[Devel] Re: [RFC] Mount point suggestions for cgroup

KAMEZAWA Hiroyuki kamezawa.hiroyu at jp.fujitsu.com
Tue Nov 3 22:40:24 PST 2009

On Wed, 4 Nov 2009 12:00:05 +0530
Balbir Singh <balbir at linux.vnet.ibm.com> wrote:

> Hi, All,
> We've been having a discussion as to what would be the right place to
> mount the cgroup filesystem. Jan has been proactively looking into
> this. The FHS has no recommendation since cgroup filesystem came in
> much later.
> The options are
> 1. /dev/cgroup
> 2. /cgroup
> 3. Some place under /sys
> The problem with (2) is that it is quite non-standard and pollutes the
> root directory. (3) requires some basic support to create a directory
> for cgroup under /sys. (1) seems the most obvious choice since cpusets
> were mounted under /dev/cpuset, but /dev is controlled by udev.
> Given the three choices or any other suggestions, is there a general
> preference as to where we can mount it? The goal is to standardize
> the mount point (if possible).
> BTW, the mounting is expected to be done using cgconfigparser present
> in libcgroup.

IMHO, even if anywhere is ok to me, the suggestion should includes the fact
  - Each cgroup subsystem can be mounted independenty from other cgroup.
  - some cgroup (noop) can be mounted multiple times
etc...there are some points which is different from /proc or /sys.
So, we need multiple mount points.

Then, to say my own not-seriously-considered idea, I vote for
 - /cgroup/[HierarchyName]/
rather than /dev/ or /sys or /opt. This sounds straightforward.

If /sys,  /sys/cgroup/[HierarchyName] will be candidate. But considering
users can use arbitarary combination of subsystem, using /sys may require
much work, I think.


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