Re: [RFC][PATCH -rt] irqd starvation on SMP by a single process?

john stultz
2006-05-12T17:47:47Z

On Fri, 2006-05-12 at 07:50 +0200, Ingo Molnar wrote:
> * john stultz <johnstul@us.ibm.com> wrote:
> > + if(!cpus_equal(current->cpus_allowed, irq_affinity[irq]));
> > + set_cpus_allowed(current, irq_affinity[irq]);
>
> > The patch below appears to correct this issue, however it also
> > repeatedly(on different irqs) causes the following BUG:
>
> ah. This actually uncovered a real bug. We were calling __do_softirq()
> with interrupts enabled (and being preemptible) - which is certainly
> bad.
>
> this was hidden before because the smp_processor_id() debugging code
> handles tasks bound to a single CPU as per-cpu-safe.
>
> could you check the (totally untested) patch below and see if that fixes
> things for you? I've also added your affinity change.

Yep, no BUG messages and I get irq affinity behavior that matches what I
echo into the proc interface.

Looks good to me so far. I'll keep running w/ it and let you know if we
see any issues.

thanks
-john