Date: Wed, 4 Nov 2009 15:40:24 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: balbir@linux.vnet.ibm.com
Cc: libcg-devel <libcg-devel@lists.sourceforge.net>,
       "menage@google.com" <menage@google.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       containers@lists.linux-foundation.org,
       Jan Safranek <jsafrane@redhat.com>,
       Dhaval Giani <dhaval@linux.vnet.ibm.com>,
       Bharata B Rao <bharata.rao@in.ibm.com>
Subject: Re: [RFC] Mount point suggestions for cgroup
Message-Id: <20091104154024.0b8f6123.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <20091104063005.GC3560@balbir.in.ibm.com>
References: <20091104063005.GC3560@balbir.in.ibm.com>
Organization: FUJITSU Co. LTD.
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1849
Lines: 51

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.

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.

Thanks,
-Kame

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/