From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933464AbdKPApW (ORCPT ); Wed, 15 Nov 2017 19:45:22 -0500 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:49475 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753923AbdKPApC (ORCPT ); Wed, 15 Nov 2017 19:45:02 -0500 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Thu, 16 Nov 2017 09:44:52 +0900 From: Byungchul Park To: peterz@infradead.org, mingo@kernel.org, rostedt@goodmis.org Cc: tglx@linutronix.de, raistlin@linux.it, linux-kernel@vger.kernel.org, juri.lelli@gmail.com, bristot@redhat.com, kernel-team@lge.com Subject: Re: [PATCH v3 2/2] sched/deadline: Initialize cp->elements[].cpu to an invalid value Message-ID: <20171116004452.GC4394@X58A-UD3R> References: <1510616805-15380-1-git-send-email-byungchul.park@lge.com> <1510616805-15380-2-git-send-email-byungchul.park@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1510616805-15380-2-git-send-email-byungchul.park@lge.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 On Tue, Nov 14, 2017 at 08:46:45AM +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 migrations. Therefore, it has to return an invalid value > e.i. -1 in that case. Hello Daniel, Did you also ack on this one? Hello Ingo and Peter, Could you consider this series? Thanks, Byungchul > Signed-off-by: Byungchul Park > Acked-by: Steven Rostedt (VMware) > --- > 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 empty 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; > } > -- > 1.9.1