Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755948AbdLTUc2 (ORCPT ); Wed, 20 Dec 2017 15:32:28 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:34903 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754428AbdLTUc0 (ORCPT ); Wed, 20 Dec 2017 15:32:26 -0500 X-Google-Smtp-Source: ACJfBovvoVz9gQtELtivuBDXUFpLdggcWLxyrmT8PeyE/VQY09GqkU7onHVtASNEXuVFbMM/LAUZLH+qmdjDmd6XjaY= MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com From: "Michael Kerrisk (man-pages)" Date: Wed, 20 Dec 2017 21:32:04 +0100 Message-ID: Subject: Cgroups v2 thread mode "domain invalid" state To: Tejun Heo Cc: Peter Zijlstra , longman@redhat.com, lkml , Michael Kerrisk , linux-man , "open list:CONTROL GROUP (CGROUP)" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1056 Lines: 28 Hello Tejun, At some point, I'd like to add some details about cgroups v2 "thread mode" to the cgroup(7) manual page. I think I understand most of the details by now, but there's one question I still can't work out an answer to: why does the "domain invalid" cgroup type exist? I did find the July 2017 mail thread "[PATCH 5/6] cgroup: implement cgroup v2 thread support" (https://marc.info/?t=150025735500001&r=1&w=2) where this cgroup type was discussed, but I must admit that I still don't get it. Instead of converting cgroups under a threaded subtree to "domain invalid" type, why can't they just be turned straight into "threaded" type? I guess another way of asking this question is: what possibilities does manually switching each "domain invalid" cgroup to "threaded" allow that wouldn't be allowed by immediately making all of the cgroups in a threaded subtree "threaded"? Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/