From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: Bizarre missing changes (git bug?) Date: Tue, 29 Jul 2008 08:50:02 -0700 (PDT) Message-ID: References: <8502DF7C-5303-49E8-8C67-F837343E2F0C@gmail.com> <200807260512.40088.zippel@linux-m68k.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Tim Harper , git@vger.kernel.org To: Roman Zippel X-From: git-owner@vger.kernel.org Tue Jul 29 17:54:46 2008 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1KNrWy-0005Ex-Q1 for gcvg-git-2@gmane.org; Tue, 29 Jul 2008 17:54:33 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752298AbYG2Pxc (ORCPT ); Tue, 29 Jul 2008 11:53:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752083AbYG2Pxc (ORCPT ); Tue, 29 Jul 2008 11:53:32 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:60310 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbYG2Pxc (ORCPT ); Tue, 29 Jul 2008 11:53:32 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id m6TFr1X2029734 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 29 Jul 2008 08:53:03 -0700 Received: from localhost (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id m6TFr1nK008439; Tue, 29 Jul 2008 08:53:01 -0700 In-Reply-To: User-Agent: Alpine 1.10 (LFD 962 2008-03-14) X-Spam-Status: No, hits=-3.41 required=5 tests=AWL,BAYES_00 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 Tue, 29 Jul 2008, Roman Zippel wrote: > > I'm not dismissing it, but your focus is on how to get this result. No, you misunderstand. My focus is really on one single thing: - performance with a smaller focus on the fact that I simply don't see how it's _possible_ to do better than our current all-or-nothing approach of simplification (eg either extreme simplification or none at all: nothing or --full-history). So here's my challenge again, which you seem to have TOTALLY MISSED. Make this be fast: time sh -c "git log | head" nothing else matters. If you can make that one be fast, I'm happy. And that "| head" is really very fundamentally important. The important thing from a performance standpoint is not how long the _whole_ "log" takes. The important thing is how fast it _feels_, and that is directly tied to how fast it starts outputting the data. Put another way: I _know_ how to simplify things. Trust me, Roman. That's not the problem. But doing it incrementally is really really hard, to the point that I actually believe that it is impossible to do. And doing it after-the-fact is simply not interesting. We could trivially (well, _fairly_ trivially) do it when we do the topology sort. But I have long long tried to teach people _not_ to do the topo sort inside the core git machinery, exactly because it is a horrid thing from an interactivity standpoint. In fact, you can see what I'm talking about by trying --topo-order in the above timing test. Really. Just _try_ it. And if you still don't understand what I'm talking about, I don't know what to say. > > And quite frankly, I've seen that behaviour from you before, when it comes > > to other things. > > What exact behaviour is that? That I dare to disagree with you? No. The fact that you like arguing _pointlessly_, and just being abrasive, without actually helping or understanding the big picture. I'm thinking back on the whole scheduler thing. You weren't arguing with _me_, but you had the same modus operandi. Linus