From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6766C76188 for ; Mon, 22 Jul 2019 13:35:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B44D621921 for ; Mon, 22 Jul 2019 13:35:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729532AbfGVNf0 (ORCPT ); Mon, 22 Jul 2019 09:35:26 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:33242 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725989AbfGVNf0 (ORCPT ); Mon, 22 Jul 2019 09:35:26 -0400 Received: by mail-wr1-f66.google.com with SMTP id n9so39527822wru.0 for ; Mon, 22 Jul 2019 06:35:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=EuDatz2cIPnBgSI+pkeWKDYDKyeOHk8JclCsQ5sZzLM=; b=W2OKURJClLrDk7s6t0JgiUDG5uI+76YZQ16oApK7L8HeC9b5o/XeQtzCIe7AqhRJf4 Cjcq44w74iVqRJ/POA7BEq4O3qje8A395SWXSXDHwFqOTX0teq7PsXXUYGgVbtUy5gQy qTqh4mmF7ntwhiG5r598TiEiizR9nvjfpDzYdCy3cG8RbU2nguaU2akxNGaOAcA0sQzN JPDMJEnMIJk1G3R/VAD+tOOQej7SrohokhrpNs2GebGQw+uOth25iBN9NaWQM3yq02Wa ByjGgGhyU8djk3u1nj/1OuWfipVwtPnjWLkPwbkAp9R7LkDVUMgCddcC7hVjXHFQUshp zF3w== X-Gm-Message-State: APjAAAVKWSCTK097aGjPYBVflgaulLTBckkExQJXI57PElYLYIofE3zY w9ZWo1T93sVGFRE0IkieWp79Wg== X-Google-Smtp-Source: APXvYqzstqSW3XoFfkCp9xxLOQKWJdHWzx1oDl6TMekdXwTGBVSAn5QVX8ZB6ardIoyNMSeKcj+hdQ== X-Received: by 2002:adf:df10:: with SMTP id y16mr51366719wrl.302.1563802523990; Mon, 22 Jul 2019 06:35:23 -0700 (PDT) Received: from localhost.localdomain ([151.15.230.231]) by smtp.gmail.com with ESMTPSA id f2sm32641570wrq.48.2019.07.22.06.35.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Jul 2019 06:35:22 -0700 (PDT) Date: Mon, 22 Jul 2019 15:35:20 +0200 From: Juri Lelli To: Dietmar Eggemann Cc: peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, tj@kernel.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, bristot@redhat.com, mathieu.poirier@linaro.org, lizefan@huawei.com, longman@redhat.com, cgroups@vger.kernel.org Subject: Re: [PATCH v9 4/8] sched/deadline: Fix bandwidth accounting at all levels after offline migration Message-ID: <20190722133520.GH25636@localhost.localdomain> References: <20190719140000.31694-1-juri.lelli@redhat.com> <20190719140000.31694-5-juri.lelli@redhat.com> <5da6abab-00ff-9bb4-f24b-0bf5dfcd4c35@arm.com> <20190722122828.GG25636@localhost.localdomain> <07a45864-07bf-aa5d-3ff7-a300326b9040@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <07a45864-07bf-aa5d-3ff7-a300326b9040@arm.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/07/19 15:21, Dietmar Eggemann wrote: > On 7/22/19 2:28 PM, Juri Lelli wrote: > > On 22/07/19 13:07, Dietmar Eggemann wrote: > >> On 7/19/19 3:59 PM, Juri Lelli wrote: > >> > >> [...] > >> > >>> @@ -557,6 +558,38 @@ static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p > >>> double_lock_balance(rq, later_rq); > >>> } > >>> > >>> + if (p->dl.dl_non_contending || p->dl.dl_throttled) { > >>> + /* > >>> + * Inactive timer is armed (or callback is running, but > >>> + * waiting for us to release rq locks). In any case, when it > >>> + * will file (or continue), it will see running_bw of this > >> > >> s/file/fire ? > > > > Yep. > > > >>> + * task migrated to later_rq (and correctly handle it). > >> > >> Is this because of dl_task_timer()->enqueue_task_dl()->task_contending() > >> setting dl_se->dl_non_contending = 0 ? > > > > No, this is related to inactive_task_timer() callback. Since the task is > > migrated (by this function calling set_task_cpu()) because a CPU hotplug > > operation happened, we need to reflect this w.r.t. running_bw, or > > inactive_task_timer() might sub from the new CPU and cause running_bw to > > underflow. > > I was more referring to the '... it will see running_bw of thus task > migrated to later_rq ...) and specifically to the HOW the timer > callback can detect this. Oh, it actually doesn't "actively" detect this condition. The problem is that if it still sees dl_non_contending == 1, it will sub (from the "new" rq to which task's running_bw hasn't been added - w/o this fix) and cause the underflow.