Re: [PATCH 07/13] rv: Simply hybrid automata monitors's clock variables

[Gabriele Monaco <gmonaco@redhat.com>]

On Mon, 2026-05-18 at 09:44 +0200, Nam Cao wrote:
> Gabriele Monaco <gmonaco@redhat.com> writes:
> > On Mon, 2026-05-11 at 13:55 +0200, Nam Cao wrote:
> > > That can work, but not ideal, because hrtimer will not be usable.
> > 
> > Why not? If we have HA_TIMER_WHEEL , we'd use timer and expire, if we have
> > HA_TIMER_HRTIMER we'd only need hrtimer with it's hrtimer_get_expires():
> > 
> >  union {
> >  struct hrtimer hrtimer;
> >  struct {
> >  struct timer_list timer;
> >  u64 expire; /* Explicitly store the armed budget */
> >  };
> > 
> > we already can't use timer and hrtimer interchangeably.
> > What am I missing here?
> 
> Ah, now I understand the trick, thanks.
> 
> We already have an "expires" field in struct timer_list. But I am not
> sure if we are supposed to touch that field. Your proposal looks safer.

Yeah and even if we did, that'd be jiffy-granularity, so not good if the clock
is ns-based.

Let me sketch it out.

Anyway back to the patch, you need to fix the build for HA_TIMER_HRTIMER as well
(too many arguments to function ‘ha_invariant_passed_ns’; expected 3, have 4),
and the title should s/Simply/Simplify/

Thanks,
Gabriele

> 
> > > Looking at the throttle monitor again, is it possible to rewrite
> > > runtime_left_ns() to read .dl_runtime instead of .runtime? I don't know
> > > the deadline schedule very well, but I think .dl_runtime is not changing
> > > like .runtime?
> > 
> > In theory yes, but since the runtime is consumed only when running, we
> > cannot
> > just set the timeout once. We either save how much was consumed somewhere or
> > do
> > some start/pause mechanism.
> > Neither looks simpler to me.
> 
> Understood.
> 
> Nam