Re: cgroup mount point

[Paul Menage <menage@google.com>]

On Tue, Feb 3, 2009 at 10:51 AM, sean finney <seanius@seanius.net> wrote:
> On Tue, Feb 03, 2009 at 07:49:15PM +0100, Mike Hommey wrote:
>> > Having one virtual filesystem mounted on top of another virtual
>> > filesystem seems like a recipe for problems.
>>
>> Like with /sys/fs/fuse/connections ? Come on, there is no problem with a
>> virtual filesystem mounted on top of another.
>
> or /proc/bus/usb or /dev/shm or /dev/pts... :)
>

/dev is a bit different though - even if it's mounted as a udev fs,
you can create a new directory in there to act as a mount point.

Cgroups supports multiple hierarchies on different mount points.

So if you have two cgroups hierarchies - say one for CPU/network and
one for memory isolation, you could create /dev/cgroup/cpunet and
/dev/cgroup/memory and mount the two hierarchies. But sysfs doesn't
allow you to create new subdirectories to act as mountpoints. If we
can have a /sys/cgroups directory which allows you to create arbitrary
subdirs to act as mountpoints, that could be OK.

Or just fake it by mounting a tmpfs on /sys/cgroups and then create
mount points in there, but that seems like a bit of a hack.

Paul