Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1037446AbdDUJjs (ORCPT ); Fri, 21 Apr 2017 05:39:48 -0400 Received: from foss.arm.com ([217.140.101.70]:35068 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1036601AbdDUJjP (ORCPT ); Fri, 21 Apr 2017 05:39:15 -0400 Date: Fri, 21 Apr 2017 10:39:26 +0100 From: Juri Lelli To: luca abeni Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Claudio Scordino , Steven Rostedt , Tommaso Cucinotta , Daniel Bristot de Oliveira , Mathieu Poirier Subject: Re: [PATCH] sched/deadline: fix switching to -deadline Message-ID: <20170421093926.GQ23862@e106622-lin> References: <1492716656-5362-1-git-send-email-luca.abeni@santannapisa.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1492716656-5362-1-git-send-email-luca.abeni@santannapisa.it> 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 Content-Length: 1618 Lines: 42 Hi Luca, On 20/04/17 21:30, Luca Abeni wrote: > From: Luca Abeni > > When switching to -deadline, if the scheduling deadline of a task is > in the past then switched_to_dl() calls setup_new_entity() to properly > initialize the scheduling deadline and runtime. > > The problem is that the task is enqueued _before_ having its parameters > initialized by setup_new_entity(), and this can cause problems. > For example, a task with its out-of-date deadline in the past will > potentially be enqueued as the highest priority one; however, its > adjusted deadline may not be the earliest one. > > This patch fixes the problem by initializing the task's parameters before > enqueuing it. > > Signed-off-by: Luca Abeni > Reviewed-by: Daniel Bristot de Oliveira > --- > kernel/sched/deadline.c | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index a2ce590..ec53d24 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -950,6 +950,10 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, > update_dl_entity(dl_se, pi_se); > else if (flags & ENQUEUE_REPLENISH) > replenish_dl_entity(dl_se, pi_se); > + else if ((flags & ENQUEUE_RESTORE) && Not sure I understand how this works. AFAICT we are doing __sched_setscheduler() when we want to catch the case of a new dl_entity (SCHED_{OTHER,FIFO} -> SCHED_DEADLINE}, but queue_flags (which are passed to enqueue_task()) don't seem to have ENQUEUE_RESTORE set? Thanks, - Juri