Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752422AbbEDDOG (ORCPT ); Sun, 3 May 2015 23:14:06 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:36668 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbbEDDNz (ORCPT ); Sun, 3 May 2015 23:13:55 -0400 Message-ID: <1430709236.3129.42.camel@gmail.com> Subject: Re: [PATCH] sched: Relax a restriction in sched_rt_can_attach() From: Mike Galbraith To: Zefan Li Cc: Ingo Molnar , Peter Zijlstra , Tejun Heo , LKML , Cgroups Date: Mon, 04 May 2015 05:13:56 +0200 In-Reply-To: <5546C34C.7050202@huawei.com> References: <5546C34C.7050202@huawei.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1098 Lines: 25 On Mon, 2015-05-04 at 08:54 +0800, Zefan Li wrote: > It's allowed to promote a task from normal to realtime after it has been > attached to a non-root cgroup, but it will fail if the attaching happens > after it has become realtime. I don't see how this restriction is useful. In the CONFIG_RT_GROUP_SCHED case, promotion will fail is there is no bandwidth allocated. > We are moving toward unified hierarchy where all the cgroup controllers > are bound together, so it would make cgroups easier to use if we have less > restrictions on attaching tasks between cgroups. Forcing group scheduling overhead on users if they want cpuset or memory cgroup functionality would be far from wonderful. Am I interpreting the implications of this unification/binding properly? (I hope not, surely the plan is not to utterly _destroy_ cgroup utility) -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/