[lxc-devel] [PATCH 1/5] cgroup: minor bugfixes so start and attach work again

[Christian Seiler]

Hi Serge,

>> I do have a very stupid question, however: LXC 0.9 used to set the
>> cgroup to /lxc/$name. Now it's just /$name. Is that intentional?
> 
> Hm, it was somewhat unconscious but I didn't really mean to do that.
> Some cgroup subsystems do incur a performance penalty for every
> extra directory we descend.  But /lxc does make for a nice grouping.
> 
> Do you (and others) have a preference?  Should we stick with /lxc?

Well, thinking about it again, libvirt [1] seems to have adopted the
layout /machine/$name.libvirt-$type in current versions, which doesn't
seem unreasonable to me, so maybe we should go with

/machine/$name.lxc

in analogy to that scheme. Personally I don't use libvirt-lxc but I do
use libvirt-qemu (although currently in an older version which still
uses a legacy cgroup layout), so at least for me the /machine cgroup
will probably exist anyway in the future.

Also according to the same document [1], libvirt supports additional
subdividing in the form of /machine/$foo.partition as a base dir, which
doesn't seem to be a bad idea if you want to have some common resource
limits on for example all machines of a given user. We could also
support that in the form of an additional configuration option - i.e.
use /machine/$name.lxc by default and allow for the usage of
/machine/$foo.partition/$bar.lxc if a configuration option is specified.
I can provide a patch for that if you wish.

Just my 2¢.

[1] http://libvirt.org/cgroups.html

-- Christian