From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shawn O. Pearce" Subject: Re: [PATCH 0/4] Honor core.deltaBaseCacheLimit during index-pack Date: Tue, 15 Jul 2008 04:19:29 +0000 Message-ID: <20080715041929.GC2432@spearce.org> References: <20080713011512.GB31050@spearce.org> <1216001267-33235-1-git-send-email-spearce@spearce.org> <20080714031242.GA14542@spearce.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Johannes Schindelin , Nicolas Pitre , Junio C Hamano , git@vger.kernel.org, Stephan Hennig , Andreas Ericsson To: Jakub Narebski X-From: git-owner@vger.kernel.org Tue Jul 15 06:20:32 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 1KIc1d-0004Om-DA for gcvg-git-2@gmane.org; Tue, 15 Jul 2008 06:20:29 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750990AbYGOETa (ORCPT ); Tue, 15 Jul 2008 00:19:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751067AbYGOETa (ORCPT ); Tue, 15 Jul 2008 00:19:30 -0400 Received: from george.spearce.org ([209.20.77.23]:50252 "EHLO george.spearce.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870AbYGOETa (ORCPT ); Tue, 15 Jul 2008 00:19:30 -0400 Received: by george.spearce.org (Postfix, from userid 1001) id 73F073836B; Tue, 15 Jul 2008 04:19:29 +0000 (UTC) Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Jakub Narebski wrote: > Johannes Schindelin writes: > > On Mon, 14 Jul 2008, Shawn O. Pearce wrote: > > > > The only other alternative I can come up with is to change pack-objects > > > (or at least its defaults) so we don't generate these massive delta > > > chains. But there are already packs in the wild that use these chains, > > > resulting in performance problems for clients. > > > > But the long chains make the pack actually as efficient as it is... > > Perhaps Shawn thought here about limiting delta chain not by its > *length*, but by its *size* (as required when unpacking last object > in a delta chanin). > > What do you think about this idea? I was talking about that. Or at least thinking it. But its not a good solution, as Dscho points out those long chains is what makes the pack file such a powerful source code compressor. IMHO the right solution is to continue to allow these long chains, especially since they are typically used for the older, less often accessed objects, and use bounded caching where necessary in the readers to avoid unpacking costs. We already have a bounded cache for the random access case used by most programs. What we missed was the bounded cache in index-pack, and my 4 patch series is an attempt to define that. -- Shawn.