From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755172AbcGEOjP (ORCPT ); Tue, 5 Jul 2016 10:39:15 -0400 Received: from foss.arm.com ([217.140.101.70]:53489 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752088AbcGEOjN (ORCPT ); Tue, 5 Jul 2016 10:39:13 -0400 Date: Tue, 5 Jul 2016 15:39:33 +0100 From: Juri Lelli To: Steven Rostedt Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, luca.abeni@unitn.it Subject: Re: [PATCH v2] sched/deadline: remove useless param from setup_new_dl_entity Message-ID: <20160705143933.GJ17689@e106622-lin> References: <1467227263-31349-1-git-send-email-juri.lelli@arm.com> <20160705102013.25a1a1dc@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160705102013.25a1a1dc@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/07/16 10:20, 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 && ^ OK, we need to reorder these two V > (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. > But, yes. Looks good to me. I'll shoot a v3 ASAP. Thanks, - Juri