From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751156AbdBWDTQ (ORCPT ); Wed, 22 Feb 2017 22:19:16 -0500 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:42544 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955AbdBWDTO (ORCPT ); Wed, 22 Feb 2017 22:19:14 -0500 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.185 X-Original-MAILFROM: byungchul.park@lge.com From: "byungchul.park" To: , Cc: , , , References: <1487819438-3364-1-git-send-email-byungchul.park@lge.com> <1487819438-3364-2-git-send-email-byungchul.park@lge.com> In-Reply-To: <1487819438-3364-2-git-send-email-byungchul.park@lge.com> Subject: RE: [PATCH v2 2/2] sched/deadline: Change the way to replenish runtime for sleep tasks Date: Thu, 23 Feb 2017 12:18:48 +0900 Message-ID: <008a01d28d83$8d0605a0$a71210e0$@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQHUSEMAgsvym9ibYR7Hq+vMA8xxIwE1Rfg3oWjLUIA= Content-Language: ko Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Byungchul Park [mailto:byungchul.park@lge.com] > Sent: Thursday, February 23, 2017 12:11 PM > To: peterz@infradead.org; mingo@kernel.org > Cc: linux-kernel@vger.kernel.org; juri.lelli@gmail.com; > rostedt@goodmis.org; kernel-team@lge.com > Subject: [PATCH v2 2/2] sched/deadline: Change the way to replenish > runtime for sleep tasks > > Let's consider the following example. > > timeline : o...................o.........o.......o..o > ^ ^ ^ ^ ^ > | | | | | > start | | | | > original runtime | | | > sleep with (-)runtime | | > original deadline | > wake up > > When this task is woken up, a negative runtime should be considered, > which means that the task should get penalized when assigning runtime, > becasue it already spent more than expected. > > Current code handles this by replenishing a runtime in hrtimer callback > for deadline. But this approach has room for improvement in two ways: > > 1. No need to keep the hrtimer for a sleep task because it can be > handled when waking it up. > > 2. It will be replenished twice unnecessarily if the task sleeps for > long time so that the deadline, assigned in the hrtimer callback, > also passed. In other words, one happens in the callback and the > other happens in update_dl_entiry() when waking it up. > > So try to cancel the hrtimer for a sleep task and make all these things > handled when waking it up. > > Signed-off-by: Byungchul Park > --- > kernel/sched/deadline.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 69e3fbb..b59ee7b 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -507,8 +507,10 @@ static void update_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); > > - if (dl_time_before(dl_se->deadline, rq_clock(rq)) || > - dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { > + if (dl_time_before(dl_se->deadline, rq_clock(rq))) > + __replenish_dl_entity(dl_se, pi_se); > + > + if (dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { > dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; > dl_se->runtime = pi_se->dl_runtime; > } > @@ -981,6 +983,9 @@ static void dequeue_task_dl(struct rq *rq, struct > task_struct *p, int flags) > { > update_curr_dl(rq); > __dequeue_task_dl(rq, p, flags); > + > + if (flags & DEQUEUE_SLEEP) > + hrtimer_try_to_cancel(&p->dl.dl_timer); Sorry. I found I might have made a mistake. I might have to re-start the timer when waking it up if necessary. Let me think more. > } > > /* > -- > 1.9.1