Message-ID: <552E7A3B.3060803@redhat.com>
Date: Wed, 15 Apr 2015 16:48:27 +0200
From: Michal Schmidt <mschmidt@redhat.com>
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To: Mike Galbraith <umgwanakikbuti@gmail.com>
CC: Richard Weinberger <richard.weinberger@gmail.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Tom Gundersen <teg@jklm.no>, Jiri Kosina <jkosina@suse.cz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Daniel Mack <daniel@zonque.org>,
        David Herrmann <dh.herrmann@gmail.com>,
        Djalal Harouni <tixxdz@opendz.org>
Subject: Re: [GIT PULL] kdbus for 4.1-rc1
References: <20150413190350.GA9485@kroah.com>	 <8738434yjk.fsf@x220.int.ebiederm.org> <20150413194217.GA10837@kroah.com>	 <20150413202233.GR889@ZenIV.linux.org.uk>	 <CALCETrUEAxFqwU4beeXYpdyRAO6yDRSNvcBqhvpMVORy00ySgg@mail.gmail.com>	 <CAFLxGvz9sn7rk1zU5tA8wPtn0T6ujR_tmEhLQeBcVOtKL00wdA@mail.gmail.com> <1429083093.3508.21.camel@gmail.com>
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On 04/15/2015 09:31 AM, Mike Galbraith wrote:
> it seems [systemd] has now mandated group scheduling.

What makes you think so? Was it the fact that by default you have a
populated /sys/fs/cgroup/cpu/ hierarchy? This is either because some
unit requests the use of the cpu controller using one of the CPU*=
directives from systemd.resource-control(5), or (perhaps more likely)
because there is a privileged unit with Delegate=yes. The most likely
candidate is user@0.service, and so you could try preventing it from
starting:
  systemctl mask user@0.service

Note that systemd still works without group scheduling or any cgroup
subsystems enabled in the kernel:

  $ grep GROUP .config
  CONFIG_CGROUPS=y
  # CONFIG_CGROUP_DEBUG is not set
  # CONFIG_CGROUP_FREEZER is not set
  # CONFIG_CGROUP_DEVICE is not set
  # CONFIG_CGROUP_CPUACCT is not set
  # CONFIG_CGROUP_HUGETLB is not set
  # CONFIG_CGROUP_PERF is not set
  # CONFIG_CGROUP_SCHED is not set
  # CONFIG_BLK_CGROUP is not set
  # CONFIG_SCHED_AUTOGROUP is not set
  # CONFIG_NETFILTER_XT_MATCH_CGROUP is not set
  # CONFIG_NETFILTER_XT_MATCH_DEVGROUP is not set
  # CONFIG_NET_CLS_CGROUP is not set
  # CONFIG_CGROUP_NET_PRIO is not set
  # CONFIG_CGROUP_NET_CLASSID is not set

Michal
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