From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from 87-104-106-3-dynamic-customer.profibernet.dk ([87.104.106.3]:33318 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932621Ab1IHMj0 (ORCPT ); Thu, 8 Sep 2011 08:39:26 -0400 Message-ID: <4E68B77D.10400@kernel.dk> Date: Thu, 08 Sep 2011 14:39:25 +0200 From: Jens Axboe MIME-Version: 1.0 Subject: Re: Linux I/O stack design question References: <1314880418.11001.6.camel@werner-t410> <1314908040.2091.14.camel@werner-t410> <4E5FE840.9040706@kernel.dk> <1314908867.2091.23.camel@werner-t410> <4E5FF57A.1040908@kernel.dk> <1315231292.2140.62.camel@werner-t410> In-Reply-To: <1315231292.2140.62.camel@werner-t410> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Werner Fischer Cc: Jeff Moyer , "fio@vger.kernel.org" On 2011-09-05 16:01, Werner Fischer wrote: > On Don, 2011-09-01 at 15:13 -0600, Jens Axboe wrote: >> [...] >> I mean that every device should plug in at the same place. There are >> definite up and down sides to plugging in at the stacking level and >> bypassing the IO scheduler. So you have to weight the pros and cons >> before doing that. We need to fix this. Drivers doing that lose out on >> other features in the name of a bit more performance, that's just not >> acceptable. > > I have updated the diagram according to all of your hints: > http://www.thomas-krenn.com/de/wikiDE/images/0/07/Linux-IO-Stack.png > > I had also some off-list discussion with Florian Haas, who convinced me > that the file systems are below of the page cache. I hope this is now > correct. Not sure I'd agree with that, I'd place the page cache between the fs and the storage layer. -- Jens Axboe