Re: [Xenomai-core] [PATCH 3/2] kill XN_INFINITE xntimer delays

[Jan Kiszka <jan.kiszka@domain.hid>]

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Philippe Gerum wrote:
> On Wed, 2006-07-19 at 12:20 +0200, Gilles Chanteperdrix wrote:
>> Jan Kiszka wrote:
>>  > [Appendix to the xntimer cleanup series.]
>>  > 
>>  > Having to take care for infinite delays in xntimer_start (i.e. to NOT
>>  > start the timer...) is a bit suboptimal given that his service might be
>>  > used heavily to restart timers. This patch converts the only user
>>  > (xnpod_start_timer again) and cleans up the timer code.
>>  > 
>>  > Jan
>>  > ---
>>  >  ksrc/nucleus/pod.c   |   10 ++++++----
>>  >  ksrc/nucleus/timer.c |   34 ++++++++++++----------------------
>>  >  2 files changed, 18 insertions(+), 26 deletions(-)
>>  > 
>>  > Index: xenomai/ksrc/nucleus/pod.c
>>  > ===================================================================
>>  > --- xenomai.orig/ksrc/nucleus/pod.c
>>  > +++ xenomai/ksrc/nucleus/pod.c
>>  > @@ -3095,10 +3095,12 @@ int xnpod_start_timer(u_long nstick, xni
>>  >  
>>  >  	xntimer_set_sched(&nkpod->htimer, xnpod_sched_slot(XNTIMER_KEEPER_ID));
>>  >  
>>  > -	xnlock_get_irqsave(&nklock, s);
>>  > -	xntimer_start(&nkpod->htimer, delta,
>>  > -		      XNARCH_HOST_TICK / nkpod->tickvalue);
>>  > -	xnlock_put_irqrestore(&nklock, s);
>>  > +	if (delta) {
>>
>> Should not this rather be if (XNARCH_HOST_TICK) ?
> 
> Both work, even if using the macro would get the unused code optimized
> away. The bottom line is that we need to refrain from starting the timer

Optimising away sounds good to me :). As we are already on it, I would
second Gilles' suggestion. It also makes the code more readable ("we do
not need the following when XNARCH_HOST_TICK is 0").

> whenever the delta value is zero, since it's a clear sign that
> XNARCH_HOST_TICK is zero in the first place. In all other cases, the
> delta value must be non-zero, even if the elapsed portion of the current
> tick is null.
> 
>>  > +		xnlock_get_irqsave(&nklock, s);
>>  > +		xntimer_start(&nkpod->htimer, delta,
>>  > +			      XNARCH_HOST_TICK / nkpod->tickvalue);
>>  > +		xnlock_put_irqrestore(&nklock, s);
>>  > +	}
>>



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