Re: [PATCH] x86: enable preemption in delay

[Pavel Machek]

On Wed 2008-05-28 09:01:06, Steven Rostedt wrote:
> 
> 
> On Sun, 25 May 2008, Pavel Machek wrote:
> > > +		if (unlikely(cpu != smp_processor_id())) {
> > > +			if (loops <= TSC_MIGRATE_COUNT)
> > > +				break;
> > > +			cpu = smp_processor_id();
> > > +			rdtscl(bclock);
> > > +			loops -= TSC_MIGRATE_COUNT;
> > > +		} else {
> > > +			rdtscl(now);
> > > +			if ((now - bclock) >= loops)
> > > +				break;
> > > +			loops -= (now - bclock);
> > > +			bclock = now;
> >
> > What happens with different cpus running on different frequencies...?
> > Cpufreq?
> 
> It's not even protected with the old code.

Maybe, but it is simple to fix as long as preemption is disabled. When
you enable it, it becomes much harder.

Lets get that fixed.
							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/