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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 149B2C31E49 for ; Wed, 19 Jun 2019 09:29:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7745206E0 for ; Wed, 19 Jun 2019 09:29:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731467AbfFSJ3J (ORCPT ); Wed, 19 Jun 2019 05:29:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:36960 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731267AbfFSJ3J (ORCPT ); Wed, 19 Jun 2019 05:29:09 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 28762ADCF; Wed, 19 Jun 2019 09:29:07 +0000 (UTC) Date: Wed, 19 Jun 2019 11:29:05 +0200 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: Juri Lelli Cc: peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, lizefan@huawei.com, tj@kernel.org, bristot@redhat.com, luca.abeni@santannapisa.it, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/core: Fix cpu controller for !RT_GROUP_SCHED Message-ID: <20190619092904.GB28937@blackbody.suse.cz> References: <20190605114935.7683-1-juri.lelli@redhat.com> <20190605142003.GD4255@blackbody.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190605142003.GD4255@blackbody.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 05, 2019 at 04:20:03PM +0200, Michal Koutný wrote: > I considered relaxing the check to non-root cgroups only, however, as > your example shows, it doesn't prevent reaching the avoided state by > other paths. I'm not that familiar with RT sched to tell whether > RT-priority tasks in different task_groups break any assumptions. So I had another look and the check is bogus. The RT sched with !CONFIG_RT_GROUP_SCHED works only with the struct rt_rq embedded in the generic struct rq -- regardless of the task's membership in the cpu controller hierarchy. Perhaps, the commit message may mention this also prevents enabling cpu controller on unified hierarchy (if there are any (kernel) RT tasks to migrate). Reviewed-by: Michal Koutný