Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755624AbbDGXQN (ORCPT ); Tue, 7 Apr 2015 19:16:13 -0400 Received: from mga09.intel.com ([134.134.136.24]:54207 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755203AbbDGXQK (ORCPT ); Tue, 7 Apr 2015 19:16:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,540,1422950400"; d="scan'208";a="552443927" Date: Wed, 8 Apr 2015 06:57:56 +0800 From: Wanpeng Li To: Juri Lelli Cc: Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" , Wanpeng Li Subject: Re: [PATCH 3/7] sched/deadline: reduce rq lock contention by eliminating locking of non-feasible target Message-ID: <20150407225755.GA9966@kernel> Reply-To: Wanpeng Li References: <1428310399-13489-1-git-send-email-wanpeng.li@linux.intel.com> <1428310399-13489-3-git-send-email-wanpeng.li@linux.intel.com> <5523E01C.9020808@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5523E01C.9020808@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1579 Lines: 50 Hi Juri, On Tue, Apr 07, 2015 at 02:48:12PM +0100, Juri Lelli wrote: >Hi, > >On 06/04/2015 09:53, Wanpeng Li wrote: >> 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. >> > >This commit introduced also this kind of check in find_lock_lowest_rq(). >Don't we need something like this in find_lock_later_rq() as well? > Good point, will do. Great thanks for your review. :) Regards, Wanpeng Li >Thanks, > >- Juri > >> Signed-off-by: Wanpeng Li >> --- >> kernel/sched/deadline.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c >> index 3bd3158..b8b9355 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(); >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/