Re: [RFC] Mount point suggestions for cgroup

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-11-04 15:40:24]:

> On Wed, 4 Nov 2009 12:00:05 +0530
> Balbir Singh <balbir@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.

The reason I liked /dev/cgroup was because cpusets could be
mounted at /dev/cpuset or /dev/cgroup/cpuset. My concern with /cgroup
is that a ls "/" now becomes larger in size. But I'll take your vote
for it as +1 for /cgroup.

> 
> 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.
> 

Yes, Agreed.

> Thanks,
> -Kame
> 

-- 
	Balbir