Re: cgroup mount point

[Daniel P. Berrange]

On Tue, Feb 03, 2009 at 10:30:28AM -0200, Thadeu Lima de Souza Cascardo wrote:
> Sorry. I didn't mean to imply that libvirt or Fedora did anything in
> respect to the mountpoint themselves. But that they are supporting or
> planning to support cgroups. And I think that one time we will need to
> sort the problem of the mountpoint, either let the applications mount it
> (in this case, libvirt) or the system do it (Fedora install, Debian
> initscripts, et al).
>
> I have some experience with lxc tools from http://lxc.sf.net/ and these
> tools also look up the mountpoint at /proc/mounts. So it is up to the
> system or the user to mount it.

That's good. We settled on letting mount points be OS / admin defined
in libvirt, because we felt libvirt shouldn't try to impose a mount
policy on a resource that will have many users & we are able to work
with whatever mount hierarchy the admin / OS decided to setup.

> > Putting new mount points in / is not really acceptable, so that rules
> > out the first two. /opt is just totally wrong, since that is intended
> > for add on software packages. /dev/ feels a little odd, since it is
> > not really device nodes, but perhaps that doesn't matter. So my pref
> > would be something in /dev/cgroups or /sys/cgroups
> 
> My suggestions were /proc/cgroup, /sys/cgroup, /cgroup or /dev/cgroup. I
> sent the problems with the former two, and the rationale for the latter
> two in a previous message.
> 
> I agree that /opt/ is not the place for it (and that's the one I called
> 'funny'). I've head some people telling that /dev/ is for devices, but I
> can't see a problem (/dev/log is a socket and it is there, the FHS
> refers to special files).
> 
> /proc/ and /sys/ are two good options if the kernel does not put anything
> else there. /proc/cgroups already exist, for example.
> 
> Could you please give your rationale why / is not really acceptable?
 
Just a general preference is to not continually add more ad-hoc top 
level directories to /, when there are other places in the filesystem
hierarchy that are available, such as /sys or /proc. 

> > I also think 'cgroups' is a better name than 'containers', since 
> > 'containers' is refering to just one specific use case.
> 
> Agreed on this one, although I still prefer the singular (it is also the
> name of the filesystem type).

Either singular / plural sounds fine to me

Regards,
Daniel
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