From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH] pack-objects: use of version 3 delta is now optional. Date: Sun, 15 Oct 2006 11:57:44 -0700 (PDT) Message-ID: References: <7v4pu62ite.fsf@assigned-by-dhcp.cox.net> <7virim10rb.fsf@assigned-by-dhcp.cox.net> <7vac3xzbze.fsf@assigned-by-dhcp.cox.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Nicolas Pitre , git@vger.kernel.org X-From: git-owner@vger.kernel.org Sun Oct 15 20:58:32 2006 Return-path: Envelope-to: gcvg-git@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by ciao.gmane.org with esmtp (Exim 4.43) id 1GZBBn-0001vX-HI for gcvg-git@gmane.org; Sun, 15 Oct 2006 20:58:23 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030216AbWJOS6O (ORCPT ); Sun, 15 Oct 2006 14:58:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030224AbWJOS6O (ORCPT ); Sun, 15 Oct 2006 14:58:14 -0400 Received: from smtp.osdl.org ([65.172.181.4]:55263 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030216AbWJOS6O (ORCPT ); Sun, 15 Oct 2006 14:58:14 -0400 Received: from shell0.pdx.osdl.net (fw.osdl.org [65.172.181.6]) by smtp.osdl.org (8.12.8/8.12.8) with ESMTP id k9FIvjaX006606 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Sun, 15 Oct 2006 11:57:46 -0700 Received: from localhost (shell0.pdx.osdl.net [10.9.0.31]) by shell0.pdx.osdl.net (8.13.1/8.11.6) with ESMTP id k9FIvibl021318; Sun, 15 Oct 2006 11:57:45 -0700 To: Junio C Hamano In-Reply-To: <7vac3xzbze.fsf@assigned-by-dhcp.cox.net> X-Spam-Status: No, hits=-2.468 required=5 tests=AWL,OSDL_HEADER_SUBJECT_BRACKETED,PATCH_SUBJECT_OSDL X-Spam-Checker-Version: SpamAssassin 2.63-osdl_revision__1.95__ X-MIMEDefang-Filter: osdl$Revision: 1.155 $ X-Scanned-By: MIMEDefang 2.36 Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: On Sun, 15 Oct 2006, Junio C Hamano wrote: > > I think that is sensible. I also was thinking that we should > call the current one packv3 and the one with delta-base-offset > packv4. Quite frankly, I wonder if the pure "copy size extension" (aka "v3") thing is really worth it at all. I mean, seriously, how much does it buy us? A couple of bytes per every 64kB of delta copied? And the downside is that you can't re-use the deltas with old clients and/or you have to re-create a "v2" delta at run-time from a v3 delta by inflating, fixing and deflating it. So I would suggest: - call the delta-base-offset thing the "v3" pack format. - forget about the current "v3 delta" entirely. We might as well continue to support reading it, but there's no point in actually ever generating it. In other words, I think the current situation in top-of-master is the right situation. There's simply no point in adding code to convert v3 to v2 on the fly - even if it's not rocket science, it's just not _worth_ it. (You could also have the extended copy deltas in v3-only, and only send it to clients that you know supports it. However, the "convert to v2" format issue still rears its ugly head, and as a result I just don't think it's _ever_ worth it). Linus