From: Andi Kleen <ak@suse.de>
To: Dave Engebretsen <engebret@vnet.ibm.com>
Cc: justincarlson@cmu.edu, Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org, anton@samba.org, davidm@hpl.hp.com,
ak@suse.de
Subject: Re: Memory Barrier Definitions
Date: Wed, 8 May 2002 17:49:25 +0200 [thread overview]
Message-ID: <20020508174924.A32610@wotan.suse.de> (raw)
In-Reply-To: <E175BY8-0008S4-00@the-village.bc.nu> <1020809750.13627.24.camel@gs256.sp.cs.cmu.edu> <3CD89247.8ECB01A4@vnet.ibm.com> <3CD943CE.296717DF@vnet.ibm.com>
On Wed, May 08, 2002 at 10:27:10AM -0500, Dave Engebretsen wrote:
> I am curious what the definition of memory barriers is for IA64, Sparc,
> and x86-64.
>
> >From what I can tell, sparc and x86-64 are like alpha and map directly
> to the existing mb, wmb, and rmb semantics, incluing ordering between
> system memory and I/O space. Is that an accurate assesment?
I don't think it is true for alpha, but it is true
for x86-64. x86-64 by default has strong ordering for most loads/stores.
It is possible to use weak ordering for special marked stores. For that
there are special read and write and read/write barriers which apply
to all memory (not distinction between io space and other memory). In
addition there is a way to mark special memory areas as write combining and
some other settings, but that is ordered by the normal barriers too.
-Andi
next prev parent reply other threads:[~2002-05-08 15:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-07 19:07 Dave Engebretsen
2002-05-07 19:49 ` Alan Cox
2002-05-07 19:53 ` Dave Engebretsen
2002-05-07 20:27 ` Alan Cox
2002-05-07 21:23 ` Dave Engebretsen
2002-05-07 22:15 ` justincarlson
2002-05-08 2:49 ` Dave Engebretsen
2002-05-08 13:54 ` Justin Carlson
2002-05-08 15:27 ` Dave Engebretsen
2002-05-08 15:49 ` Andi Kleen [this message]
2002-05-08 17:07 ` David Mosberger
2002-05-09 7:36 ` Rusty Russell
2002-05-09 8:01 ` Keith Owens
2002-05-09 15:00 ` David Mosberger
2002-05-13 3:26 ` Rusty Russell
2002-05-13 16:36 ` David Mosberger
2002-05-13 16:50 ` Linus Torvalds
2002-05-13 17:53 ` David Mosberger
2002-05-13 23:28 ` Rusty Russell
2002-05-07 22:57 ` Anton Blanchard
2002-05-13 18:16 ` Jesse Barnes
2002-05-09 11:33 Manfred Spraul
2002-05-09 19:38 ` Dave Engebretsen
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