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Date: Mon, 20 Aug 2007 09:15:11 -0400
From: Chris Snook <csnook@redhat.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Nick Piggin <piggin@cyberone.com.au>, Satyam Sharma <satyam@infradead.org>,
       Herbert Xu <herbert@gondor.apana.org.au>,
       Paul Mackerras <paulus@samba.org>, Christoph Lameter <clameter@sgi.com>,
       Ilpo Jarvinen <ilpo.jarvinen@helsinki.fi>,
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       heiko.carstens@de.ibm.com, David Miller <davem@davemloft.net>,
       schwidefsky@de.ibm.com, wensong@linux-vs.org, horms@verge.net.au,
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       rpjday@mindspring.com, jesper.juhl@gmail.com,
       segher@kernel.crashing.org
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all
 architectures
References: <18115.52863.638655.658466@cargo.ozlabs.ibm.com> <20070816053945.GB32442@gondor.apana.org.au> <18115.62741.807704.969977@cargo.ozlabs.ibm.com> <20070816070907.GA964@gondor.apana.org.au> <Pine.LNX.4.64.0708161743500.13267@kivilampi-30.cs.helsinki.fi> <46C4ABA5.9010804@redhat.com> <Pine.LNX.4.64.0708161319000.17777@schroedinger.engr.sgi.com> <18117.1287.779351.836552@cargo.ozlabs.ibm.com> <alpine.LFD.0.999.0708161953310.30176@woody.linux-foundation.org> <18117.6495.397597.582736@cargo.ozlabs.ibm.com> <20070817035342.GA14744@gondor.apana.org.au> <alpine.LFD.0.999.0708171142550.3666@enigma.security.iitk.ac.in> <46C55E90.7010407@yahoo.com.au> <alpine.LFD.0.999.0708171431150.3666@enigma.security.iitk.ac.in> <46C56ADF.8010501@cyberone.com.au> <alpine.LFD.0.999.0708171612440.3666@enigma.security.iitk.ac.in> <46C59717.4020108@cyberone.com.au> <alpine.LFD.0.999.0708170929580.30176@woody.linux-foundation.org>
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Linus Torvalds wrote:
> So the only reason to add back "volatile" to the atomic_read() sequence is 
> not to fix bugs, but to _hide_ the bugs better. They're still there, they 
> are just a lot harder to trigger, and tend to be a lot subtler.

What about barrier removal?  With consistent semantics we could optimize a fair 
amount of code.  Whether or not that constitutes "premature" optimization is 
open to debate, but there's no question we could reduce our register wiping in 
some places.

	-- Chris
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