From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures Date: Wed, 15 Aug 2007 17:42:07 -0700 (PDT) Message-ID: References: <20070809131423.GA9927@shell.boston.redhat.com> <46C2D6F3.3070707@s5r6.in-berlin.de> <18115.35524.56393.347841@cargo.ozlabs.ibm.com> <20070816003948.GY9645@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Paul Mackerras , Satyam Sharma , Stefan Richter , Chris Snook , Linux Kernel Mailing List , linux-arch@vger.kernel.org, Linus Torvalds , netdev@vger.kernel.org, Andrew Morton , ak@suse.de, heiko.carstens@de.ibm.com, davem@davemloft.net, schwidefsky@de.ibm.com, wensong@linux-vs.org, horms@verge.net.au, wjiang@resilience.com, cfriesen@nortel.com, zlynx@acm.org, rpjday@mindspring.com, jesper.juhl@gmail.com, segher@kernel.crashing.org, Herbert Xu To: "Paul E. McKenney" Return-path: Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:56014 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S937318AbXHPAmK (ORCPT ); Wed, 15 Aug 2007 20:42:10 -0400 In-Reply-To: <20070816003948.GY9645@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 15 Aug 2007, Paul E. McKenney wrote: > Seems to me that we face greater chance of confusion without the > volatile than with, particularly as compiler optimizations become > more aggressive. Yes, we could simply disable optimization, but > optimization can be quite helpful. A volatile default would disable optimizations for atomic_read. atomic_read without volatile would allow for full optimization by the compiler. Seems that this is what one wants in many cases.