Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755567AbeAHGPp (ORCPT + 1 other); Mon, 8 Jan 2018 01:15:45 -0500 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:35773 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751085AbeAHGPj (ORCPT ); Mon, 8 Jan 2018 01:15:39 -0500 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 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: [RESEND PATCH v3 2/2] sched/deadline: Initialize cp->elements[].cpu to an invalid value Date: Mon, 8 Jan 2018 15:14:41 +0900 Message-Id: <1515392081-32320-2-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1515392081-32320-1-git-send-email-byungchul.park@lge.com> References: <1515392081-32320-1-git-send-email-byungchul.park@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 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. Signed-off-by: Byungchul Park Acked-by: Steven Rostedt (VMware) Acked-by: Daniel Bristot de Oliveira --- 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