Re: [PATCH v0 5/5] cgroup: Assign subsystem IDs during compile time

On 17.08.2012 09:25, Li Zefan wrote:

On 2012/8/17 7:20, Tejun Heo wrote:

quoted

On Thu, Aug 16, 2012 at 04:12:16PM +0200, Daniel Wagner wrote:

quoted

From: Daniel Wagner <redacted>

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 :)

quoted

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