BARRIER(3) BSD Library Functions Manual BARRIER(3)NAME
OSMemoryBarrier — memory barrier to order loads and stores
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <libkern/OSAtomic.h>
void
OSMemoryBarrier(void);
DESCRIPTIONOSMemoryBarrier() 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 ALSOatomic(3), spinlock(3)Darwin May 26, 2004 Darwin
