From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lutomirski Subject: Re: AAARGH bisection is hard (Re: [2.6.39 regression] X locks up hard right after logging in) Date: Fri, 13 May 2011 09:39:14 -0400 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: Linus Torvalds X-From: linux-kernel-owner@vger.kernel.org Fri May 13 15:39:49 2011 Return-path: Envelope-to: glk-linux-kernel-3@lo.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QKsan-0005vT-5q for glk-linux-kernel-3@lo.gmane.org; Fri, 13 May 2011 15:39:45 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933122Ab1EMNjh convert rfc822-to-quoted-printable (ORCPT ); Fri, 13 May 2011 09:39:37 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:52877 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933092Ab1EMNjf convert rfc822-to-8bit (ORCPT ); Fri, 13 May 2011 09:39:35 -0400 Received: by pzk9 with SMTP id 9so1170810pzk.19 for ; Fri, 13 May 2011 06:39:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:in-reply-to:references:from :date:x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; bh=mGCQ/+/NaE+xFPIPa2CBgfDMznjr6VHgGqn3EO2eh50=; b=K8U8DM3DQDzqbgOg8O1xktOJbTcvJ+puAvr0vP+uYab10HskO8VkdsFXHUrWxp266f AwHO0WdBloHOlf7TLWX6tWz4qFRe/60JgW7devCs/+0P39KhWAoXvLY3+wLyZXoWhLyi wuakxh83+8S6HFv3qseZSoPtG48RCKFRfKPnU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=g8smaR+x9vmYW3WJSZxpg//lDRMp99nMqYsat5AXonzeUkGi4YkefvBOTuDaRPIuhl NDwM0VkflDLxT1niqALV1fxjjZtLAczDlfzT5kULskOPkJWxH9kTPGwh68rhPZrNVouN NgD5Hvues8lvHGoY2JFOyzOCmr6Wt4qrolEqw= Received: by 10.68.48.168 with SMTP id m8mr2246221pbn.113.1305293974098; Fri, 13 May 2011 06:39:34 -0700 (PDT) Received: by 10.68.41.197 with HTTP; Fri, 13 May 2011 06:39:14 -0700 (PDT) In-Reply-To: X-Google-Sender-Auth: v-59R5pg1k7NOho4jAexC06Mqxk Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: [resend because the Android gmail client apparently generates HTML emails even for plain text] On Thu, May 12, 2011 at 1:37 PM, Linus Torvalds wrote: > On Thu, May 12, 2011 at 10:15 AM, Andrew Lutomirski wr= ote: >> >> OK, this sucks. =A0In the course of bisecting this, I've hit two oth= er >> 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 se= en >> 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. > I actually had better results looking at the version number, saying "blech", and running git merge v2.6.38. (git bisect good gets a little confused if I feed it the merge result, but I can just lie.) Anyway, I must have made a mistake somewhere. The regression is in drm (presumably i915) and it has a new thread now. --Andy