MEMBAR(9)

NAME
membar_enter, membar_exit, membar_producer, membar_consumer, membar_sync - memory access barrier operations

SYNOPSIS
#include <sys/atomic.h>
void
membar_enter(void);
void
membar_exit(void);
void
membar_producer(void);
void
membar_consumer(void);
void
membar_sync(void);

DESCRIPTION
The membar set of functions provide an interface for issuing memory barrier access operations with respect to multiple processors in the system.

membar_enter()
    Any store preceding membar_enter() will reach global visibility before all loads and stores following it.

    membar_enter() is typically used in code that implements locking primitives to ensure that a lock protects its data.

membar_exit()
    All loads and stores preceding membar_exit() will reach global visibility before any store that follows it.

    membar_exit() is typically used in code that implements locking primitives to ensure that a lock protects its data.

membar_producer()
    All stores preceding the memory barrier will reach global visibility before any stores after the memory barrier reach global visibility.

membar_consumer()
    All loads preceding the memory barrier will complete before any loads after the memory barrier complete.

membar_sync()
    All loads and stores preceding the memory barrier will complete and reach global visibility before any loads and stores after the memory barrier complete and reach global visibility.

CONTEXT
membar_enter(), membar_exit(), membar_producer(), membar_consumer(), membar_sync() can all be called during autoconf, from process context, or from interrupt context.

HISTORY
The membar functions first appeared in NetBSD 5.0 and OpenBSD 5.5.