From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753198AbbJTJc6 (ORCPT ); Tue, 20 Oct 2015 05:32:58 -0400 Received: from terminus.zytor.com ([198.137.202.10]:49700 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775AbbJTJc4 (ORCPT ); Tue, 20 Oct 2015 05:32:56 -0400 Date: Tue, 20 Oct 2015 02:32:01 -0700 From: tip-bot for Luca Abeni Message-ID: Cc: peterz@infradead.org, efault@gmx.de, luca.abeni@unitn.it, wanpeng.li@linux.intel.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@zytor.com, torvalds@linux-foundation.org, juri.lelli@arm.com, mingo@kernel.org Reply-To: wanpeng.li@linux.intel.com, efault@gmx.de, luca.abeni@unitn.it, peterz@infradead.org, juri.lelli@arm.com, mingo@kernel.org, torvalds@linux-foundation.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, hpa@zytor.com In-Reply-To: <1444982781-15608-1-git-send-email-luca.abeni@unitn.it> References: <1444982781-15608-1-git-send-email-luca.abeni@unitn.it> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/deadline: Fix migration of SCHED_DEADLINE tasks Git-Commit-ID: 5aa5050787f449e7eaef2c5ec93c7b357aa7dcdc 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: 5aa5050787f449e7eaef2c5ec93c7b357aa7dcdc Gitweb: http://git.kernel.org/tip/5aa5050787f449e7eaef2c5ec93c7b357aa7dcdc Author: Luca Abeni AuthorDate: Fri, 16 Oct 2015 10:06:21 +0200 Committer: Ingo Molnar CommitDate: Tue, 20 Oct 2015 10:13:36 +0200 sched/deadline: Fix migration of SCHED_DEADLINE tasks Commit: 9d5142624256 ("sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target") broke select_task_rq_dl() and find_lock_later_rq(), because it introduced a comparison between the local task's deadline and dl.earliest_dl.curr of the remote queue. However, if the remote runqueue does not contain any SCHED_DEADLINE task its earliest_dl.curr is 0 (always smaller than the deadline of the local task) and the remote runqueue is not selected for pushing. As a result, if an application creates multiple SCHED_DEADLINE threads, they will never be pushed to runqueues that do not already contain SCHED_DEADLINE tasks. This patch fixes the issue by checking if dl.dl_nr_running == 0. Signed-off-by: Luca Abeni Signed-off-by: Peter Zijlstra (Intel) Cc: Juri Lelli Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Wanpeng Li Fixes: 9d5142624256 ("sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target") Link: http://lkml.kernel.org/r/1444982781-15608-1-git-send-email-luca.abeni@unitn.it Signed-off-by: Ingo Molnar --- kernel/sched/deadline.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index fc8f010..142df26 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1066,8 +1066,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) int target = find_later_rq(p); if (target != -1 && - dl_time_before(p->dl.deadline, - cpu_rq(target)->dl.earliest_dl.curr)) + (dl_time_before(p->dl.deadline, + cpu_rq(target)->dl.earliest_dl.curr) || + (cpu_rq(target)->dl.dl_nr_running == 0))) cpu = target; } rcu_read_unlock(); @@ -1417,7 +1418,8 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) later_rq = cpu_rq(cpu); - if (!dl_time_before(task->dl.deadline, + if (later_rq->dl.dl_nr_running && + !dl_time_before(task->dl.deadline, later_rq->dl.earliest_dl.curr)) { /* * Target rq has tasks of equal or earlier deadline,