On Tue, Jan 30, 2018 at 06:56:39AM -0800, Tejun Heo wrote: > Hello, > > On Tue, Jan 30, 2018 at 11:21:56AM +0100, Peter Zijlstra wrote: > > afaiu the existing code does exactly the opposite, it forces the > > descendants to configure less than the parent allows. > > > > You're taking out an error condition and silently allowing descentant > > misconfiguration. How does that make sense? > > Well, they're upper limits, not strict allocations. The current > behavior implemented by cpu isn't either a strict allocation or upper > limits. It disallows a child from having a value higher than the > parent (allocation-ish) but the sum of the children is allowed to > exceed the parent's (limit-ish).
True; but its still weird to have the parent 'promise' something and then retract that 'promise' later. > The combination is rather arbitrary and makes it impossible to > delegate safely (a delegatee can block the delegator from reducing the > amount resource allocated to the delegatee) while not really > protecting against overcommit from descendants either. > > We had this sort of input validations in different controllers all in > their own ways. In most cases, these aren't well thought out and we > can't support things like delegation without aligning controller > behaviors. I suppose.. Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
