From mboxrd@z Thu Jan 1 00:00:00 1970 From: "C. Scott Ananian" Subject: Re: [PATCH] write-tree performance problems Date: Wed, 20 Apr 2005 11:52:02 -0400 (EDT) Message-ID: References: <200504191250.10286.mason@suse.com> <200504192049.21947.mason@suse.com> <200504201122.35448.mason@suse.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: git@vger.kernel.org X-From: git-owner@vger.kernel.org Wed Apr 20 17:49:55 2005 Return-path: Received: from vger.kernel.org ([12.107.209.244]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DOHQt-0004Sj-6Z for gcvg-git@gmane.org; Wed, 20 Apr 2005 17:48:07 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261701AbVDTPwV (ORCPT ); Wed, 20 Apr 2005 11:52:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261700AbVDTPwV (ORCPT ); Wed, 20 Apr 2005 11:52:21 -0400 Received: from sincerity-forever.csail.mit.edu ([128.30.67.31]:42896 "EHLO sincerity-forever.csail.mit.edu") by vger.kernel.org with ESMTP id S261701AbVDTPwR (ORCPT ); Wed, 20 Apr 2005 11:52:17 -0400 Received: from catfish.lcs.mit.edu ([128.30.67.25] helo=cag.csail.mit.edu) by sincerity-forever.csail.mit.edu with esmtp (Exim 3.36 #1 (Debian)) id 1DOHUt-0000Z5-00; Wed, 20 Apr 2005 11:52:15 -0400 To: Linus Torvalds In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org On Wed, 20 Apr 2005, Linus Torvalds wrote: >> I was considering using a chunked representation for *all* files (not just >> blobs), which would avoid the original 'trees must reference other trees >> or they become too large' issue -- and maybe the performance issue you're >> referring to, as well? > No. The most common index file operation is reading, and that's the one > that has to be _fast_. And it is - it's a single "mmap" and some parsing. OK, sure. But how 'bout chunking trees? Are you grown happy with the new trees-reference-other-trees paradigm, or is there a deep longing in your heart for the simplicity of 'trees-reference-blobs-period'? I'm fairly certain that chunking could get you the space-savings you need without multi-level trees, if the simplicity of that is still appealing. Not necessarily for rev.1 of the chunking code, but I'm curious as to whether it's still of interest at all. I don't know exactly how far ingrained multilevel trees have become since they were adopted. --scott Japan explosion BLUEBIRD Honduras jihad D5 SLBM Diplomat overthrow JMTIDE CABOUNCE AMTHUG ESODIC Kennedy AVBRANDY CLOWER mail drop PHOENIX ( http://cscott.net/ )