From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936648AbdIZAtx (ORCPT ); Mon, 25 Sep 2017 20:49:53 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:39663 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935073AbdIZAtw (ORCPT ); Mon, 25 Sep 2017 20:49:52 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Tue, 26 Sep 2017 09:49:35 +0900 From: Byungchul Park To: Steven Rostedt Cc: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org, juri.lelli@gmail.com, kernel-team@lge.com Subject: Re: [PATCH v2 2/2] sched/deadline: Initialize cp->elements[].cpu to an invalid value Message-ID: <20170926004935.GL5994@X58A-UD3R> References: <1505351119-1044-1-git-send-email-byungchul.park@lge.com> <1505351119-1044-2-git-send-email-byungchul.park@lge.com> <20170918111534.4fcbf9fd@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170918111534.4fcbf9fd@gandalf.local.home> 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 On Mon, Sep 18, 2017 at 11:15:34AM -0400, Steven Rostedt wrote: > On Thu, 14 Sep 2017 10:05:19 +0900 > Byungchul Park wrote: > > > Currently, migrating tasks to cpu0 unconditionally happens when the > > heap is empty, since cp->elements[].cpu was initialized to 0(=cpu0). > > We have to distinguish between the empty case and cpu0 to avoid the > > unnecessary migrantions. Therefore, it has to return an invalid value > > e.i. -1 in that case. > > > > Looks good to me. > > Acked-by: Steven Rostedt (VMware) > > Peter, you back from LA? Can you review these and send them to Ingo? Hello Peter, could you check this patch? > > -- Steve > > > Signed-off-by: Byungchul Park > > --- > > kernel/sched/cpudeadline.c | 10 +++++++++- > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c > > index 9f02035..bcf903f 100644 > > --- a/kernel/sched/cpudeadline.c > > +++ b/kernel/sched/cpudeadline.c > > @@ -138,6 +138,12 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, > > int best_cpu = cpudl_maximum_cpu(cp); > > WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); > > > > + /* > > + * The heap tree is empry for now, just return. > > + */ > > + if (best_cpu == -1) > > + return 0; > > + > > if (cpumask_test_cpu(best_cpu, &p->cpus_allowed) && > > dl_time_before(dl_se->deadline, cpudl_maximum_dl(cp))) { > > if (later_mask) > > @@ -265,8 +271,10 @@ int cpudl_init(struct cpudl *cp) > > return -ENOMEM; > > } > > > > - for_each_possible_cpu(i) > > + for_each_possible_cpu(i) { > > + cp->elements[i].cpu = -1; > > cp->elements[i].idx = IDX_INVALID; > > + } > > > > return 0; > > }