From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Marco Costalba" Subject: Re: [PATCH WIP] sha1-lookup: make selection of 'middle' less aggressive Date: Tue, 1 Jan 2008 10:01:21 +0100 Message-ID: References: <7vd4soa3cw.fsf@gitster.siamese.dyndns.org> <7vtzm08l9w.fsf@gitster.siamese.dyndns.org> <7vodc77t0o.fsf@gitster.siamese.dyndns.org> <20080101063616.GA21605@coredump.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: "Linus Torvalds" , "Junio C Hamano" , git@vger.kernel.org To: "Jeff King" X-From: git-owner@vger.kernel.org Tue Jan 01 10:01:56 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 1J9d0V-0005g2-64 for gcvg-git-2@gmane.org; Tue, 01 Jan 2008 10:01:55 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751765AbYAAJBX (ORCPT ); Tue, 1 Jan 2008 04:01:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751773AbYAAJBW (ORCPT ); Tue, 1 Jan 2008 04:01:22 -0500 Received: from rv-out-0910.google.com ([209.85.198.184]:52097 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749AbYAAJBW (ORCPT ); Tue, 1 Jan 2008 04:01:22 -0500 Received: by rv-out-0910.google.com with SMTP id k20so4849425rvb.1 for ; Tue, 01 Jan 2008 01:01:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=nLxIyADx8g9lT3vsiQzdfFeJNlPTpZM6Hf8v49TKGYI=; b=F+O5qnilQTHHekQLofhR/HCtrWY3ORsicGQQ0nIbGSYNtO4OjH3iCKTc6I0FepnLLrJN5tZS5kFRWRxRi+PIWLZqiAdRjdbdxVQgy3v/0a0GnxkD+TZTTKiaU0/hGIFdnruVWQbkYZYOyWGgxkKUsVe1G95PsUjfLtywevpnwZw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=ALyybAKv886DYn2IaaJvTBmzPt3RrWVsKXXfPrlZFt7UAF01ahVOzIy/QufgZiLVhBMPlGZ3iVfzXUl2vo0Wgg0pa+1Ay4I1CLazlXx5BqEunRjKqVhXbADl1ofP1zUFqamHX01aLDs49nTnJ7tUVKXMESJcs96XYEPF1JVOyNE= Received: by 10.141.36.10 with SMTP id o10mr1301620rvj.176.1199178081294; Tue, 01 Jan 2008 01:01:21 -0800 (PST) Received: by 10.141.76.1 with HTTP; Tue, 1 Jan 2008 01:01:21 -0800 (PST) In-Reply-To: Content-Disposition: inline Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Jan 1, 2008 9:40 AM, Marco Costalba wrote: > On Jan 1, 2008 7:36 AM, Jeff King wrote: > > > > The packfile is noticeably larger (55M versus 40M) > > Well 55M versus 40M is _only_ 27% of compression ratio. It means that > the compression algorithm is not so fundamental because the data is > already, how to say, well packaged. > I think zlib is a very good general purpose algorithm, but is main strength is to give good final file sizes, it is mainly intended for files that are seldom decompressed. For the use we do in git IMHO it would seem appropriate to look for algorithms used in the field of filesystem compression, where decompression penalty is a design goal. I know very little about this but I think among kernel people, expert and competent hackers should not be difficult to find, given that compressed filesystem are around from many years under linux/fs/ directory. Marco