Re: [PATCH 1/3] clockevents: Retry programming min delta up to 10 times

[Matt Redfearn]

On 19/10/17 13:43, Thomas Gleixner wrote:
> On Thu, 19 Oct 2017, Matt Redfearn wrote:
> >   	unsigned long long clc;
> >   	int64_t delta;
> > +	int i;
> >   
> > -	delta = dev->min_delta_ns;
> > -	dev->next_event = ktime_add_ns(ktime_get(), delta);
> > +	for (i = 0;;) {
> Bah. What's wrong with
>
> 	for (i = 0; i < 10; i++) {
>
> 	    	....
> 		if (!(dev->set_next_event((unsigned long) clc, dev))
> 			return 0;
> 	}
> 	return -ETIME;
>
> Hmm?

Sure, can make it like that.

> > +		delta = dev->min_delta_ns;
> > +		dev->next_event = ktime_add_ns(ktime_get(), delta);
> >   
> > -	if (clockevent_state_shutdown(dev))
> > -		return 0;
> > +		if (clockevent_state_shutdown(dev))
> > +			return 0;
> >   
> > -	dev->retries++;
> > -	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
> > -	return dev->set_next_event((unsigned long) clc, dev);
> > +		dev->retries++;
> > +		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
> I'd rather make that:
>
> 	delta = 0;
> 	for (i = 0; i < 10; i++) {
> 		delta += dev->min_delta_ns;
> 		dev->next_event = ktime_add_ns(ktime_get(), delta);
> 		clc = .....
> 	   	.....
>
> That makes it more likely to succeed fast. Hmm?

That will set the target time to increasing multiples of min_delta_ns in 
the future, right? Sure, it should make it succeed faster - I'll make it 
like that. Are you OK with the arbitrarily chosen 10 retries?

Thanks,
Matt

> Thanks,
>
> 	tglx