From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752770AbYDEOax (ORCPT ); Sat, 5 Apr 2008 10:30:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751890AbYDEOao (ORCPT ); Sat, 5 Apr 2008 10:30:44 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:40798 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751928AbYDEOan (ORCPT ); Sat, 5 Apr 2008 10:30:43 -0400 Date: Sat, 5 Apr 2008 20:10:43 +0530 From: Srivatsa Vaddagiri To: Ken Moffat Cc: Ingo Molnar , "Rafael J. Wysocki" , lkml , a.p.zijlstra@chello.nl, aneesh.kumar@linux.vnet.ibm.com, dhaval@linux.vnet.ibm.com, Balbir Singh , skumar@linux.vnet.ibm.com Subject: Re: Regression in gdm-2.18 since 2.6.24 Message-ID: <20080405144042.GB24075@linux.vnet.ibm.com> Reply-To: vatsa@linux.vnet.ibm.com References: <20080403191916.GA30864@deepthought> <20080404143701.GA13042@linux.vnet.ibm.com> <20080404153232.GC21753@deepthought> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080404153232.GC21753@deepthought> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 04, 2008 at 04:32:32PM +0100, Ken Moffat wrote: > > Just to confirm, are you saying you applied patch below on top of > > 2.6.25-rc8 and it solved your shutdown issues? > > > Yes. Thanks for confirming that the patch I sent was what you had tried and found it to fix your problem. That patch however is not something we want to apply for 2.6.25-rc8 (since it will worsen interactivity for other cases). Given that you seem to be seeing the problem even without CONFIG_GROUP_SCHED, only the second hunk of the patch seems to be making a difference for your problem i.e just the hunk below applied on 2.6.25-rc8 (to kernel/sched_fair.c) should fix your problem too: @@ -1145,7 +1145,7 @@ static void check_preempt_wakeup(struct * More easily preempt - nice tasks, while not making * it harder for + nice tasks. */ - if (unlikely(se->load.weight > NICE_0_LOAD)) + if (unlikely(se->load.weight != NICE_0_LOAD)) gran = calc_delta_fair(gran, &se->load); if (pse->vruntime + gran < se->vruntime) [The first hunk is a no-op under !CONFIG_GROUP_SCHED, since entity_is_task() is always 1 for !CONFIG_GROUP_SCHED] This second hunk changes how fast + or - niced tasks get preempted. 2.6.25-rc8 (Bad case): Sets preempt granularity for + niced tasks at 5ms (1 CPU) 2.6.25-rc8 + the hunk above (Good case): Sets preempt granularity for + niced tasks at >5ms So bumping up preempt granularity for + niced tasks seems to make things work for you. IMO the deeper problem lies somewhere else (perhaps is some race issue in gdm itself), which is easily exposed with 2.6.25-rc8 which lets + niced tasks be preempted quickly. To help validate this, can you let us know the result of tuning preempt granularity on native 2.6.25-rc8 (without any patches applied and CONFIG_GROUP_SCHED disabled)? # echo 100000000 > /proc/sys/kernel/sched_wakeup_granularity_ns To check if echo command worked, do: # cat /proc/sys/kernel/sched_wakeup_granularity_ns It should return 100000000. Now try shutting down thr' gdm and pls let me know if it makes a difference. -- Regards, vatsa