From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754232AbaEHKnR (ORCPT ); Thu, 8 May 2014 06:43:17 -0400 Received: from terminus.zytor.com ([198.137.202.10]:33146 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753376AbaEHKnP (ORCPT ); Thu, 8 May 2014 06:43:15 -0400 Date: Thu, 8 May 2014 03:42:14 -0700 From: tip-bot for Jason Low Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, preeti@linux.vnet.ibm.com, peterz@infradead.org, jason.low2@hp.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, preeti@linux.vnet.ibm.com, peterz@infradead.org, tglx@linutronix.de, jason.low2@hp.com In-Reply-To: <1398725155-7591-2-git-send-email-jason.low2@hp.com> References: <1398725155-7591-2-git-send-email-jason.low2@hp.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Fix updating rq-> max_idle_balance_cost and rq->next_balance in idle_balance() Git-Commit-ID: 0e5b5337f0da073e1f17aec3c322ea7826975d0d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 0e5b5337f0da073e1f17aec3c322ea7826975d0d Gitweb: http://git.kernel.org/tip/0e5b5337f0da073e1f17aec3c322ea7826975d0d Author: Jason Low AuthorDate: Mon, 28 Apr 2014 15:45:54 -0700 Committer: Ingo Molnar CommitDate: Wed, 7 May 2014 11:51:36 +0200 sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance() The following commit: e5fc66119ec9 ("sched: Fix race in idle_balance()") can potentially cause rq->max_idle_balance_cost to not be updated, even when load_balance(NEWLY_IDLE) is attempted and the per-sd max cost value is updated. Preeti noticed a similar issue with updating rq->next_balance. In this patch, we fix this by making sure we still check/update those values even if a task gets enqueued while browsing the domains. Signed-off-by: Jason Low Reviewed-by: Preeti U Murthy Signed-off-by: Peter Zijlstra Cc: morten.rasmussen@arm.com Cc: aswin@hp.com Cc: daniel.lezcano@linaro.org Cc: alex.shi@linaro.org Cc: efault@gmx.de Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1398725155-7591-2-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7570dd9..0fdb96d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6653,6 +6653,7 @@ static int idle_balance(struct rq *this_rq) int this_cpu = this_rq->cpu; idle_enter_fair(this_rq); + /* * We must set idle_stamp _before_ calling idle_balance(), such that we * measure the duration of idle_balance() as idle time. @@ -6705,14 +6706,16 @@ static int idle_balance(struct rq *this_rq) raw_spin_lock(&this_rq->lock); + if (curr_cost > this_rq->max_idle_balance_cost) + this_rq->max_idle_balance_cost = curr_cost; + /* - * While browsing the domains, we released the rq lock. - * A task could have be enqueued in the meantime + * While browsing the domains, we released the rq lock, a task could + * have been enqueued in the meantime. Since we're not going idle, + * pretend we pulled a task. */ - if (this_rq->cfs.h_nr_running && !pulled_task) { + if (this_rq->cfs.h_nr_running && !pulled_task) pulled_task = 1; - goto out; - } if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* @@ -6722,9 +6725,6 @@ static int idle_balance(struct rq *this_rq) this_rq->next_balance = next_balance; } - if (curr_cost > this_rq->max_idle_balance_cost) - this_rq->max_idle_balance_cost = curr_cost; - out: /* Is there a task of a high priority class? */ if (this_rq->nr_running != this_rq->cfs.h_nr_running &&