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Subject: Re: [RFC/RFT PATCH v3] sched: automated per tty task groups
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Lennart Poettering <mzxreary@0pointer.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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Date: Wed, 17 Nov 2010 23:52:17 +0100
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On Wed, 2010-11-17 at 23:45 +0100, Lennart Poettering wrote:
> On Wed, 17.11.10 23:37, Peter Zijlstra (a.p.zijlstra@chello.nl) wrote:
> 
> > 
> > On Wed, 2010-11-17 at 23:34 +0100, Lennart Poettering wrote:
> > > 
> > > This should fix things for people with systemd and GNOME. Yes, all
> > > others are left in the cold. Sorry for that. 
> > 
> > Is there an easy opt out for that, other than booting a CONFIG_CGROUP=n
> > kernel?
> 
> systemd relies on CONFIG_CGROUP=y, since it useses it for service
> management. It creates its own name=systemd hierarchy for that with no
> controllers attached. If you turn that off, then systemd will refuse to
> boot.

Do expect distro bugzilla entries when this 'awesome'-ness hits the
street.

>  However, it does not rely on any of the controllers, and hence you
> are welcome to disable all cgroup controlls and systemd won't complain.
> 
> If you want to disable the automatic creation of groups in the 'cpu'
> hierarchy for user sessions then you can tell pam_systemd that by passing
> "controllers=" on the PAM config line. ("controllers=cpu" is the implied
> default.)
> 
> There's currently no global option to disable the same logic in systemd
> when it creates 'cpu' cgroups for the various services it runs. However,
> you can disable that individually with "ControlGroups=cpu:/" in the
> .service files. I will now add a global option as well.

A global knob is a must -- preferably with neon signs on so I can find
it.  Luckily I don't use this GNOME junk, otherwise I'd have had to ask
how to revert that crap as well.