From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753611AbXGIIr6 (ORCPT ); Mon, 9 Jul 2007 04:47:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751370AbXGIIrt (ORCPT ); Mon, 9 Jul 2007 04:47:49 -0400 Received: from web32605.mail.mud.yahoo.com ([68.142.207.232]:22842 "HELO web32605.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751316AbXGIIrt (ORCPT ); Mon, 9 Jul 2007 04:47:49 -0400 X-YMail-OSG: tX3qQ1IVM1lCtNjpeYf.nh9osZLNFgBlt_Y4IH43EfDhs9JfKLd6VqCOpe.jmDztblHPniZ62MHm_OB.45UrWzOZLg-- X-RocketYMMF: knobi.rm Date: Mon, 9 Jul 2007 01:47:48 -0700 (PDT) From: Martin Knoblauch Reply-To: spamtrap@knobisoft.de Subject: Re: Understanding I/O behaviour To: Jesper Juhl Cc: linux-kernel@vger.kernel.org In-Reply-To: <9a8748490707081428p11a9b728m8cec7cc2a122d907@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-ID: <212660.59998.qm@web32605.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Jesper Juhl wrote: > On 05/07/07, Jesper Juhl wrote: > > On 05/07/07, Martin Knoblauch wrote: > > > Hi, > > > > > > > I'd suspect you can't get both at 100%. > > > > I'd guess you are probably using a 100Hz no-preempt kernel. Have > you > > tried a 1000Hz + preempt kernel? Sure, you'll get a bit lower > > overall throughput, but interactive responsiveness should be better > - > > if it is, then you could experiment with various combinations of > > CONFIG_PREEMPT, CONFIG_PREEMPT_VOLUNTARY, CONFIG_PREEMPT_NONE and > > CONFIG_HZ_1000, CONFIG_HZ_300, CONFIG_HZ_250, CONFIG_HZ_100 to see > > what gives you the best balance between throughput and interactive > > responsiveness (you could also throw CONFIG_PREEMPT_BKL and/or > > CONFIG_NO_HZ, but I don't think the impact will be as significant > as > > with the other options, so to keep things simple I'd leave those > out > > at first) . > > > > I'd guess that something like CONFIG_PREEMPT_VOLUNTARY + > CONFIG_HZ_300 > > would probably be a good compromise for you, but just to see if > > there's any effect at all, start out with CONFIG_PREEMPT + > > CONFIG_HZ_1000. > > > > I'm currious, did you ever try playing around with CONFIG_PREEMPT* > and > CONFIG_HZ* to see if that had any noticable impact on interactive > performance and stuff like logging into the box via ssh etc...? > > -- > Jesper Juhl > Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html > Plain text mails only, please http://www.expita.com/nomime.html > > Hi Jesper, my initial kernel was voluntary@100HZ. I have switched to 300HZ, but have not observed much difference. The config is now: config-2.6.22-rc7:# CONFIG_PREEMPT_NONE is not set config-2.6.22-rc7:CONFIG_PREEMPT_VOLUNTARY=y config-2.6.22-rc7:# CONFIG_PREEMPT is not set config-2.6.22-rc7:CONFIG_PREEMPT_BKL=y Cheers ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de