From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756283Ab1AKSsN (ORCPT ); Tue, 11 Jan 2011 13:48:13 -0500 Received: from mailout-de.gmx.net ([213.165.64.22]:39368 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1756121Ab1AKSsL (ORCPT ); Tue, 11 Jan 2011 13:48:11 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+zJ/9/59SzA0Mco9rZVHV4e0mQ9sD2bEO1UYOO48 VvIEUhp1qNT1N3 Subject: Re: [patch] Re: autogroup: sched_setscheduler() fails From: Mike Galbraith To: bharata@linux.vnet.ibm.com Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: <20110111171046.GL4772@in.ibm.com> References: <20110110091622.GF2772@in.ibm.com> <1294655388.8197.22.camel@marge.simson.net> <1294657154.2016.459.camel@laptop> <1294677746.8345.4.camel@marge.simson.net> <20110111171046.GL4772@in.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 11 Jan 2011 19:48:06 +0100 Message-ID: <1294771686.8006.15.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.30.1.2 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-01-11 at 22:40 +0530, Bharata B Rao wrote: > On Mon, Jan 10, 2011 at 05:42:26PM +0100, Mike Galbraith wrote: > > Index: linux-2.6/kernel/sched_autogroup.c > > =================================================================== > > --- linux-2.6.orig/kernel/sched_autogroup.c > > +++ linux-2.6/kernel/sched_autogroup.c > > @@ -73,6 +73,15 @@ static inline struct autogroup *autogrou > > ag->id = atomic_inc_return(&autogroup_seq_nr); > > ag->tg = tg; > > tg->autogroup = ag; > > +#ifdef CONFIG_RT_GROUP_SCHED > > + /* > > + * HACK: autogroup RT tasks run in the root task group. > > + * This fools __sched_setscheduler() into proceeding on > > + * so we can move the task to the appropriate runqueue > > + * upon scheduling policy change. > > + */ > > + tg->rt_bandwidth.rt_runtime = RUNTIME_INF; > > +#endif > > > > return ag; > > > > @@ -143,6 +152,15 @@ autogroup_move_group(struct task_struct > > autogroup_kref_put(prev); > > } > > > > +static inline void > > +autogroup_setscheduler(struct task_struct *p, int on_rq) > > +{ > > + if (p->sched_class->task_move_group) > > + p->sched_class->task_move_group(p, on_rq); > > + else > > + set_task_rq(p, task_cpu(p)); > > +} > > + > > IIUC, with the above changes you are actually queing the task into > rt_rq of an autogroup. But the task's autogroup interface > (/proc//autogroup) allows you to control the bandwidth of only > cfs_rq tasks, while the rt tasks in the group get RUNTIME_INF bandwidth. > > I think what we need is a real group change here (which is difficult I > think) and not just sched_class change. Unless I fscked up, set_task_rq() is the group change. As soon as the task's class changes, it'll be moved to the root_task_group. -Mike