From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935905AbdEWCBo (ORCPT ); Mon, 22 May 2017 22:01:44 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:56822 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756585AbdEWCBh (ORCPT ); Mon, 22 May 2017 22:01:37 -0400 X-Original-SENDERIP: 156.147.1.125 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 165.244.249.26 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: , CC: , , , , Subject: [PATCH v5 4/4] sched/rt: Add support for SD_PREFER_SIBLING on find_lowest_rq() Date: Tue, 23 May 2017 11:00:59 +0900 Message-ID: <1495504859-10960-5-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1495504859-10960-1-git-send-email-byungchul.park@lge.com> References: <1495504859-10960-1-git-send-email-byungchul.park@lge.com> X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB01/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/05/23 11:01:17, Serialize by Router on LGEKRMHUB01/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/05/23 11:01:17, Serialize complete at 2017/05/23 11:01:17 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It would be better to avoid pushing tasks to other cpu within a SD_PREFER_SIBLING domain, instead, get more chances to check other siblings. Signed-off-by: Byungchul Park --- kernel/sched/rt.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 979b734..6332b2ad 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1624,6 +1624,7 @@ static int find_lowest_rq(struct task_struct *task) struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); int this_cpu = smp_processor_id(); int cpu = task_cpu(task); + int fallback_cpu = -1; /* Make sure the mask is initialized first */ if (unlikely(!lowest_mask)) @@ -1671,6 +1672,15 @@ static int find_lowest_rq(struct task_struct *task) best_cpu = cpumask_first_and(lowest_mask, sched_domain_span(sd)); if (best_cpu < nr_cpu_ids) { + /* + * If current domain is SD_PREFER_SIBLING + * flaged, we have to get more chances to + * check other siblings. + */ + if (sd->flags & SD_PREFER_SIBLING) { + fallback_cpu = best_cpu; + continue; + } rcu_read_unlock(); return best_cpu; } @@ -1679,6 +1689,13 @@ static int find_lowest_rq(struct task_struct *task) rcu_read_unlock(); /* + * If fallback_cpu is valid, all our quesses failed *except* for + * SD_PREFER_SIBLING domain. Now, we can return the fallback cpu. + */ + if (fallback_cpu != -1) + return fallback_cpu; + + /* * And finally, if there were no matches within the domains * just give the caller *something* to work with from the compatible * locations. -- 1.9.1