From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938145AbXG0WIU (ORCPT ); Fri, 27 Jul 2007 18:08:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765708AbXG0WIN (ORCPT ); Fri, 27 Jul 2007 18:08:13 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:39068 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761697AbXG0WIM (ORCPT ); Fri, 27 Jul 2007 18:08:12 -0400 Subject: Re: swap-prefetch: A smart way to make good use of idle resources (was: updatedb) From: Arjan van de Ven To: Indan Zupancic Cc: Al Boldi , linux-kernel@vger.kernel.org In-Reply-To: <52449.81.207.0.53.1185573103.squirrel@secure.samage.net> References: <200707272243.02336.a1426z@gawab.com> <1185568498.2711.5.camel@laptopd505.fenrus.org> <52449.81.207.0.53.1185573103.squirrel@secure.samage.net> Content-Type: text/plain Organization: Intel International BV Date: Fri, 27 Jul 2007 15:06:14 -0700 Message-Id: <1185573974.2711.8.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.3 (2.10.3-1.fc7) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2007-07-27 at 23:51 +0200, Indan Zupanci > > also, they take up seek time (5 to 10 msec), so if you were to read > > something else at the time you get additional latency. > > If there's other disk activity swap prefetch shouldn't do much, so this isn't > really true. how do you know there will be other activity? You start the IO and that basically blacks out the disk for 5 to 10 ms. If the "real" IO gets submitted in that time you add latency. You cannot predict that IO happening or not happening. -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org