Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758990Ab1CDHk3 (ORCPT ); Fri, 4 Mar 2011 02:40:29 -0500 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:41911 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754878Ab1CDHk1 (ORCPT ); Fri, 4 Mar 2011 02:40:27 -0500 Date: Fri, 4 Mar 2011 12:55:17 +0530 From: Balbir Singh To: Yong Zhang Cc: "linux-kernel@vger.kernel.org" , Ingo Molnar , Peter Zijlstra , Srivatsa Vaddagiri , Bharata B Rao Subject: Re: [BUGFIX][PATCH] Fix sched rt group scheduling when hierachy is enabled Message-ID: <20110304072517.GC2868@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20110303113435.GA2868@balbir.in.ibm.com> <20110303140551.GA20677@zhy> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1055 Lines: 28 * Yong Zhang [2011-03-04 11:43:16]: > On Thu, Mar 3, 2011 at 11:29 PM, Balbir Singh wrote: > > No, not really :) It is required, it is a backup check to see if we > > have queued tasks, rt_time of 0 and the runqueue is not throttled, why > > should it be dequeued? > > But I can't see where that kind of rt_rq is dequeued, mind pointing it out? > So here is what I saw 1. sched_dequeue_stack called from the dequeue path dequeues the queues and sets rt_nr_running to 0 2. Enqueuing fails because rt_throttled is set for the group_rq (parent who is throttled) 3. This causes further enqueue to fail, since rt_nr_running did not increment in step 2, eventually the timer decrements rt_time to 0 and the task is never picked up. -- Three Cheers, Balbir -- 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/