From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751935AbeDFQD4 (ORCPT ); Fri, 6 Apr 2018 12:03:56 -0400 Received: from mail-io0-f177.google.com ([209.85.223.177]:42733 "EHLO mail-io0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751579AbeDFQDy (ORCPT ); Fri, 6 Apr 2018 12:03:54 -0400 X-Google-Smtp-Source: AIpwx4+FLxJYb5tyxqDeQXOnq9+qsjB4T2fZg3cQpJJyQWmmL5ushRUyACGr0YKAQVAmtJ7JA5R5qyQ8KdCsS1MHXv4= MIME-Version: 1.0 In-Reply-To: <95fe50be-cc8b-4345-7333-cdf656fad2a7@gmail.com> References: <20180324064627.GA10884@linaro.org> <6b151c56-9ead-7bbe-d1b7-b0e6d69c0d7f@arm.com> <796bbd7b-8512-7370-28c9-0f082dc3f287@gmail.com> <95fe50be-cc8b-4345-7333-cdf656fad2a7@gmail.com> From: Vincent Guittot Date: Fri, 6 Apr 2018 18:03:33 +0200 Message-ID: Subject: Re: Problem with commit 31e77c93e432 "sched/fair: Update blocked load when newly idle" To: Heiner Kallweit Cc: Dietmar Eggemann , "Peter Zijlstra (Intel)" , Ingo Molnar , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Heiner, On 30 March 2018 at 10:37, Heiner Kallweit wrote: > Am 30.03.2018 um 08:50 schrieb Vincent Guittot: >> On 29 March 2018 at 19:40, Heiner Kallweit wrote: >>> Am 29.03.2018 um 09:41 schrieb Vincent Guittot: >> >>>> >>>> I'm finally not so sure that i have the right set up to reproduce the >>>> problem as I haven't been able to reproduce it since. >>>> >>>> Heiner, >>>> >>>> How fast the problem happens on your board ? >>>> Are you doing anything specific on the console that trigger the problem ? >>>> >>> Hi Vincent, >>> >>> the lag when working on the console is constantly there, the "rcu_preempt >>> detected stalls" happens after several hours (so far always within 24h) >>> w/o any triggering event I would be aware of. It occured also when the >>> system was idle at that point in time. >> >> Ok, so I don't have the problem on my hikey as the console never lag >> on my setup. >> >> Can you send me the config of your kernel ? I'd like to check if you >> have enable something that could trigger such problem >> > Sure, he we go. I also add a system log. Thanks for the config. I have used it for my setup but I can't reproduce your regression. My platforms stay stable so I probably missing something. Are you facing similar problem with other platforms or only this celeron based platform ? I have reviewed the code but don't see any obvious place in the patch that can generate the problem. Nevertheless, would you mind to try the patch below ? It's a blind test to try to narrow the problem. Thanks --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0951d1c..e9835f2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9794,9 +9794,9 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) sd = rcu_dereference_check_sched_domain(this_rq->sd); if (sd) update_next_balance(sd, &next_balance); - rcu_read_unlock(); nohz_newidle_balance(this_rq); + rcu_read_unlock(); goto out; } -- 2.7.4 > > # > # Automatically generated file; DO NOT EDIT. > # Linux/x86 4.16.0-rc7 Kernel Configuration > # [snip]