2012-11-15 12:06:41 +01:00
|
|
|
.\" $NetBSD: membar_ops.3,v 1.3 2011/04/28 11:56:26 wiz Exp $
|
2011-02-14 20:36:03 +01:00
|
|
|
.\"
|
|
|
|
|
.\" Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
|
|
|
|
|
.\" All rights reserved.
|
|
|
|
|
.\"
|
|
|
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
|
|
|
.\" by Jason R. Thorpe.
|
|
|
|
|
.\"
|
|
|
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
|
|
|
.\" modification, are permitted provided that the following conditions
|
|
|
|
|
.\" are met:
|
|
|
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
|
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
|
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
|
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
|
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
|
|
|
.\"
|
|
|
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
|
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
|
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
|
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
|
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
|
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
|
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
|
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
|
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
|
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
|
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
|
.\"
|
|
|
|
|
.Dd February 11, 2007
|
|
|
|
|
.Dt MEMBAR_OPS 3
|
|
|
|
|
.Os
|
|
|
|
|
.Sh NAME
|
|
|
|
|
.Nm membar_ops ,
|
|
|
|
|
.Nm membar_enter ,
|
|
|
|
|
.Nm membar_exit ,
|
|
|
|
|
.Nm membar_producer ,
|
|
|
|
|
.Nm membar_consumer ,
|
|
|
|
|
.Nm membar_sync
|
|
|
|
|
.Nd memory access barrier operations
|
|
|
|
|
.\" .Sh LIBRARY
|
|
|
|
|
.\" .Lb libc
|
|
|
|
|
.Sh SYNOPSIS
|
|
|
|
|
.In sys/atomic.h
|
|
|
|
|
.\"
|
|
|
|
|
.Ft void
|
|
|
|
|
.Fn membar_enter "void"
|
|
|
|
|
.Ft void
|
|
|
|
|
.Fn membar_exit "void"
|
|
|
|
|
.Ft void
|
|
|
|
|
.Fn membar_producer "void"
|
|
|
|
|
.Ft void
|
|
|
|
|
.Fn membar_consumer "void"
|
|
|
|
|
.Ft void
|
|
|
|
|
.Fn membar_sync "void"
|
|
|
|
|
.Sh DESCRIPTION
|
|
|
|
|
The
|
|
|
|
|
.Nm membar_ops
|
|
|
|
|
family of functions provide memory access barrier operations necessary
|
|
|
|
|
for synchronization in multiprocessor execution environments that have
|
|
|
|
|
relaxed load and store order.
|
|
|
|
|
.Pp
|
|
|
|
|
.Bl -tag -width "mem"
|
|
|
|
|
.It Fn membar_enter
|
2012-11-15 12:06:41 +01:00
|
|
|
Any store preceding
|
2011-02-14 20:36:03 +01:00
|
|
|
.Fn membar_enter
|
|
|
|
|
will reach global visibility before all loads and stores following it.
|
|
|
|
|
.Pp
|
|
|
|
|
.Fn membar_enter
|
|
|
|
|
is typically used in code that implements locking primitives to ensure
|
|
|
|
|
that a lock protects its data.
|
|
|
|
|
.It Fn membar_exit
|
|
|
|
|
All loads and stores preceding
|
|
|
|
|
.Fn membar_exit
|
|
|
|
|
will reach global visibility before any store that follows it.
|
|
|
|
|
.Pp
|
|
|
|
|
.Fn membar_exit
|
|
|
|
|
is typically used in code that implements locking primitives to ensure
|
|
|
|
|
that a lock protects its data.
|
|
|
|
|
.It Fn membar_producer
|
|
|
|
|
All stores preceding the memory barrier will reach global visibility
|
|
|
|
|
before any stores after the memory barrier reach global visibility.
|
|
|
|
|
.It Fn membar_consumer
|
|
|
|
|
All loads preceding the memory barrier will complete before any loads
|
|
|
|
|
after the memory barrier complete.
|
|
|
|
|
.It Fn 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.
|
|
|
|
|
.El
|
|
|
|
|
.Sh SEE ALSO
|
|
|
|
|
.Xr atomic_ops 3
|
|
|
|
|
.Sh HISTORY
|
|
|
|
|
The
|
|
|
|
|
.Nm membar_ops
|
|
|
|
|
functions first appeared in
|
|
|
|
|
.Nx 5.0 .
|
