[lxc-devel] cgroup management daemon

[Serge E. Hallyn]

Quoting Tim Hockin (thockin at google.com):
> At the start of this discussion, some months ago, we offered to
> co-devel this with Lennart et al.  They did not seem keen on the idea.
> 
> If they have an established DBUS protocol spec,

see http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/
and http://man7.org/linux/man-pages/man5/systemd.cgroup.5.html

>  we should consider
> adopting it instead of a new one, but we CAN'T just play follow the
> leader and do whatever they do, change whenever they feel like
> changing.

Right.  And if we suspect that the APIs will always be at least
subtly different, then keeping them obviously visually different
seems to have some benefit.  (i.e. 
	systemctl set-property httpd.service CPUShares=500 MemoryLimit=500M
vs
	dbus-send cgmanager set-value http.server "cpushares:500 memorylimit:500M swaplimit:1G"
) rather than have admins try to remember "now why did that not work
here, oh yeah, MemoryLimit over here should be Memorylimit" or whatever.

Then again if lmctfy is the layer which admins will use, then it
doesn't matter as much.

> It would be best if we could get a common DBUS api specc'ed and all
> agree to it.  Serge, do you feel up to that?

Not sure what you mean - I'll certainly send the API to these lists as
the code is developed, and will accept all feedback that I get.  My only
requirements are that the requirements I've listed in the document
be feasible, and be feasible back to, say, 3.2 kernels.  So that is
why we must send an scm-cred for the pid to move into a cgroup.  (With
3.12 we may have alterntives, accepting a vpid as a simple dbus message
and setns()ing into the requestor's pidns to echo the pid into the
cgroup.tasks file.)

-serge