From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752143AbeBBOSN (ORCPT ); Fri, 2 Feb 2018 09:18:13 -0500 Received: from mail.sssup.it ([193.205.80.99]:19199 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469AbeBBOSG (ORCPT ); Fri, 2 Feb 2018 09:18:06 -0500 Date: Fri, 2 Feb 2018 14:17:50 +0100 From: Luca Abeni To: Mathieu Poirier Cc: peterz@infradead.org, lizefan@huawei.com, mingo@redhat.com, rostedt@goodmis.org, claudio@evidence.eu.com, bristot@redhat.com, tommaso.cucinotta@santannapisa.it, juri.lelli@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 0/7] sched/deadline: fix cpusets bandwidth accounting Message-ID: <20180202141750.5652d2b7@luca> In-Reply-To: <1517503869-3179-1-git-send-email-mathieu.poirier@linaro.org> References: <1517503869-3179-1-git-send-email-mathieu.poirier@linaro.org> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; 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 Mathieu, On Thu, 1 Feb 2018 09:51:02 -0700 Mathieu Poirier wrote: > This is the follow-up patchset to [1] that attempt to fix a problem > reported by Steve Rostedt [2] where DL bandwidth accounting is not > recomputed after CPUset and CPU hotplug operations. When CPU hotplug and > some CUPset manipulation take place root domains are destroyed and new ones > created, loosing at the same time DL accounting information pertaining to > utilisation. Please see [1] for a full description of the approach. I do not know the cgroup / cpuset code too much, so I have no useful comments on your patches... But I think this patchset is a nice improvemnt respect to the current situation. [...] > A notable addition is patch 7/7 - it addresses a problem seen when hot > plugging out a CPU where a DL task is running (see changelog for full > details). The issue is unrelated to this patchset and will manifest > itself on a mainline kernel. I think I introduced this bug with my reclaiming patches, so I am interested. When a cpu is hot-plugged out, which code in the kernel is responsible for migrating the tasks that are executing on such CPU? I was sure I was handling all the relevant codepaths, but this bug clearly shows that I was wrong. Thanks, Luca