From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE97CC5CFC0 for ; Mon, 18 Jun 2018 04:58:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71A9D20864 for ; Mon, 18 Jun 2018 04:58:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71A9D20864 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lge.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932710AbeFRE6f (ORCPT ); Mon, 18 Jun 2018 00:58:35 -0400 Received: from lgeamrelo13.lge.com ([156.147.23.53]:59053 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932585AbeFRE6b (ORCPT ); Mon, 18 Jun 2018 00:58:31 -0400 Received: from unknown (HELO lgeamrelo01.lge.com) (156.147.1.125) by 156.147.23.53 with ESMTP; 18 Jun 2018 13:58:29 +0900 X-Original-SENDERIP: 156.147.1.125 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO localhost.localdomain) (10.177.222.33) by 156.147.1.125 with ESMTP; 18 Jun 2018 13:58:27 +0900 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, joel@joelfernandes.org Subject: [RESEND PATCH v5 2/2] sched/deadline: Set cp->elements[0].cpu to -1 when the heap is empty Date: Mon, 18 Jun 2018 13:58:25 +0900 Message-Id: <1529297905-24703-2-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1529297905-24703-1-git-send-email-byungchul.park@lge.com> References: <1529297905-24703-1-git-send-email-byungchul.park@lge.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Steven and Daniel, I've changed the 2nd patch a little bit to consider cpudl_clear() additionally. Can I keep your Acked-by on? (I temporarily removed the Acked-by you gave me.) Acked-by: Steven Rostedt (VMware) Acked-by: Daniel Bristot de Oliveira -----8<----- >From 1e368d276186c22f9da298206c718b33e805828d Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Mon, 4 Jun 2018 15:05:08 +0900 Subject: [RESEND PATCH v5 2/2] sched/deadline: Set cp->elements[0].cpu to -1 when the heap is empty Currently, migrating tasks to cpu0 unconditionally happens when the heap is empty, since cp->elements[0].cpu is 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 the case the heap is empty. Signed-off-by: Byungchul Park Suggested-by: Joel Fernandes --- kernel/sched/cpudeadline.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index ae4fbdc..a200b36 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -136,6 +136,10 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); + /* The heap tree is empty, 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) @@ -172,6 +176,13 @@ void cpudl_clear(struct cpudl *cp, int cpu) * This could happen if a rq_offline_dl is * called for a CPU without -dl tasks running. */ + } else if (cp->size == 1){ + /* Only one element in the heap, clear it. */ + cp->elements[0].cpu = -1; + cp->elements[cpu].idx = IDX_INVALID; + cp->size = 0; + + cpumask_set_cpu(cpu, cp->free_cpus); } else { new_cpu = cp->elements[cp->size - 1].cpu; cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl; @@ -267,6 +278,9 @@ int cpudl_init(struct cpudl *cp) for_each_possible_cpu(i) cp->elements[i].idx = IDX_INVALID; + /* Mark heap as initially empty. */ + cp->elements[0].cpu = -1; + return 0; } -- 1.9.1