From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neal Kreitzinger Subject: how to analyze binary delta compression Date: Wed, 25 Apr 2012 16:15:32 -0500 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Wed Apr 25 23:15:54 2012 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1SN9Z2-00029V-QY for gcvg-git-2@plane.gmane.org; Wed, 25 Apr 2012 23:15:53 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759317Ab2DYVPs (ORCPT ); Wed, 25 Apr 2012 17:15:48 -0400 Received: from plane.gmane.org ([80.91.229.3]:49003 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759147Ab2DYVPr (ORCPT ); Wed, 25 Apr 2012 17:15:47 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1SN9Yu-0001zJ-7Y for git@vger.kernel.org; Wed, 25 Apr 2012 23:15:44 +0200 Received: from 67.63.162.200 ([67.63.162.200]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 Apr 2012 23:15:44 +0200 Received: from nkreitzinger by 67.63.162.200 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 Apr 2012 23:15:44 +0200 X-Injected-Via-Gmane: http://gmane.org/ X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: 67.63.162.200 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko/20120327 Thunderbird/11.0.1 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: I need to assess the delta compression efficiency of various types of binaries. Can I do it this way: (1) Run git diff between two versions of a binary and pipe the result to a file. (Sample different types of binaries and changes.) (2) Assess the output by size or format or content to determine how well it delta differenced? How would I determine this? What are good absolute delta sizes? What are good delta size ratios compared to total file size? Is the number of hunks in the delta important? (3) Compress the delta file with gzip (or something) and then assess the compression ratio? What is a good compression ratio? What are good delta compressed absolute sizes? What are good delta compressed relative sizes to total file size? I'm sure I may be missing some things here. I'm new to assessing delta compression efficiency of binaries in general, and specifically for git. Please advise. v/r, neal