[RFC PATCH v2 4/5] drm, cgroup: Add total GEM buffer allocation limit

[Kenny Ho]

On Thu, May 16, 2019 at 10:10 AM Tejun Heo <tj at kernel.org> wrote:
> I haven't gone through the patchset yet but some quick comments.
>
> On Wed, May 15, 2019 at 10:29:21PM -0400, Kenny Ho wrote:
> > Given this controller is specific to the drm kernel subsystem which
> > uses minor to identify drm device, I don't see a need to complicate
> > the interfaces more by having major and a key.  As you can see in the
> > examples below, the drm device minor corresponds to the line number.
> > I am not sure how strict cgroup upstream is about the convention but I
>
> We're pretty strict.
>
> > am hoping there are flexibility here to allow for what I have
> > implemented.  There are a couple of other things I have done that is
>
> So, please follow the interface conventions.  We can definitely add
> new ones but that would need functional reasons.
>
> > not described in the convention: 1) inclusion of read-only *.help file
> > at the root cgroup, 2) use read-only (which I can potentially make rw)
> > *.default file instead of having a default entries (since the default
> > can be different for different devices) inside the control files (this
> > way, the resetting of cgroup values for all the drm devices, can be
> > done by a simple 'cp'.)
>
> Again, please follow the existing conventions.  There's a lot more
> harm than good in every controller being creative in their own way.
> It's trivial to build convenience features in userspace.  Please do it
> there.
I can certainly remove the ro *.help file and leave the documentation
to Documentation/, but for the *.default I do have a functional reason
to it.  As far as I can tell from the convention, the default is per
cgroup and there is no way to describe per device default.  Although,
perhaps we are talking about two different kinds of defaults.  Anyway,
I can leave the discussion to a more detailed review.

Regards,
Kenny