Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759824AbXFUUSj (ORCPT ); Thu, 21 Jun 2007 16:18:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753342AbXFUUSb (ORCPT ); Thu, 21 Jun 2007 16:18:31 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:48619 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752894AbXFUUSa (ORCPT ); Thu, 21 Jun 2007 16:18:30 -0400 Date: Thu, 21 Jun 2007 22:18:16 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Chuck Ebbert , Jarek Poplawski , Miklos Szeredi , chris@atlee.ca, linux-kernel@vger.kernel.org, tglx@linutronix.de, akpm@linux-foundation.org Subject: Re: [BUG] long freezes on thinkpad t60 Message-ID: <20070621201816.GE22303@elte.hu> References: <20070620093612.GA1626@ff.dom.local> <20070621073031.GA683@elte.hu> <20070621160817.GA22897@elte.hu> <467AAB04.2070409@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1030 Lines: 24 * Linus Torvalds wrote: > No, the cache line arbitration doesn't know anything about "locked" vs > "unlocked" instructions (it could, but there really is no point). > > The real issue is that locked instructions on x86 are serializing, > which makes them extremely slow (compared to just a write), and then > by being slow they effectively just make the window for another core > bigger. > > IOW, it doesn't "fix" anything, it just hides the bug with timing. yeah. I think Linux is i think the only OS on the planet that is using the movb trick for unlock, it even triggered a hardware erratum ;) So it might surprise some hw makers who might rely on the heuristics that each critical section lock and unlock is a LOCK-ed instruction. 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/