From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752709AbdBPCGX (ORCPT ); Wed, 15 Feb 2017 21:06:23 -0500 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:41896 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745AbdBPCGU (ORCPT ); Wed, 15 Feb 2017 21:06:20 -0500 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 165.244.249.23 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 v2 1/2] sched/deadline: Remove unnecessary condition in push_dl_task() Date: Thu, 16 Feb 2017 11:05:53 +0900 Message-ID: <1487210754-17252-1-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB03/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/02/16 11:06:16, Serialize by Router on LGEKRMHUB03/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/02/16 11:06:16, Serialize complete at 2017/02/16 11:06:16 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 Once pick_next_pushable_dl_task(rq) returns a task, it guarantees that the task's cpu is rq->cpu, so task_cpu(next_task) is always rq->cpu if task == next_task. Remove the redundant condition and make code simpler. pick_next_pushable_dl_task(rq) has BUG_ON(rq->cpu != task_cpu(task)) when it returns a task other than NULL, which means that task_cpu(task) must be rq->cpu. So if task == next_task, then task_cpu(next_task) must be rq->cpu as well. By this patch, unnecessary one branch and two LOAD operations in 'if' statement can be avoided. Signed-off-by: Byungchul Park --- kernel/sched/deadline.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 27737f3..ad8d577 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1483,7 +1483,7 @@ static int push_dl_task(struct rq *rq) * then possible that next_task has migrated. */ task = pick_next_pushable_dl_task(rq); - if (task_cpu(next_task) == rq->cpu && task == next_task) { + if (task == next_task) { /* * The task is still there. We don't try * again, some other cpu will pull it when ready. -- 1.9.1