Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935500AbYBUXG7 (ORCPT ); Thu, 21 Feb 2008 18:06:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754662AbYBUXGt (ORCPT ); Thu, 21 Feb 2008 18:06:49 -0500 Received: from smtp-out113.alice.it ([85.37.17.113]:4882 "EHLO smtp-out113.alice.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbYBUXGs (ORCPT ); Thu, 21 Feb 2008 18:06:48 -0500 X-Greylist: delayed 976 seconds by postgrey-1.27 at vger.kernel.org; Thu, 21 Feb 2008 18:06:47 EST Date: Thu, 21 Feb 2008 23:50:49 +0000 From: Giuliano Pochini To: Lukas Hejtmanek Cc: Pavel Machek , linux-kernel@vger.kernel.org, zdenek.kabelac@gmail.com Subject: Re: Disk schedulers Message-Id: <20080221235049.3742484f.pochini@shiny.it> In-Reply-To: <20080220184842.GA4867@ics.muni.cz> References: <20080214162104.GA5347@ics.muni.cz> <20080216172048.GB3979@ucw.cz> <20080220184842.GA4867@ics.muni.cz> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.10.14; powerpc-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 21 Feb 2008 22:49:23.0593 (UTC) FILETIME=[00D95790:01C874DC] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1757 Lines: 66 On Wed, 20 Feb 2008 19:48:42 +0100 Lukas Hejtmanek wrote: > On Sat, Feb 16, 2008 at 05:20:49PM +0000, Pavel Machek wrote: > > Is cat /dev/zero > file enough to reproduce this? > > yes. > > > > ext3 filesystem? > > yes. > > > Will cat /etc/passwd work while machine is unresponsive? > > yes. > > while find does not work: > time find / > / > /etc > /etc/manpath.config > /etc/update-manager > /etc/update-manager/release-upgrades > /etc/gshadow- > /etc/inputrc > /etc/openalrc > /etc/bonobo-activation > /etc/bonobo-activation/bonobo-activation-config.xml > /etc/gnome-vfs-2.0 > /etc/gnome-vfs-2.0/modules > /etc/gnome-vfs-2.0/modules/obex-module.conf > /etc/gnome-vfs-2.0/modules/extra-modules.conf > /etc/gnome-vfs-2.0/modules/theme-method.conf > /etc/gnome-vfs-2.0/modules/font-method.conf > /etc/gnome-vfs-2.0/modules/default-modules.conf > ^C > > real 0m7.982s > user 0m0.003s > sys 0m0.000s > > > i.e., it took 8 seconds to list just 17 dir entries. It also happens when I'm writing to a slow external disk. Documentation/block/biodoc.txt says: "Per-queue granularity unplugging (still a Todo) may help reduce some of the concerns with just a single tq_disk flush approach. Something like blk_kick_queue() to unplug a specific queue (right away ?) or optionally, all queues, is in the plan." If I understand correctly, there is only one "plug" in common for all devices. It may explain why when a queue is full, access to other devices is also blocked. -- Giuliano. -- 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/