Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755708AbYGITep (ORCPT ); Wed, 9 Jul 2008 15:34:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753462AbYGITef (ORCPT ); Wed, 9 Jul 2008 15:34:35 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:45641 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753998AbYGITee (ORCPT ); Wed, 9 Jul 2008 15:34:34 -0400 Date: Wed, 9 Jul 2008 21:34:04 +0200 From: Ingo Molnar To: Mike Travis Cc: Jeremy Fitzhardinge , "H. Peter Anvin" , Andrew Morton , "Eric W. Biederman" , Christoph Lameter , Jack Steiner , linux-kernel@vger.kernel.org Subject: Re: [RFC 00/15] x86_64: Optimize percpu accesses Message-ID: <20080709193404.GC4804@elte.hu> References: <20080709165129.292635000@polaris-admin.engr.sgi.com> <4874F30C.8020800@zytor.com> <4874F909.7060503@goop.org> <4874FEDF.90404@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4874FEDF.90404@sgi.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1230 Lines: 29 * Mike Travis wrote: > > This fragility makes me very nervous. It seems hard enough to get > > this stuff working with current tools; making it work over the whole > > range of supported tools looks like its going to be hard. > > (me too ;-) > > Once I get a solid version working with (at least) gcc-4.2.4, then > regression testing with older tools will be easier, or at least a > table of results can be produced. the problem is, we cannot just put it even into tip/master if there's no short-term hope of fixing a problem it triggers. gcc-4.2.3 is solid for me otherwise, for series of thousands of randomly built kernels. can we just leave out the zero-based percpu stuff safely and could i test the rest of your series - or are there dependencies? I think zero-based percpu, while nice in theory, is probably just a very small positive effect so it's not a life or death issue. (or is there any deeper, semantic reason why we'd want it?) Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/