barrier.  All loads and
     stores executed in sequential program order before the barrier will com-
     plete with respect to the memory coherence mechanism, before any load or
     store executed after the barrier.  Used with an atomic operation, the
     barrier can be used to create custom synchronization protocols as an
     alternative to the spinlock or queue/dequeue operations.  Note that this
     barrier does not order uncached loads and stores.  On a uniprocessor, the
     barrier operation is typically optimized into a nop.

SEE ALSO
     atomic(3), atomicqueue(3), spinlock(3)

Darwin                           May 26, 2004                           Darwin