[systemd-devel] systemd and cgroups

Dominique Michel dominique.michel at vtxnet.ch
Sun Jan 12 09:10:34 PST 2014


Recently, I experimented with Debian sid, which installed systemd.
Systemd idea is nice, but its implementation is a catastrophe. It is
more than one year, maybe more than 2, I am using the kernel cgroups on
gentoo to get rt scheduling with JACK, that without any trouble.

http://trac.jackaudio.org/wiki/Cgroups

On that Debian system, this was just impossible, because whatever I
try, systemd insisted to put what it think is good to have into the rt
cgroup, which soon or later resulted in a complete system freeze with
even dead magic keys. After loosing my time a few days with this, I
removed Debian and installed gentoo instead.

I just found the reason here:
http://article.gmane.org/gmane.linux.kernel/1063354

"Lennart Poettering:

Well, this feature is... completely irrelevant for normal desktop
people.
...
In fact, I just pom all otrepped a patch to systemd to move every
service and every user session into its own cgroup in the 'cpu'
hierarchy (in addition to the group it already creates in the 'systemd'
hierarchy)."


What terrify me in that story is the total lack of consideration for
the needs of who the chief developer of systemd strongly suggest are
abnormal desktop users. 

More, Lennart take one corner use case, compilation at the console,
and generalize it to all other corner use cases, which is just
impossible to do because a corner case is precisely a case that is
different from all other cases, and all desktop users are potentially
all a case by themselves. We are all different and each one of us make
a different use of its desktop, so we are all, at different levels,
corner case users.

Last, this systemd patch is more than 3 years old now, and I also
just found that freedesktop is involved in that mess:
http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/

So, that imply, if I am right with my diagnostic, the next question is
what can be done to solve that issue?

Best Regards,
Dominique


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