From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262686AbTKRNhh (ORCPT ); Tue, 18 Nov 2003 08:37:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262707AbTKRNhh (ORCPT ); Tue, 18 Nov 2003 08:37:37 -0500 Received: from gprs147-139.eurotel.cz ([160.218.147.139]:18561 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S262686AbTKRNhe (ORCPT ); Tue, 18 Nov 2003 08:37:34 -0500 Date: Tue, 18 Nov 2003 14:38:04 +0100 From: Pavel Machek To: Jens Axboe Cc: Guillaume Chazarain , Linux Kernel Subject: Re: [PATCH] cfq + io priorities Message-ID: <20031118133804.GC662@elf.ucw.cz> References: <20031109113928.GN2831@suse.de> <20031113125427.GB643@openzaurus.ucw.cz> <20031117081407.GI888@suse.de> <20031118132634.GB470@elf.ucw.cz> <20031118133253.GK888@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031118133253.GK888@suse.de> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > At least idle class can not be used to hold important semaphore > > forever (even low-priority prosses receive enough time not to hold > > important semaphores too long)... I believe you should do the same (== > > get rid of idle class for now, and clearly state that realtime ones > > are not _guaranteed_ anything). > > That's not doing something about it, that's giving up... :-) Yes. That's what we do for scheduler, already. [And its better to give up than to have DoS security hole, right?] > You could allow idle prio to proceed, if it holds a resource that could > potentially block others. I guess you can't push this for 2.6. And notice that we use same solution for cpu scheduler, where solution is quite easy (with no hot-paths overhead). Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?]