From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752798AbcBKMXF (ORCPT ); Thu, 11 Feb 2016 07:23:05 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:35681 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751607AbcBKMXD (ORCPT ); Thu, 11 Feb 2016 07:23:03 -0500 Date: Thu, 11 Feb 2016 13:22:54 +0100 From: luca abeni To: Juri Lelli Cc: Steven Rostedt , linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, wanpeng.li@hotmail.com Subject: Re: [PATCH 1/2] sched/deadline: add per rq tracking of admitted bandwidth Message-ID: <20160211132254.1a369fe9@utopia> In-Reply-To: <20160211121257.GL11415@e106622-lin> References: <1454935531-7541-1-git-send-email-juri.lelli@arm.com> <1454935531-7541-2-git-send-email-juri.lelli@arm.com> <20160210113258.GX11415@e106622-lin> <20160210093702.10c655be@gandalf.local.home> <20160210162748.GI11415@e106622-lin> <20160211121257.GL11415@e106622-lin> Organization: university of trento X-Mailer: Claws Mail 3.12.0 (GTK+ 2.24.28; 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 Hi Juri, On Thu, 11 Feb 2016 12:12:57 +0000 Juri Lelli wrote: [...] > I think we still have (at least) two problems: > > - select_task_rq_dl, if we select a different target > - select_task_rq might make use of select_fallback_rq, if > cpus_allowed changed after the task went to sleep > > Second case is what creates the problem here, as we don't update > task_rq(p) and fallback_cpu ac_bw. I was thinking we might do so, > maybe adding fallback_cpu in task_struct, from migrate_task_rq_dl() > (it has to be added yes), but I fear that we should hold both rq > locks :/. > > Luca, did you already face this problem (if I got it right) and > thought of a way to fix it? I'll go back and stare a bit more at > those paths. In my patch I took care of the first case (modifying select_task_rq_dl() to move the utilization from the "old rq" to the "new rq"), but I never managed to trigger select_fallback_rq() in my tests, so I overlooked that case. Luca