From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755423AbbFSSC7 (ORCPT ); Fri, 19 Jun 2015 14:02:59 -0400 Received: from terminus.zytor.com ([198.137.202.10]:49327 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754114AbbFSSCx (ORCPT ); Fri, 19 Jun 2015 14:02:53 -0400 Date: Fri, 19 Jun 2015 11:02:09 -0700 From: tip-bot for Wanpeng Li Message-ID: Cc: torvalds@linux-foundation.org, wanpeng.li@linux.intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, juri.lelli@arm.com, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org, mingo@kernel.org, bp@alien8.de Reply-To: wanpeng.li@linux.intel.com, torvalds@linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, juri.lelli@arm.com, tglx@linutronix.de, akpm@linux-foundation.org, bp@alien8.de, mingo@kernel.org In-Reply-To: <1431496867-4194-3-git-send-email-wanpeng.li@linux.intel.com> References: <1431496867-4194-3-git-send-email-wanpeng.li@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target Git-Commit-ID: 9d514262425691dddf942edea8bc9919e66fe140 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: 9d514262425691dddf942edea8bc9919e66fe140 Gitweb: http://git.kernel.org/tip/9d514262425691dddf942edea8bc9919e66fe140 Author: Wanpeng Li AuthorDate: Wed, 13 May 2015 14:01:03 +0800 Committer: Ingo Molnar CommitDate: Fri, 19 Jun 2015 10:06:46 +0200 sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target This patch adds a check that prevents futile attempts to move DL tasks to a CPU with active tasks of equal or earlier deadline. The same behavior as commit 80e3d87b2c55 ("sched/rt: Reduce rq lock contention by eliminating locking of non-feasible target") for rt class. Signed-off-by: Wanpeng Li Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Juri Lelli Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1431496867-4194-3-git-send-email-wanpeng.li@linux.intel.com Signed-off-by: Ingo Molnar --- kernel/sched/deadline.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 1c4bc31..98f7871 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1012,7 +1012,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) (p->nr_cpus_allowed > 1)) { int target = find_later_rq(p); - if (target != -1) + if (target != -1 && + dl_time_before(p->dl.deadline, + cpu_rq(target)->dl.earliest_dl.curr)) cpu = target; } rcu_read_unlock(); @@ -1359,6 +1361,17 @@ 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, + later_rq->dl.earliest_dl.curr)) { + /* + * Target rq has tasks of equal or earlier deadline, + * retrying does not release any lock and is unlikely + * to yield a different result. + */ + later_rq = NULL; + break; + } + /* Retry if something changed. */ if (double_lock_balance(rq, later_rq)) { if (unlikely(task_rq(task) != rq || -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/