From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932444AbdIRPPh (ORCPT ); Mon, 18 Sep 2017 11:15:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:46338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752253AbdIRPPg (ORCPT ); Mon, 18 Sep 2017 11:15:36 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9EB721A2A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Mon, 18 Sep 2017 11:15:34 -0400 From: Steven Rostedt To: Byungchul Park 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: <20170918111534.4fcbf9fd@gandalf.local.home> In-Reply-To: <1505351119-1044-2-git-send-email-byungchul.park@lge.com> References: <1505351119-1044-1-git-send-email-byungchul.park@lge.com> <1505351119-1044-2-git-send-email-byungchul.park@lge.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -- 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; > }