linux-kernel - Re: [rfc][patch] i386: remove comment about barriers

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Message-ID: <alpine.LFD.0.999.0709290909580.3579@woody.linux-foundation.org>
Date:	Sat, 29 Sep 2007 09:11:10 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Nick Piggin <npiggin@...e.de>
cc:	Paul McKenney <paulmck@...ibm.com>,
	David Howells <dhowells@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: [rfc][patch] i386: remove comment about barriers



On Sat, 29 Sep 2007, Nick Piggin wrote:
> 
> OK this was going to be a quick patch, but after sleeping on it, I think
> it deserves a better analysis... I can prove the comment is incorrect with a
> test program, but I'm not as sure about my thinking that leads me to call it
> also misleading.

You're 100% right, that comment is total crap.

An lfence is *not* a memory barrier, it's just a read memory barrier. 

Although on some microarchitectures they may of course end up being the 
same thing.

			Linus
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