From patchwork Fri Aug 5 15:07:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juri Lelli X-Patchwork-Id: 73362 Delivered-To: patch@linaro.org Received: by 10.140.29.52 with SMTP id a49csp1986036qga; Fri, 5 Aug 2016 08:07:57 -0700 (PDT) X-Received: by 10.66.161.225 with SMTP id xv1mr135392716pab.20.1470409677400; Fri, 05 Aug 2016 08:07:57 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id a16si20890941pfj.8.2016.08.05.08.07.57; Fri, 05 Aug 2016 08:07:57 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759923AbcHEPHy (ORCPT + 27 others); Fri, 5 Aug 2016 11:07:54 -0400 Received: from foss.arm.com ([217.140.101.70]:56987 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759865AbcHEPHx (ORCPT ); Fri, 5 Aug 2016 11:07:53 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BBE5528; Fri, 5 Aug 2016 08:09:16 -0700 (PDT) Received: from e106622-lin.cambridge.arm.com (e106622-lin.cambridge.arm.com [10.1.211.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D2A363F215; Fri, 5 Aug 2016 08:07:51 -0700 (PDT) From: Juri Lelli To: peterz@infradead.org Cc: rostedt@goodmis.org, linux-kernel@vger.kernel.org, mingo@redhat.com, luca.abeni@unitn.it, juri.lelli@arm.com, xpang@redhat.com Subject: [PATCH v6] sched/deadline: remove useless param from setup_new_dl_entity Date: Fri, 5 Aug 2016 16:07:55 +0100 Message-Id: <1470409675-20935-1-git-send-email-juri.lelli@arm.com> X-Mailer: git-send-email 2.7.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org setup_new_dl_entity() takes two parameters, but it only actually uses one of them, under a different name, to setup a new dl_entity, after: 2f9f3fdc928 "sched/deadline: Remove dl_new from struct sched_dl_entity" as we currently do setup_new_dl_entity(&p->dl, &p->dl) However, before Luca's change we were doing setup_new_dl_entity(dl_se, pi_se) in update_dl_entity() for a dl_se->new entity: we were using pi_se's parameters (the potential PI donor) for setting up a new entity. This change removes the useless second parameter of setup_new_dl_entity(). While we are at it we also optimize things further calling setup_new_dl_ entity() only for already queued tasks, since (as pointed out by Xunlei) we already do the very same update at tasks wakeup time anyway. By doing so, we don't need to worry about a potential PI donor anymore, as rt_ mutex_setprio() takes care of that already for us. Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Luca Abeni Cc: Xunlei Pang Signed-off-by: Juri Lelli Reviewed-by: Steven Rostedt --- Changes from v5: - simply return if task is not enqueued; improves readability and reduces indentation Changes from v4: - remove dead code checking for boosted status, as never triggered after rt_mutex_setprio() Changes from v3: - call setup_new_dl_entity only if task is enqueued already Changes from v2: - optimize by calling rt_mutex_get_top_task only if the task is boosted (as suggested by Steve) Changes from v1: - Steve pointed out that we were actually using the second parameter to permorm initialization - Luca confirmed that behavior is slightly changed w.r.t. before his change - changelog updated and original behavior restored --- kernel/sched/deadline.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) -- 2.7.0 diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index fcb7f0217ff4..03f35f66cf1f 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -346,12 +346,12 @@ static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, * one, and to (try to!) reconcile itself with its own scheduling * parameters. */ -static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se, - struct sched_dl_entity *pi_se) +static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); + WARN_ON(dl_se->dl_boosted); WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); /* @@ -367,8 +367,8 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se, * future; in fact, we must consider execution overheads (time * spent on hardirq context, etc.). */ - dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; - dl_se->runtime = pi_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; + dl_se->runtime = dl_se->dl_runtime; } /* @@ -1720,10 +1720,20 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p) */ static void switched_to_dl(struct rq *rq, struct task_struct *p) { + + /* If p is not queued we will update its parameters at next wakeup. */ + if (!task_on_rq_queued(p)) + return; + + /* + * If p is boosted we already updated its params in + * rt_mutex_setprio()->enqueue_task(..., ENQUEUE_REPLENISH), + * p's deadline being now already after rq_clock(rq). + */ if (dl_time_before(p->dl.deadline, rq_clock(rq))) - setup_new_dl_entity(&p->dl, &p->dl); + setup_new_dl_entity(&p->dl); - if (task_on_rq_queued(p) && rq->curr != p) { + if (rq->curr != p) { #ifdef CONFIG_SMP if (tsk_nr_cpus_allowed(p) > 1 && rq->dl.overloaded) queue_push_tasks(rq);