Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761084AbXJYDuU (ORCPT ); Wed, 24 Oct 2007 23:50:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752872AbXJYDuI (ORCPT ); Wed, 24 Oct 2007 23:50:08 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:38429 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752865AbXJYDuH (ORCPT ); Wed, 24 Oct 2007 23:50:07 -0400 Date: Wed, 24 Oct 2007 20:46:31 -0700 From: Arjan van de Ven To: Nick Piggin Cc: Linux Kernel Mailing List , Linus Torvalds , "Kleen, Andi" Subject: Re: Is gcc thread-unsafe? Message-ID: <20071024204631.7e7e3c47@laptopd505.fenrus.org> In-Reply-To: <200710251324.49888.nickpiggin@yahoo.com.au> References: <200710251324.49888.nickpiggin@yahoo.com.au> Organization: Intel X-Mailer: Claws Mail 3.0.2 (GTK+ 2.12.1; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1026 Lines: 29 On Thu, 25 Oct 2007 13:24:49 +1000 Nick Piggin wrote: > Hi, > > Andi spotted this exchange on the gcc list. I don't think he's > brought it up here yet, but it worries me enough that I'd like > to discuss it. > > Starts here > http://gcc.gnu.org/ml/gcc/2007-10/msg00266.html > > Concrete example here > http://gcc.gnu.org/ml/gcc/2007-10/msg00275.html > > Basically, what the gcc developers are saying is that gcc is > free to load and store to any memory location, so long as it > behaves as if the instructions were executed in sequence. > this optimization btw is a serious mis-optimization, it makes memory more dirty and causes cachelines to become unshared.... I'm sure it works great on microbenchmarks but it sucks bigtime for anything real - 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/