>
> On Fri, Dec 5, 2008 at 8:40 AM, John Keller <jpk@xxxxxxx> wrote:
> > The addition of the generic affinity autoselector has introduced
> > a regression in SN2 Altix.
> >
> > In the past, request_irq()'s call to select_smp_affinity() was
> > essentially a noop.
> >
> > #ifdef CONFIG_AUTO_IRQ_AFFINITY
> > extern int select_smp_affinity(unsigned int irq);
> > #else
> > static inline int select_smp_affinity(unsigned int irq)
> > {
> > return 1;
> > }
> >
> >
> > Now changes have created do_irq_select_affinity(), which is
> > executed by a call to request_irq().
> >
> > request_irq()
> > __setup_irq()
> > do_irq_select_affinity()
> >
> > do_irq_select_affinity() will call the set_affinity() routine,
> > with a default mask. On SN2 (and possibly all ia64 platforms),
> > this will retarget all device interrupts to the same CPU, most
> > likely CPU0.
>
> > I'm looking at a patch that makes use of the new IRQ_AFFINITY_SET
> > flag in the irq_desc to get around this.
> >
>
> that bit only be set in irq_set_affinity(),
>
> arch/mips/kernel/cevt-bcm1480.c: irq_set_affinity(irq,
> cpumask_of_cpu(cpu));
> arch/mips/kernel/cevt-sb1250.c: irq_set_affinity(irq, cpumask_of_cpu(cpu));
> arch/sparc64/kernel/of_device.c: irq_set_affinity(irq,
> numa_mask);
> arch/sparc64/kernel/pci_msi.c: irq_set_affinity(irq, numa_mask);
> arch/x86/kernel/hpet.c: irq_set_affinity(hdev->irq,
> cpumask_of_cpu(hdev->cpu));
> arch/x86/kernel/hpet.c: irq_set_affinity(dev->irq, cpumask_of_cpu(dev->cpu));
> drivers/xen/events.c: irq_set_affinity(irq, cpumask_of_cpu(0));
>
> kernel/irq/proc.c: irq_set_affinity(irq, new_value);
>
> kernel/time/tick-common.c: irq_set_affinity(newdev->irq, *cpumask);
>
> so you may need to call it in your arch code. like
> setup_IO_APIC_irq(), create_irq()...
>
> YH
>
Yes, I am planning to set it in SN platform specific code,
sn_irq_fixup().
John
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