[linux-dvb] Re: Fwd: Re: DEBI irq oops, crashes: kernel 2.6 &Hyperthreading unusable with DVB

[Michael Hunold <hunold@convergence.de>]

Hello Udo,

On 07.05.2004 16:56, Udo Wolter wrote:
> > There might be a race condition somewhere wrt SMP -- as Johannes already
> > pointed out, he'll have a look at it.
> Are there any kernel changes which could make my situation better ? The
> preemptive kernel parameter or the MSI vector based IRQs ? Or even
> vice versa, is it better to switch something off ? Or any other
> kernel parameter ?
Not really. Call it a race condition or something else -- it's a logical 
programming error that needs to be fixed when it comes to SMP or 
hyperthreading.

The two-staged notification and transfer mechanism of the av7110 makes 
it a little difficult to handle, because both CPUs can execute the 
tasklets scheduled by the irq handlers independently.

> I'd stand a lot if it just costs only 5% performance
> but I want to stay in hyperthreading. Switching off hyperthreading costs
> 30-40% performance. :(
In the meantime, you need to turn off hyperthreading and kernel 
preemption unless Johannes, me or someone else has fixed this problem 
thorougly.

> Mermgfurt,
> 		Udo
CU
Michael.


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