From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: Yet another base64 patch Date: Thu, 14 Apr 2005 10:02:55 -0700 Message-ID: <425EA23F.6010900@zytor.com> References: <425DEF64.60108@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: git@vger.kernel.org X-From: git-owner@vger.kernel.org Thu Apr 14 19:02:04 2005 Return-path: Received: from vger.kernel.org ([12.107.209.244]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DM7he-0000Ll-BZ for gcvg-git@gmane.org; Thu, 14 Apr 2005 19:00:30 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261555AbVDNRDo (ORCPT ); Thu, 14 Apr 2005 13:03:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261551AbVDNRDo (ORCPT ); Thu, 14 Apr 2005 13:03:44 -0400 Received: from terminus.zytor.com ([209.128.68.124]:24970 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S261555AbVDNRD0 (ORCPT ); Thu, 14 Apr 2005 13:03:26 -0400 Received: from [172.27.3.248] (c-67-169-23-106.hsd1.ca.comcast.net [67.169.23.106]) (authenticated bits=0) by terminus.zytor.com (8.13.1/8.13.1) with ESMTP id j3EH2uxo008507 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 14 Apr 2005 10:03:03 -0700 User-Agent: Mozilla Thunderbird 1.0.2-1.3.2 (X11/20050324) X-Accept-Language: en-us, en To: Linus Torvalds In-Reply-To: X-Spam-Status: No, score=-5.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on terminus.zytor.com Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Linus Torvalds wrote: > > So why is "base64" worse than the stock one? > > As mentioned, the "flat" version may be faster, but it really isn't an > option. 32000 objects is peanuts. Any respectable source tree may hit that > in a short time, and will break in horrible ways on many Linux > filesystems. > If it does, it's not because of n_link; see previous email. I have used ext2 filesystems with hundreds of thousands of files per directory back in 1996. It was slow but didn't break anything. The only filesystem I know of which has a 2^16 entry limit is FAT. > So you need at least a single level of subdirectory. > > What I don't get is why the stock hex version would be better than base64. > > I like the result, I just don't _understand_ it. The base64 version has 2^12 subdirectories instead of 2^8 (I just used 2 characters as the hash key just like the hex version.) So it ascerbates the performance penalty of subdirectory hashing. -hpa