From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Wagner <wagi@monom.org>
Subject: Re: [PATCH v0 5/5] cgroup: Assign subsystem IDs during compile time
Date: Fri, 17 Aug 2012 10:48:18 +0200
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To: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>, netdev@vger.kernel.org, cgroups@vger.kernel.org, Daniel Wagner <daniel.wagner@bmw-carit.de>, "David S. Miller" <davem@davemloft.net>, Andrew Morton <akpm@linux-foundation.org>, Eric Dumazet <edumazet@google.com>, Gao feng <gaofeng@cn.fujitsu.com>, Glauber Costa <glommer@parallels.com>, Jamal Hadi Salim <jhs@mojatatu.com>, John Fastabend <john.r.fastabend@intel.com>, Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Neil Horman <nhorman@tuxdriver.com>

On 17.08.2012 09:25, Li Zefan wrote:
> On 2012/8/17 7:20, Tejun Heo wrote:
>> On Thu, Aug 16, 2012 at 04:12:16PM +0200, Daniel Wagner wrote:
>>> From: Daniel Wagner <daniel.wagner@bmw-carit.de>
>>>
>>> We are able to safe some space when we assign the subsystem
>>> IDs at compile time. Instead of allocating per cgroup
>>> cgroup->subsys[CGROUP_SUBSYS_COUNT] where CGROUP_SUBSYS_COUNT is
>>> always 64, we allocate 12 + 1 at max (at this point there are 12
>>> subsystem).
>>
>> So, IIUC, this is effectively removing the capability to implement
>> modularized controller which isn't known at kernel compile time.  Am I
>> right?
>>
>
> I think so.

I am preparing an updated version which does not need the extra 1 
pointer. Some more preprocessor magic involved :)

>> I don't think that's a bad idea but if we're doing that, can't we make
>> things even simpler?  Do we need to distinguish in-kernel and module
>> at all?
>>
>> Li, what do you think about this?
>>
>
> I'm definitely all for simplicity, but I'm not sure if we can do better in
> simplifying the code for modularized cgroup subsystem. (I guess you didn't
> mean to remove this feature?)

The new version should also be simpler to review because I don't have to 
touch the loops everywhere.

daniel