From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juri Lelli Subject: Re: [PATCH v9 4/8] sched/deadline: Fix bandwidth accounting at all levels after offline migration Date: Mon, 22 Jul 2019 14:28:28 +0200 Message-ID: <20190722122828.GG25636@localhost.localdomain> References: <20190719140000.31694-1-juri.lelli@redhat.com> <20190719140000.31694-5-juri.lelli@redhat.com> <5da6abab-00ff-9bb4-f24b-0bf5dfcd4c35@arm.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <5da6abab-00ff-9bb4-f24b-0bf5dfcd4c35@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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. Thanks, Juri