[systemd-devel] dbus interface for disabling default cgroups

Daniel Poelzleithner poelzi at poelzi.org
Sun Feb 13 15:38:23 PST 2011


On 02/13/2011 10:36 PM, Lennart Poettering wrote:


> Note that pam_systemd in git now explicitly resets the "cpu" cgroup of
> all sessions to the root group since otherwise RT scheduling will not be
> available for any user daemons. This is a general limitation of the
> "cpu" scheduler right now, and makes it impractical to muck around with
> it for generic sessions.

I stumbled on this one too, but got it fixed by giving the most cgroups
a rt_sched_slice of 1. this way they can be set to rt and then, move the
process to a group with more rt slice if there is a rule to move it there.


>> org.freedesktop.systemd1.Manager.ChangeController(string subsystem,
>> boolean enable, boolean clear)
> 
> Nah, if at all then the controller property should just become
> writable. But to be frank I am not sure we actually want to make this
> changeable at runtime.

If the admin decides he wants to run a program that optimizes the system
better, he already made this decision.
If it is required for the user to edit a config file so one service can
run, he doesn't have the freedom to run it when it fits best.
Another, maybe more important reason is, that the most optimisations
will be on a running, not starting system. If the config must be
changed, ulatencyd for example should be started very early, while it
may do a poorly job at at. It optimises extremely good when the user is
using the computer, not booting it. If the property can be changed at
runtime, ulatency could simply be started when most stuff is up, that
would be perfect.


kind regards
 daniel

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