Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1037898AbdDUK0u (ORCPT ); Fri, 21 Apr 2017 06:26:50 -0400 Received: from foss.arm.com ([217.140.101.70]:35448 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1037861AbdDUK0r (ORCPT ); Fri, 21 Apr 2017 06:26:47 -0400 Date: Fri, 21 Apr 2017 11:26:59 +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: <20170421102659.GS23862@e106622-lin> References: <1492716656-5362-1-git-send-email-luca.abeni@santannapisa.it> <20170421093926.GQ23862@e106622-lin> <20170421114240.0ef43522@nowhere> <20170421094729.GR23862@e106622-lin> <20170421115907.4044665a@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170421115907.4044665a@nowhere> 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: 1212 Lines: 31 On 21/04/17 11:59, Luca Abeni wrote: > On Fri, 21 Apr 2017 10:47:29 +0100 > Juri Lelli wrote: > [...] > > > > > *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... > > > > Oh, I think it works "by coincidence", as ENQUEUE_RESTORE == > > DEQUEUE_SAVE == 0x02 ? :) > > Not sure if this is a conincidence... By looking at the comments in > sched/sched.h I got the impression the two values match by design (and > __sched_setscheduler() is using this property to simplify the code :) > Yep, right. Do you think we might get into trouble with do_set_cpus_allowed()? Can it happen that we change a task affinity while its deadline is in the past?