From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754650AbYKTITd (ORCPT ); Thu, 20 Nov 2008 03:19:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752833AbYKTITY (ORCPT ); Thu, 20 Nov 2008 03:19:24 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:42992 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752293AbYKTITY (ORCPT ); Thu, 20 Nov 2008 03:19:24 -0500 Date: Thu, 20 Nov 2008 13:49:24 +0530 From: Bharata B Rao To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Srivatsa Vaddagiri , Peter Zijlstra , Dhaval Giani Subject: Re: [PATCH] sched: Don't allow priority switch to realtime when the task doesn't belong to init_task_group and when CONFIG_RT_GROUP_SCHED isn't set Message-ID: <20081120081924.GB4349@in.ibm.com> Reply-To: bharata@linux.vnet.ibm.com References: <20081120061854.GA4349@in.ibm.com> <20081120075829.GA21785@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081120075829.GA21785@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 20, 2008 at 08:58:29AM +0100, Ingo Molnar wrote: > > hm, another option would be, instead of denying something (which > denial might not even be noticed by the app) that the app clearly has > enough privilege to request - to just act upon it and move the task to > the init_task_group? Thought about that option, but decided against it because: - The task was started in a group which is not "equipped" to handle rt tasks (no rt_rq for the group because CONFIG_RT_GROUP_SCHED=n). So the task shouldn't have been started in such a group in the first place. - We could move the task silently to init_task_group (which is kind of done now with the task being placed in init_task_group's rq), but that's not what a user would have expected when he started a task under a group. Also, silently moving the task to init_task_group would cause confusion later when the task drops the RT privilege. As Dhaval is asking in the other thread, which group do we move it to now ? Regards, Bharata.