Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964937AbXAKDQX (ORCPT ); Wed, 10 Jan 2007 22:16:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751072AbXAKDQX (ORCPT ); Wed, 10 Jan 2007 22:16:23 -0500 Received: from smtp.osdl.org ([65.172.181.24]:51006 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750707AbXAKDQW (ORCPT ); Wed, 10 Jan 2007 22:16:22 -0500 Date: Wed, 10 Jan 2007 19:15:48 -0800 (PST) From: Linus Torvalds To: Aubrey cc: Hua Zhong , Hugh Dickins , linux-kernel@vger.kernel.org, hch@infradead.org, kenneth.w.chen@intel.com, akpm@osdl.org, mjt@tls.msk.ru Subject: Re: O_DIRECT question In-Reply-To: Message-ID: References: <6d6a94c50701101857v2af1e097xde69e592135e54ae@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1403 Lines: 33 On Wed, 10 Jan 2007, Linus Torvalds wrote: > > So don't use O_DIRECT. Use things like madvise() and posix_fadvise() > instead. Side note: the only reason O_DIRECT exists is because database people are too used to it, because other OS's haven't had enough taste to tell them to do it right, so they've historically hacked their OS to get out of the way. As a result, our madvise and/or posix_fadvise interfaces may not be all that strong, because people sadly don't use them that much. It's a sad example of a totally broken interface (O_DIRECT) resulting in better interfaces not getting used, and then not getting as much development effort put into them. So O_DIRECT not only is a total disaster from a design standpoint (just look at all the crap it results in), it also indirectly has hurt better interfaces. For example, POSIX_FADV_NOREUSE (which _could_ be a useful and clean interface to make sure we don't pollute memory unnecessarily with cached pages after they are all done) ends up being a no-op ;/ Sad. And it's one of those self-fulfilling prophecies. Still, I hope some day we can just rip the damn disaster out. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/