Re: [PATCH v2 10/20] rv: Add Hybrid Automata monitor type

[Nam Cao <namcao@linutronix.de>]

Gabriele Monaco <gmonaco@redhat.com> writes:
> Alright, that /should/ be possible, provided the value used to set invariants is
> constant or at least doesn't change until we leave the state.
> This seems a fair assumption to make but doesn't stand for the throttle monitor,
> in that case I read the remaining runtime from the dl entity, that one is
> updated frequently, for instance when a task is throttled, it's negative, but
> this doesn't mean the invariant should expect time to be negative.
>
> Runtime is consumed only when a task is running, so here I use an invariant set
> up on the /remaining/ runtime when reaching the running state, that's why also
> switch_in resets the clock (runtime is not replenished, but the runtime_left
> value doesn't need to be subtracted anything).
>
> An alternative would be to have some sort of pause/resume operations on clocks,
> and a task would just pause the clock when preempted, but those operations are
> not backed up by theory and wouldn't really simplify the implementation (use 2
> variables per clock or a single one and some hack to mark it as paused).
>
> Again, there may be better ways, but I found this one the "simplest".
>
> Does it makes sense or am I just crystallising to this implementation?

Ok, now it makes sense.

I have been thinking about this in the past days, and didn't come up
with anything better. Let's leave it be.

Nam