Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1037444AbdDUJnl (ORCPT ); Fri, 21 Apr 2017 05:43:41 -0400 Received: from mail.santannapisa.it ([193.205.80.98]:28932 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S971117AbdDUJmr (ORCPT ); Fri, 21 Apr 2017 05:42:47 -0400 Date: Fri, 21 Apr 2017 11:42:40 +0200 From: luca abeni To: Juri Lelli 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: <20170421114240.0ef43522@nowhere> In-Reply-To: <20170421093926.GQ23862@e106622-lin> References: <1492716656-5362-1-git-send-email-luca.abeni@santannapisa.it> <20170421093926.GQ23862@e106622-lin> Organization: Scuola Superiore S.Anna 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 Content-Length: 1837 Lines: 47 On Fri, 21 Apr 2017 10:39:26 +0100 Juri Lelli wrote: > 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 For example, a task with its out-of-date deadline in the 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? I was under the impression sched_setscheduler() sets ENQUEUE_RESTORE... Luca