From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nix Subject: Re: Git and GCC Date: Sat, 15 Dec 2007 00:18:37 +0000 Message-ID: <877ijg6c9u.fsf@hades.wkstn.nix> References: <998d0e4a0712071821o520a75c4lbcaae92256071f48@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "J.C. Pizarro" , Linus Torvalds , David Miller , gcc@gcc.gnu.org, git@vger.kernel.org To: Johannes Schindelin X-From: gcc-return-143003-gcc=m.gmane.org@gcc.gnu.org Sat Dec 15 01:19:17 2007 Return-path: Envelope-to: gcc@gmane.org Received: from sourceware.org ([209.132.176.174]) by lo.gmane.org with smtp (Exim 4.50) id 1J3KkN-0004Vx-B3 for gcc@gmane.org; Sat, 15 Dec 2007 01:19:15 +0100 Received: (qmail 16943 invoked by alias); 15 Dec 2007 00:18:55 -0000 Received: (qmail 16930 invoked by uid 22791); 15 Dec 2007 00:18:54 -0000 X-Spam-Check-By: sourceware.org Received: from 41-052.adsl.zetnet.co.uk (HELO mail.esperi.org.uk) (194.247.41.52) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sat, 15 Dec 2007 00:18:46 +0000 Received: from esperi.org.uk (nix@hades.wkstn.nix [192.168.14.18]) by mail.esperi.org.uk (8.12.11.20060614/8.12.11) with ESMTP id lBF0IcTq015582; Sat, 15 Dec 2007 00:18:38 GMT Received: (from nix@localhost) by esperi.org.uk (8.12.11.20060614/8.12.11/Submit) id lBF0Ibdq021331; Sat, 15 Dec 2007 00:18:37 GMT Emacs: indefensible, reprehensible, and fully extensible. In-Reply-To: (Johannes Schindelin's message of "Sat, 8 Dec 2007 12:24:00 +0000 (GMT)") User-Agent: Gnus/5.1008 (Gnus v5.10.8) XEmacs/21.5-b28 (linux) X-DCC-sonic.net-Metrics: hades 1117; Body=6 Fuz1=6 Fuz2=6 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Delivered-To: mailing list gcc@gcc.gnu.org Archived-At: On 8 Dec 2007, Johannes Schindelin said: > Hi, > > On Sat, 8 Dec 2007, J.C. Pizarro wrote: > >> On 2007/12/07, "Linus Torvalds" wrote: >> >> > SHA1 is almost totally insignificant on x86. It hardly shows up. But >> > we have a good optimized version there. >> >> If SHA1 is slow then why dont he contribute adding Haval160 (3 rounds) >> that it's faster than SHA1? And to optimize still more it with SIMD >> instructions in kernelspace and userland. > > He said SHA-1 is insignificant. Actually davem also said it *is* significant on SPARC. But of course J. C. Pizarro's suggested solution won't work because you can't just go around replacing SHA-1 in git with something else :) you could *add* new hashing methods, but you couldn't avoid SHA-1, and adding a new hashing method would bloat every object and every hash in objects like commits with an indication of which hashing method was in use. (But you know this.) >> 1. "Don't compress this repo but compact this uncompressed repo >> using minimal spanning forest and deltas" ... and then you do a git-gc. Oops, now what? ... or perhaps you want to look something up in the pack. Now you have to unpack a large hunk of the whole damn thing. >> 2. "After, compress this whole repo with LZMA (e.g. 48MiB) from 7zip before >> burning it to DVD for backup reasons or before replicating it to >> internet". > > Patches? ;-) Replicating a pack to the internet is almost invariably replicating *parts* of a pack anyway, which reduces to the problem with option 1 above... -- `The rest is a tale of post and counter-post.' --- Ian Rawlings describes USENET