From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752795AbbEMGTP (ORCPT ); Wed, 13 May 2015 02:19:15 -0400 Received: from mga11.intel.com ([192.55.52.93]:25790 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751519AbbEMGTL (ORCPT ); Wed, 13 May 2015 02:19:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,419,1427785200"; d="scan'208";a="492930270" From: Wanpeng Li To: Ingo Molnar , Peter Zijlstra Cc: Juri Lelli , linux-kernel@vger.kernel.org, Wanpeng Li Subject: [PATCH v2 3/7] sched/deadline: reduce rq lock contention by eliminating locking of non-feasible target Date: Wed, 13 May 2015 14:01:03 +0800 Message-Id: <1431496867-4194-3-git-send-email-wanpeng.li@linux.intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1431496867-4194-1-git-send-email-wanpeng.li@linux.intel.com> References: <1431496867-4194-1-git-send-email-wanpeng.li@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch adds 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 --- v1 -> v2: * add check in find_lock_later_rq() 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 4303af2..e49b1e6 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(); @@ -1360,6 +1362,17 @@ 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 || -- 1.9.1