Re: clarification about misc controller and capacity vs. max

["tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

Hello,

On Tue, Nov 01, 2022 at 04:40:22PM +0000, Accardi, Kristen C wrote:
> I notice in the comments for the misc controller it is stated that the
> max limit can be more than actual total capacity, meaning that we can
> overcommit with the resource controlled by the misc controller.
> However, in the misc_cg_try_charge() code, the function will return -
> EBUSY if max limit will be crossed or total usage will be more than the
> capacity, which would seem to enforce total capacity as an upper limit
> in addition to max and not allow for overcommit. Can you provide some
> clarity on whether the resource consumption model for the misc
> controller should allow for overcommit?

I think what it's trying to say is that the sum of first level .max's can be
higher than the total capacity. e.g. Let's say you have 5 of this resource
and a hierarchy like the following.

        R - A - A'
          + B - B'
          \ C

It's valid to have A, B, C's max set to 4, 3, 2 respectively even if they
sum up to 9 which is larger than what's available in the system, 5 - ie. the
max limits are overcommitted for the resource.

Thanks.

-- 
tejun