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Date: Tue, 02 Jan 2007 14:56:57 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: [Xenomai-core] Re: SVN checkin #2010
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To: rpm@xenomai.org
Cc: Jan Kiszka <jan.kiszka@domain.hid>, xenomai-core <xenomai@xenomai.org>

Philippe Gerum wrote:
> On Tue, 2007-01-02 at 14:30 +0100, Gilles Chanteperdrix wrote:
> 
>>Philippe Gerum wrote:
>>
>>>On Tue, 2007-01-02 at 11:20 +0100, Jan Kiszka wrote:
>>>
>>>
>>>>Hi all - and happy new year,
>>>>
>>>>I haven't looked at all the new code yet, only the commit messages. I
>>>>found something similar to my fast-forward-on-timer-overrun patch in
>>>>#2010 and wondered if Gilles' original concerns on side effects for the
>>>>POSIX skin were addressed [1]. I recalled that my own final summary on
>>>>this was "leave it as it is" [2].
>>>>
>>>
>>>
>>>The best approach is to update the POSIX skin so that it does not rely
>>>on the timer code to act in a sub-optimal way; that's why this patch
>>>found its way in. Scheduling and processing timer shots uselessly is a
>>>bug, not a feature in this case.
>>
>>There is some work to be done on the posix skin anyway, this will all be
>>at once. By the way, I tested the trunk on ARM, and I still get a lockup
>>when the latency period is too low. I wonder if we should not compare to
>>"now + nkschedlat", or even use xnarch_get_cpu_tsc() instead of "now".
> 
> 
> You mean as below, in order to account for the time spent in the handler(s)?	
> 
> -	while ((xntimerh_date(&timer->aplink) += timer->interval) < now)
> +	while ((xntimerh_date(&timer->aplink) += timer->interval) < xnarch_get_cpu_tsc())
> 		    ;
> 

I mean even:

	while ((xntimerh_date(&timer->aplink) += timer->interval) <
		xnarch_get_cpu_tsc() + nkschedlat)
                 ;

Because if the timer date is between now and now + nkschedlat, its
handler will be called again.

-- 
                                                 Gilles Chanteperdrix