From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J.C. Pizarro" Subject: Re: Git and GCC Date: Sat, 8 Dec 2007 03:21:40 +0100 Message-ID: <998d0e4a0712071821o520a75c4lbcaae92256071f48@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: "Linus Torvalds" , "David Miller" , gcc@gcc.gnu.org, git@vger.kernel.org X-From: git-owner@vger.kernel.org Sat Dec 08 03:22:05 2007 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 1J0pKO-0002nq-9W for gcvg-git-2@gmane.org; Sat, 08 Dec 2007 03:22:04 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753502AbXLHCVn (ORCPT ); Fri, 7 Dec 2007 21:21:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753368AbXLHCVn (ORCPT ); Fri, 7 Dec 2007 21:21:43 -0500 Received: from wr-out-0506.google.com ([64.233.184.233]:57219 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752116AbXLHCVm (ORCPT ); Fri, 7 Dec 2007 21:21:42 -0500 Received: by wr-out-0506.google.com with SMTP id c49so750897wra for ; Fri, 07 Dec 2007 18:21:41 -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:mime-version:content-type:content-transfer-encoding:content-disposition; bh=PZT/ph6TQAO1aaJ/mJsyL3syWihJc/oJZ1uC+mLD7Cw=; b=WhSQAqzrYf0eK22yGXMHXbVkUj4udSO1dva3DHOnucW9rkeNIInTtV9eX0zGGjggmyh0OJpHKQAp8yd6lIyCyYNQ83lgai6/wOzaHhHQIhbQYQeV9Trzq/ZtSiAxSZOQWVrHY8FtX/0KlYb/zgwtfU/hXR4bcFS9/6Su8F5rQzQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=xrw1sJKFoB9RhEkaEdCZcoBYFc2UctRB5Fyi0UEOu6QEY7ZamXTk0ibuGsuewPGfwoefJJ/0eMlMf+rY501Md891rXGbVLofR3SpxC1Ud6uuapjbqMQdQdlOMzxJvVSbascNAmkotn0f1ZSn967U/xRWymWUr4rHFLrXL/Np7JA= Received: by 10.70.49.4 with SMTP id w4mr874283wxw.1197080500623; Fri, 07 Dec 2007 18:21:40 -0800 (PST) Received: by 10.70.54.17 with HTTP; Fri, 7 Dec 2007 18:21:40 -0800 (PST) Content-Disposition: inline Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On 2007/12/07, "Linus Torvalds" wrote: > On Fri, 7 Dec 2007, David Miller wrote: > > > > Also I could end up being performance limited by SHA, it's not very > > well tuned on Sparc. It's been on my TODO list to code up the crypto > > unit support for Niagara-2 in the kernel, then work with Herbert Xu on > > the userland interfaces to take advantage of that in things like > > libssl. Even a better C/asm version would probably improve GIT > > performance a bit. > > I doubt yu can use the hardware support. Kernel-only hw support is > inherently broken for any sane user-space usage, the setup costs are just > way way too high. To be useful, crypto engines need to support direct user > space access (ie a regular instruction, with all state being held in > normal registers that get saved/restored by the kernel). > > > Is SHA a significant portion of the compute during these repacks? > > I should run oprofile... > > 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. > > zlib tends to be a lot more noticeable (especially the uncompression: it > may be faster than compression, but it's done _so_ much more that it > totally dominates). > > Linus It's better 1. "Don't compress this repo but compact this uncompressed repo using minimal spanning forest and deltas" 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". J.C.Pizarro "the noiser"