Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753769AbZGVBKG (ORCPT ); Tue, 21 Jul 2009 21:10:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753198AbZGVBKG (ORCPT ); Tue, 21 Jul 2009 21:10:06 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:45925 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751406AbZGVBKE (ORCPT ); Tue, 21 Jul 2009 21:10:04 -0400 Date: Tue, 21 Jul 2009 18:07:50 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Troy Moure cc: Krzysztof Oledzki , Greg KH , Linux Kernel Mailing List , Andrew Morton , stable@kernel.org, lwn@lwn.net, Ian Lance Taylor Subject: Re: Linux 2.6.27.27 In-Reply-To: Message-ID: References: <20090720040655.GA11940@kroah.com> <4A645A45.9060509@ans.pl> <20090720151008.GC10015@suse.de> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1237 Lines: 27 On Tue, 21 Jul 2009, Linus Torvalds wrote: > > Just out of curiosity, how did you find it? Now that I know where to look, > it's very obvious in the assembler diffs, but I didn't notice it until you > pointed it out just because there is so _much_ of the diffs... Ahh. I think I see how you found it. Looking at the diffs, there's only a few places where the number of instructions changed by a big fraction. And there's only _one_ place that has a factor-of-three difference (26 lines in the correct cases, and 7 lines in the wrong one). Clever. There's also a case in do_page_fault() where -fno-strict-overflow generates a _lot_ more instructions than the other cases (but not by a factor of three - but it expands 63 instructions to 100). I'm not seeing quite _why_ it does that, but it does various stupid things like multiply by 0x38 etc. But it doesn't look buggy, it just looks stupid. Or did you just brute-force it and spend a lot of time eyeballing things? Linus -- 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/