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Message-ID: <17423.32792.500628.226831@cargo.ozlabs.ibm.com>
Date: Thu, 9 Mar 2006 12:08:40 +1100
From: Paul Mackerras <paulus@samba.org>
To: Linus Torvalds <torvalds@osdl.org>
Cc: akpm@osdl.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
       mingo@redhat.com, Alan Cox <alan@redhat.com>, linuxppc64-dev@ozlabs.org
Subject: Re: [PATCH] Document Linux's memory barriers [try #2] 
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Linus Torvalds writes:

> > If you ask me, the need for mmiowb on some platforms merely shows that
> > those platforms' implementations of spinlocks and read*/write* are
> > buggy...
> 
> You could also state that same as
> 
> 	"If you ask me, the need for mmiowb on some platforms merely shows 
> 	 that those platforms perform like a bat out of hell, and I think 
> 	 they should be slower"
> 
> because the fact is, x86 memory barrier rules are just about optimal for 
> performance.

... and x86 mmiowb is a no-op.  It's not x86 that I think is buggy.

Paul.
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