From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932075Ab3BMHyy (ORCPT ); Wed, 13 Feb 2013 02:54:54 -0500 Received: from mail-bk0-f43.google.com ([209.85.214.43]:61292 "EHLO mail-bk0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757219Ab3BMHyw (ORCPT ); Wed, 13 Feb 2013 02:54:52 -0500 MIME-Version: 1.0 In-Reply-To: <20130213061853.GA4043@brouette> References: <1360675195-4017-1-git-send-email-vincent.guittot@linaro.org> <20130213061853.GA4043@brouette> Date: Wed, 13 Feb 2013 08:54:50 +0100 Message-ID: Subject: Re: [PATCH] sched: fix env->src_cpu for active migration From: Vincent Guittot To: Damien Wyart Cc: linux-kernel@vger.kernel.org, linaro-dev@lists.linaro.org, peterz@infradead.org, mingo@kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Damien, Thanks for the test and the feedback. Could you send me the sched_domain configuration of your machine with the kernel that boots on your machine ? It's available in /proc/sys/kernel/sched_domain/cpu*/ This should not have any impact on your machine but it looks like it have one. Regards, Vincent On 13 February 2013 07:18, Damien Wyart wrote: > Hi, > > I tested this on top of 3.8-rc7 and this made the machine (x86_64, Core > i7 920) unable to boot (very early as nothing at all is displayed on > screen). Nothing in the kernel log (after booting with a working > kernel). > > Double-checked by just backing out only this patch and this made the > machine boot again. > > Damien > >> need_active_balance uses env->src_cpu which is set only if there is more >> than 1 task on the run queue. We must set the src_cpu field unconditionnally >> otherwise the test "env->src_cpu > env->dst_cpu" will always fail if there is >> only 1 task on the run queue >> >> Signed-off-by: Vincent Guittot >> --- >> kernel/sched/fair.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 81fa536..32938ea 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -5044,6 +5044,10 @@ redo: >> >> ld_moved = 0; >> lb_iterations = 1; >> + >> + env.src_cpu = busiest->cpu; >> + env.src_rq = busiest; >> + >> if (busiest->nr_running > 1) { >> /* >> * Attempt to move tasks. If find_busiest_group has found >> @@ -5052,8 +5056,6 @@ redo: >> * correctly treated as an imbalance. >> */ >> env.flags |= LBF_ALL_PINNED; >> - env.src_cpu = busiest->cpu; >> - env.src_rq = busiest; >> env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); >> >> update_h_load(env.src_cpu);