From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932820AbZHZBao (ORCPT ); Tue, 25 Aug 2009 21:30:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755250AbZHZBao (ORCPT ); Tue, 25 Aug 2009 21:30:44 -0400 Received: from thunk.org ([69.25.196.29]:49972 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754913AbZHZBan (ORCPT ); Tue, 25 Aug 2009 21:30:43 -0400 Date: Tue, 25 Aug 2009 21:30:43 -0400 From: Theodore Tso To: Jeff Shanab Cc: Rik van Riel , linux-kernel@vger.kernel.org Subject: Re: Starting a grad project that may change kernel VFS. Early research Re: Starting a grad project that may change kernel VFS. Early research Message-ID: <20090826013043.GB17684@mit.edu> Mail-Followup-To: Theodore Tso , Jeff Shanab , Rik van Riel , linux-kernel@vger.kernel.org References: <4A93428A.4070903@earthlink.net> <4A941F56.8060502@redhat.com> <4A9427C7.8020009@earthlink.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A9427C7.8020009@earthlink.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@mit.edu X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Something which I urge you to think about is whether optimizing du -s is really worth it; this is not at all obvious. If it's going to cost performance; if it's going to require non-backwards compatible changes to filesystems; if it means introducing changes to the semantics of hard links --- please *seriously* consider whether or not it's worth it. In what workload or use case is "du -s" something that gets done frequently? And is it really worth adding code complexity and slowing down much more common operations, such as writing files? If the goal is do a project that gets you a master's degree or a Ph.D., ok, fine; there are plenty of academic degrees and honors which are given for ideas that are completely impractical and/or useless in the real world. If your goal is to create a feature that will be accepted into mainline, then you need to provide a lot more justification that this is actually a good and worthwhile thing to do, and that the benefits outweigh the costs (in code complexity, long-term maintenance, performance regressions, etc.) - Ted