From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: bit fields && data tearing Date: Mon, 08 Sep 2014 10:59:08 -0700 Message-ID: <540DEE6C.2060904@zytor.com> References: <20140712181328.GA8738@redhat.com> <54079B70.4050200@hurleysoftware.com> <1409785893.30640.118.camel@pasglop> <063D6719AE5E284EB5DD2968C1650D6D17487172@AcuExch.aculab.com> <1409824374.4246.62.camel@pasglop> <5408E458.3@zytor.com> <54090AF4.7060406@hurleysoftware.com> <54091B30.7080100@zytor.com> <5409D76D.2070203@hurleysoftware.com> <5409D9C0.7030403@zytor.com> <20140908185240.21f52ca0@alan.etchedpixels.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140908185240.21f52ca0@alan.etchedpixels.co.uk> Sender: linux-alpha-owner@vger.kernel.org To: One Thousand Gnomes Cc: Peter Hurley , Benjamin Herrenschmidt , David Laight , Jakub Jelinek , "linux-arch@vger.kernel.org" , Tony Luck , "linux-ia64@vger.kernel.org" , Oleg Nesterov , "linux-kernel@vger.kernel.org" , Paul Mackerras , "Paul E. McKenney" , "linuxppc-dev@lists.ozlabs.org" , Miroslav Franc , Richard Henderson , linux-alpha@vger.kernel.org List-Id: linux-arch.vger.kernel.org On 09/08/2014 10:52 AM, One Thousand Gnomes wrote: > On Fri, 05 Sep 2014 08:41:52 -0700 > "H. Peter Anvin" wrote: > >> On 09/05/2014 08:31 AM, Peter Hurley wrote: >>> >>> Which is a bit ironic because I remember when Digital had a team >>> working on emulating native x86 apps on Alpha/NT. >>> >> >> Right, because the x86 architecture was obsolete and would never scale... > > Talking about "not scaling" can anyone explain how a "you need to use > set_bit() and friends" bug report scaled into a hundred message plus > discussion about ambiguous properties of processors (and nobody has > audited all the embedded platforms we support yet, or the weirder ARMs) > and a propsal to remove Alpha support. > > Wouldn't it be *much* simpler to do what I suggested in the first place > and use the existing intended for purpose, deliberately put there, > functions for atomic bitops, because they are fast on sane processors and > they work on everything else. > > I think the whole "removing Alpha EV5" support is basically bonkers. Just > use set_bit in the tty layer. Alpha will continue to work as well as it > always has done and you won't design out support for any future processor > that turns out not to do byte aligned stores. > > Alan > Is *that* what we are talking about? I was added to this conversation in the middle where it had already generalized, so I had no idea. -hpa From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.10]:58307 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbaIHR77 (ORCPT ); Mon, 8 Sep 2014 13:59:59 -0400 Message-ID: <540DEE6C.2060904@zytor.com> Date: Mon, 08 Sep 2014 10:59:08 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: bit fields && data tearing References: <20140712181328.GA8738@redhat.com> <54079B70.4050200@hurleysoftware.com> <1409785893.30640.118.camel@pasglop> <063D6719AE5E284EB5DD2968C1650D6D17487172@AcuExch.aculab.com> <1409824374.4246.62.camel@pasglop> <5408E458.3@zytor.com> <54090AF4.7060406@hurleysoftware.com> <54091B30.7080100@zytor.com> <5409D76D.2070203@hurleysoftware.com> <5409D9C0.7030403@zytor.com> <20140908185240.21f52ca0@alan.etchedpixels.co.uk> In-Reply-To: <20140908185240.21f52ca0@alan.etchedpixels.co.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: One Thousand Gnomes Cc: Peter Hurley , Benjamin Herrenschmidt , David Laight , Jakub Jelinek , "linux-arch@vger.kernel.org" , Tony Luck , "linux-ia64@vger.kernel.org" , Oleg Nesterov , "linux-kernel@vger.kernel.org" , Paul Mackerras , "Paul E. McKenney" , "linuxppc-dev@lists.ozlabs.org" , Miroslav Franc , Richard Henderson , linux-alpha@vger.kernel.org Message-ID: <20140908175908.yB3zRNbVSht8o2ZS8f2xfKq5aYUqk3QcP1R8-o1lFtw@z> On 09/08/2014 10:52 AM, One Thousand Gnomes wrote: > On Fri, 05 Sep 2014 08:41:52 -0700 > "H. Peter Anvin" wrote: > >> On 09/05/2014 08:31 AM, Peter Hurley wrote: >>> >>> Which is a bit ironic because I remember when Digital had a team >>> working on emulating native x86 apps on Alpha/NT. >>> >> >> Right, because the x86 architecture was obsolete and would never scale... > > Talking about "not scaling" can anyone explain how a "you need to use > set_bit() and friends" bug report scaled into a hundred message plus > discussion about ambiguous properties of processors (and nobody has > audited all the embedded platforms we support yet, or the weirder ARMs) > and a propsal to remove Alpha support. > > Wouldn't it be *much* simpler to do what I suggested in the first place > and use the existing intended for purpose, deliberately put there, > functions for atomic bitops, because they are fast on sane processors and > they work on everything else. > > I think the whole "removing Alpha EV5" support is basically bonkers. Just > use set_bit in the tty layer. Alpha will continue to work as well as it > always has done and you won't design out support for any future processor > that turns out not to do byte aligned stores. > > Alan > Is *that* what we are talking about? I was added to this conversation in the middle where it had already generalized, so I had no idea. -hpa