Re: [Patch v3 0/2] cgroup: New misc cgroup controller

Michal Koutný
2021-03-15T19:10:50Z

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On Fri, Mar 12, 2021 at 09:49:26AM -0800, Vipin Sharma <vipinsh@google.com> wrote:
> I will add some more information in the cover letter of the next version.
Thanks.

> Each one coming up with their own interaction is a duplicate effort
> when they all need similar thing.
Could this be expressed as a new BPF hook (when allocating/freeing such
a resource unit)?

The decision could be made based on the configured limit or even some
other predicate.

(I saw this proposed already but I haven't seen some more reasoning
whether it's worse/better. IMO, BPF hooks are "cheaper" than full-blown
controllers, though it's still new user API.)

> As per my understanding this is the only for way for loadable modules
> (kvm-amd in this case) to access Kernel APIs. Let me know if there is a
> better way to do it.
I understood the symbols are exported for such modularized builds.
However, making them non-GPL exposes them to any out-of-tree modules,
although, the resource types are supposed to stay hardcoded in the misc
controller. So my point was to make them EXPORT_SYMBOL_GPL to mark
they're just a means of implementing the modularized builds and not an
API. (But they'd remain API for out-of-tree GPL modules anyway, so take
this reasoning of mine with a grain of salt.)

Michal

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