Sebastian Smolorz wrote:
> Gilles Chanteperdrix wrote:
> > Sebastian Smolorz wrote:
> > > Sebastian Smolorz wrote:
> > > > Gilles Chanteperdrix wrote:
> > > > > Schlägl "Manfred jun." wrote:
> > > > > > Hi again!
> > > > > >
> > > > > > I've the presumption, there is something wrong with my
> > > > > > timer-handling. Could you please take a look at my handling.
> > > > > >
> > > > > > Thanks in advance!
> > > > >
> > > > > The problem I see with your code is that you are updating
> > > > > ns_timer_lxlost in __ipipe_mach_acktimer, the integrator
> > > > > architecture code, which also uses a decrementer does not do that.
> > > > > Apart from that, I see nothing wrong.
> > > >
> > > > I see another one which has to do with the fact that __ipipe_mach_tsc
> > > > is updated both in __ipipe_mach_get_tsc and __ipipe_mach_set_dec. This
> > > > leads to double-added ticks because the latter funcion is called only
> > > > once a period and the former even more than once. So Xenomai counts
> > > > jiffies in /proc/xenomai/timer to fast. Manfred, can you confirm this?
> > >
> > > Forget this, my eyes weren't open this morning ... In
> > > __ipipe_mach_get_tsc there is no update of __ipipe_mach_tsc, of course.
> >
> > Right, but __ipipe_mach_tsc and ns_timer_lxlost get also updated in
> > __ipipe_mach_acktimer, this looks wrong, in the integrator
> > implementation, they are updated in the timer interrupt, only if the
> > timer is not stolen.
>
> OK, let's speculate a little bit. (Maybe all of the following turns out to
> be
> completely wrong, but it wouldn't be the first time for me today. ;-)
> Hopefully Manfred can give some comments which pieces of my speculation are
> right.)
>
> The timer counts down to zero, causes an interrupt and then reloads
> automatically with ns_timer_reload. So, when __ipipe_mach_acktimer is called
> ns_timer_reload ticks have passed and can be added to __ipipe_mach_tsc and
> ns_timer_lxlost. Some ticks later, __ipipe_mach_set_dec is executed, the
> passed ticks are added to __ipipe_mach_tsc and ns_timer_lxlost and the timer
> is reprogrammed to the new value.
The problem is that when Xenomai manages the timer, it get reloaded with
values distinct from ns_timer_reload, it is even not reloaded at all
when the system is a bit late, so adding ns_timer_reload to
__ipipe_mach_tsc and ns_timer_lxlost in these cases seem wrong.
--
Gilles Chanteperdrix.
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