Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030324AbXALUwK (ORCPT ); Fri, 12 Jan 2007 15:52:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030331AbXALUwK (ORCPT ); Fri, 12 Jan 2007 15:52:10 -0500 Received: from hobbit.corpit.ru ([81.13.94.6]:20768 "EHLO hobbit.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030324AbXALUwJ (ORCPT ); Fri, 12 Jan 2007 15:52:09 -0500 Message-ID: <45A7F4F2.2080903@tls.msk.ru> Date: Fri, 12 Jan 2007 23:52:02 +0300 From: Michael Tokarev Organization: Telecom Service, JSC User-Agent: Icedove 1.5.0.8 (X11/20061128) MIME-Version: 1.0 To: Michael Tokarev CC: Chris Mason , Linus Torvalds , dean gaudet , Viktor , Aubrey , Hua Zhong , Hugh Dickins , linux-kernel@vger.kernel.org, hch@infradead.org, kenneth.w.chen@intel.com, akpm@osdl.org Subject: Re: O_DIRECT question References: <6d6a94c50701101857v2af1e097xde69e592135e54ae@mail.gmail.com> <45A629E9.70502@inbox.ru> <20070112202316.GA28400@think.oraclecorp.com> <45A7F396.4080600@tls.msk.ru> In-Reply-To: <45A7F396.4080600@tls.msk.ru> X-Enigmail-Version: 0.94.1.0 OpenPGP: id=4F9CF57E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 944 Lines: 27 Michael Tokarev wrote: [] > After all the explanations, I still don't see anything wrong with the > interface itself. O_DIRECT isn't "different semantics" - we're still > writing and reading some data. Yes, O_DIRECT and non-O_DIRECT usages > somewhat contradicts with each other, but there are other ways to make > the two happy, instead of introducing alot of stupid, complex, and racy > code all over. By the way. I just ran - for fun - a read test of a raid array. Reading blocks of size 512kbytes, starting at random places on a 400Gb array, doing 64threads. O_DIRECT: 336.73 MB/sec. !O_DIRECT: 146.00 MB/sec. Quite a... difference here. Using posix_fadvice() does not improve it. /mjt - 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/