From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: AAARGH bisection is hard (Re: [2.6.39 regression] X locks up hard right after logging in) Date: Thu, 12 May 2011 10:37:53 -0700 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, git@vger.kernel.org To: Andrew Lutomirski X-From: git-owner@vger.kernel.org Thu May 12 19:39:12 2011 Return-path: Envelope-to: gcvg-git-2@lo.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QKZqx-0002aq-57 for gcvg-git-2@lo.gmane.org; Thu, 12 May 2011 19:39:11 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758294Ab1ELRit convert rfc822-to-quoted-printable (ORCPT ); Thu, 12 May 2011 13:38:49 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:35403 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758281Ab1ELRiq convert rfc822-to-8bit (ORCPT ); Thu, 12 May 2011 13:38:46 -0400 Received: from mail-ew0-f46.google.com (mail-ew0-f46.google.com [209.85.215.46]) (authenticated bits=0) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p4CHcFpJ032410 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL); Thu, 12 May 2011 10:38:16 -0700 Received: by ewy4 with SMTP id 4so494563ewy.19 for ; Thu, 12 May 2011 10:38:13 -0700 (PDT) Received: by 10.14.13.66 with SMTP id a42mr289003eea.193.1305221893098; Thu, 12 May 2011 10:38:13 -0700 (PDT) Received: by 10.14.127.144 with HTTP; Thu, 12 May 2011 10:37:53 -0700 (PDT) In-Reply-To: X-Spam-Status: No, hits=-102.977 required=5 tests=AWL,BAYES_00,USER_IN_WHITELIST X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Thu, May 12, 2011 at 10:15 AM, Andrew Lutomirski wrot= e: > > OK, this sucks. =A0In the course of bisecting this, I've hit two othe= r > apparently unrelated bugs that prevent my from testing large numbers > of kernels. =A0Do I have two questions: > > 1. Anyone have any ideas from looking at the log? Nope, that doesn't look very helpful. > 2. =A0The !&$#@ bisection is skipping all over the place. =A0I've see= n > 2.6.37 versions and all manner of -rc's out of order. That's the _point_ of bisection. It jumps around. You can start off trying to pick points on my development tree, but I only have a hundred merges or so. You're going to start delving into the actual development versions very quickly. And if you don't do it early, bisection is going to be much much slower, because it's not going to pick half-way points. So bisection works so well exactly because it picks points that are far away from each other, and you should just totally ignore the version number. It's meaningless. Looking at it just confuses you. Don't do it. Now, "pick stable points" would obviously be nice, but that is going to have to be manual. You can certainly make some helper scripts, and that's where that "--first-parent" thing comes in. So if you want to, just use "git bisect reset" to the commit you want to test. If you think it's networking, for example, and you've bisected into there but aren't sure, do "gitk --bisect", find the point where I merge, and pick that (and my parent), and "git bisect reset" those points. That way you can verify that it's the networking merge (or verify that it isn't). Linus