[Devel] Re: [PATCH v3 04/13] kmem accounting basic infrastructure

[Tejun Heo]

Hello, Michal, Glauber.

On Wed, Sep 26, 2012 at 04:03:47PM +0200, Michal Hocko wrote:
> Haven't we already discussed that a new memcg should inherit kmem_accounted
> from its parent for use_hierarchy?
> Say we have
> root
> |
> A (kmem_accounted = 1, use_hierachy = 1)
>  \
>   B (kmem_accounted = 0)
>    \
>     C (kmem_accounted = 1)
> 
> B find's itself in an awkward situation becuase it doesn't want to
> account u+k but it ends up doing so becuase C.

Do we really want this level of flexibility?  What's wrong with a
global switch at the root?  I'm not even sure we want this to be
optional at all.  The only reason I can think of is that it might
screw up some configurations in use which are carefully crafted to
suit userland-only usage but for that isn't what we need a transition
plan rather than another ultra flexible config option that not many
really understand the implication of?

In the same vein, do we really need both .kmem_accounted and config
option?  If someone is turning on MEMCG, just include kmem accounting.

Thanks.

-- 
tejun