[RFD] cgroup: about multiple hierarchies

[Mike Galbraith]

On Mon, 2012-03-05 at 13:43 +0100, Lennart Poettering wrote: 
> On Thu, 01.03.12 23:04, Mike Galbraith (efault at gmx.de) wrote:
> 
> > 
> > On Thu, 2012-03-01 at 16:02 -0500, Vivek Goyal wrote: 
> > > On Thu, Mar 01, 2012 at 09:26:43PM +0100, Mike Galbraith wrote:
> > 
> > > > Q: you say systemd requires CONFIG_CGROUPS=y.  Why is that?  It's taking
> > > > over sysvinits job afaiui, what does that have to do with cgroups?
> > > 
> > > I think they were using it to track all the children forked by a service
> > > and cleanup all of them if need be. So they just need it for logical
> > > grouping functionality and don't require any controllers as such.
> > 
> > Hm.  Controllers are perhaps not required, but cpu controller was
> > configured and used without consent.  I didn't receive an offer.
> 
> Just set DefaultControllers= in /etc/systemd/system.conf to an empty
> string and systemd will not make use of any hierarchy beyond its private
> name=systemd named hierarchy.

I updated my laptop to openSUSE 12.1 over the weekend, so tried it.  It
didn't work, so I tried setting JoinControllers= as well.  That split up
cpu and cpuacct, but didn't stop cpu from being used.  I then moved both
system.conf and user.conf to /etc/systemd/save, and got the original
setup back.. not surprising given everything was commented out in both
files to begin with.  The little bugger is stubborn.

maggy:/etc/systemd # mount|grep cgroup
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,relatime,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/ns type cgroup (rw,nosuid,nodev,noexec,relatime,ns)
cgroup on /sys/fs/cgroup/cpu type cgroup (rw,nosuid,nodev,noexec,relatime,cpu)
cgroup on /sys/fs/cgroup/cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
maggy:/etc/systemd # cat /sys/fs/cgroup/cpu/tasks|wc -l
262
maggy:/etc/systemd # cat system.conf
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
# See systemd.conf(5) for details

[Manager]
#LogLevel=info
#LogTarget=syslog-or-kmsg
#LogColor=yes
#LogLocation=no
#DumpCore=yes
#CrashShell=no
#ShowStatus=yes
#SysVConsole=yes
#CrashChVT=1
#CPUAffinity=1 2
#MountAuto=yes
#SwapAuto=yes
DefaultControllers=
#DefaultStandardOutput=syslog
#DefaultStandardError=inherit
JoinControllers=
maggy:/etc/systemd #

reboot...

maggy:/etc/systemd # mount|grep cgroup
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,relatime,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/ns type cgroup (rw,nosuid,nodev,noexec,relatime,ns)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
maggy:/etc/systemd # cat /sys/fs/cgroup/cpu/tasks|wc -l
146
maggy:/etc/systemd # ls
save  system  systemd-logind.conf  user
maggy:/etc/systemd #