From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753492AbcGFIqi (ORCPT ); Wed, 6 Jul 2016 04:46:38 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:36814 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752525AbcGFIqe (ORCPT ); Wed, 6 Jul 2016 04:46:34 -0400 Date: Wed, 6 Jul 2016 10:46:28 +0200 From: luca abeni To: Steven Rostedt Cc: Juri Lelli , peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [PATCH v2] sched/deadline: remove useless param from setup_new_dl_entity Message-ID: <20160706104628.4b17cffc@utopia> In-Reply-To: <20160705102013.25a1a1dc@gandalf.local.home> References: <1467227263-31349-1-git-send-email-juri.lelli@arm.com> <20160705102013.25a1a1dc@gandalf.local.home> Organization: university of trento X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 Jul 2016 10:20:13 -0400 Steven Rostedt wrote: > On Wed, 29 Jun 2016 20:07:43 +0100 > Juri Lelli wrote: > > > > --- > > kernel/sched/deadline.c | 14 +++++++++++--- > > 1 file changed, 11 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > index fcb7f0217ff4..2000ad2294d5 100644 > > --- a/kernel/sched/deadline.c > > +++ b/kernel/sched/deadline.c > > @@ -346,11 +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); > > + struct task_struct *pi_task = > > rt_mutex_get_top_task(dl_task_of(dl_se)); > > + struct sched_dl_entity *pi_se = dl_se; > > > > WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); > > > > @@ -363,6 +364,13 @@ static inline void setup_new_dl_entity(struct > > sched_dl_entity *dl_se, return; > > > > /* > > + * Use the scheduling parameters of the top pi-waiter task, > > + * if we have one from which we can inherit a deadline. > > + */ > > + if (pi_task && dl_se->dl_boosted && > > dl_prio(pi_task->normal_prio)) > > + pi_se = &pi_task->dl; > > + > > OK, I'm micro-optimizing now, but hey, isn't this a fast path? > > What about changing the above to: > > struct task_struct *pi_task; > [...] > > if (dl_se->dl_boosted && dl_prio(pi_task->normal_prio && > (pi_task = rt_mutex_get_top_task(dl_task_of(dl_se))) > pe_se = &pi_task->dl; > > This way we don't need to do any work of looking at > rt_mutex_get_top_task() for the normal case. If something like this is done, I think that enqueue_task_dl() (that contains similar code) should be updated too. Thanks, Luca > > -- Steve > > > > + /* > > * We use the regular wall clock time to set deadlines in > > the > > * future; in fact, we must consider execution overheads > > (time > > * spent on hardirq context, etc.). > > @@ -1721,7 +1729,7 @@ 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 (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) { > > #ifdef CONFIG_SMP >