Received: by 2002:a25:ad19:0:0:0:0:0 with SMTP id y25csp6552878ybi; Mon, 8 Jul 2019 04:57:18 -0700 (PDT) X-Google-Smtp-Source: APXvYqy7DibsydXE+dURhWIPH37sCgD3GnG/WEFXPhwr5tIkJRiaZaIemJs3Or7FRnQU/m7z4J0O X-Received: by 2002:a63:1918:: with SMTP id z24mr20164622pgl.94.1562587038721; Mon, 08 Jul 2019 04:57:18 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1562587038; cv=none; d=google.com; s=arc-20160816; b=OUTmnvvv0cxMfTPQnBk8/khAoV1PL4w7BIevQ/vvVJsF+iWWH6eKgrC4BRFndZoAMu stThadkzdjWBRd0j/+mOU1vHD7c9nw1dPLCvpa+78MR8tE+mJw9bI5CadJEpbIaSs3EN Q+zxDlsrf7QK5H8MFpJe/86Tx4qC1vIWF30SKUcDvdaK62a7h/aGOIZpzwgj+JSOSGH2 2estGVZ+w0LUJuCc5iYvLjkAqmvu0B0jTfFNx9SJCzgOfqYL5DKN0J80ll1h/N0KQk+5 9gcfmecTTKRuNHP5aCs9ijUw4hFIt99Y5FeeVgN+UzsEwJG1vjtFfPTavavXYwApgN8L TuOA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:subject:cc:to:from:date; bh=jFYUxWiN8HVyh5ELvck8ANbA0jIQflKbvaVEydga3Zk=; b=evhARLtjxFK/dQv1jrAFyJEo+0oM3ADqrywpCGa/ZybqE1nl2lkecnMgRJaHjAJ4Qf v1CNuTN3ruzlZxtYuKHFmGJyo9XKy7KcizljmontpdQtgfqL5DmIlMe/HVI55Ji5zUcR Fyfxcjf76IECF5rLuRxlUEqTKaKO7oLHXgRqb6+KK3iQXIZV6TF24ikUqiINjjBiI6d8 WV+HUPl+q53VQWpxHzsutfLhFwn8hBcgQ3cYfaHpF9YeoMR2hsiQY+yQnF7z/58yonNU qExo4THaFQmjNj0fe0RDnzHcxEb2V9nHfTJGIyQtRGQXX8cZbO73W9PQuezUYe9yyDSM Wwpw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id s9si11025033plr.146.2019.07.08.04.57.03; Mon, 08 Jul 2019 04:57:18 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728603AbfGHIls (ORCPT + 99 others); Mon, 8 Jul 2019 04:41:48 -0400 Received: from mail.santannapisa.it ([193.205.80.98]:30743 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727976AbfGHIls (ORCPT ); Mon, 8 Jul 2019 04:41:48 -0400 X-Greylist: delayed 3600 seconds by postgrey-1.27 at vger.kernel.org; Mon, 08 Jul 2019 04:41:46 EDT Received: from [151.41.66.174] (account l.abeni@santannapisa.it HELO sweethome) by santannapisa.it (CommuniGate Pro SMTP 6.1.11) with ESMTPSA id 140626216; Mon, 08 Jul 2019 09:41:44 +0200 Date: Mon, 8 Jul 2019 09:41:36 +0200 From: luca abeni To: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , "Rafael J . Wysocki" , Ingo Molnar , Peter Zijlstra , Vincent Guittot , "Paul E . McKenney" , Joel Fernandes , Quentin Perret , Luc Van Oostenryck , Morten Rasmussen , Juri Lelli , Daniel Bristot de Oliveira , Patrick Bellasi , Tommaso Cucinotta Subject: Re: [RFC PATCH 2/6] sched/dl: Capacity-aware migrations Message-ID: <20190708094136.7bce5f46@sweethome> In-Reply-To: References: <20190506044836.2914-1-luca.abeni@santannapisa.it> <20190506044836.2914-3-luca.abeni@santannapisa.it> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dietmar, On Thu, 4 Jul 2019 14:05:22 +0200 Dietmar Eggemann wrote: > On 5/6/19 6:48 AM, Luca Abeni wrote: > > [...] > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > index 5b981eeeb944..3436f3d8fa8f 100644 > > --- a/kernel/sched/deadline.c > > +++ b/kernel/sched/deadline.c > > @@ -1584,6 +1584,9 @@ select_task_rq_dl(struct task_struct *p, int > > cpu, int sd_flag, int flags) if (sd_flag != SD_BALANCE_WAKE) > > goto out; > > > > + if (dl_entity_is_special(&p->dl)) > > + goto out; > > I wonder if this is really required. The if condition > > 1591 if (unlikely(dl_task(curr)) && > 1592 (curr->nr_cpus_allowed < 2 || > 1593 !dl_entity_preempt(&p->dl, &curr->dl)) && > 1594 (p->nr_cpus_allowed > 1)) { > > further below uses '!dl_entity_preempt(&p->dl, &curr->dl))' which > returns 'dl_entity_is_special(a) || ...' Uhm... I do not remember the details; I remember that the check fixed something during the development of the patchset, but I did not check if it was still needed when I forward-ported the patches... So, maybe it worked around some bugs in previous versions of the kernel, but is not needed now. Luca