On 12/30/2013 02:44 AM, Chen, Gong wrote:
> On Sat, Dec 28, 2013 at 12:10:38PM -0500, Prarit Bhargava wrote:
>> Gong and Rui,
>>
>> After looking at this in detail I realized I made a mistake in my patch by
>> including the check for the smp_affinity. Simply put, it shouldn't be there
>> given Rui's explanation above.
>>
>> So I think the patch simply needs to do:
>>
>> this_count = 0;
>> for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
>> irq = __this_cpu_read(vector_irq[vector]);
>> if (irq >= 0) {
>> desc = irq_to_desc(irq);
>> data = irq_desc_get_irq_data(desc);
>> affinity = data->affinity;
>> if (irq_has_action(irq) && !irqd_is_per_cpu(data))
>> this_count++;
>> }
>> }
>>
>> Can the two of you confirm the above is correct? It would be greatly
>> appreciated.
>>
>
> No, I don't think it is correct. We still need to consider smp_affinity.
>
> fixup_irqs
> irq_set_affinity(native_ioapic_set_affinity)
> __ioapic_set_affinity
> assign_irq_vector
> __assign_irq_vector
> cpu_mask_to_apicid_and
> /* now begin to set ioapic RET */
>
> __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
> {
> ...
> apic->vector_allocation_domain(cpu, tmp_mask, mask);
> ...
> for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
> per_cpu(vector_irq, new_cpu)[vector] = irq;
> cfg->vector = vector;
> cpumask_copy(cfg->domain, tmp_mask);
> ...
> }
>
> On same vecotr on all related vector_irq, irq is set. So such kind of
> irq should happen in multiple vector_irq. In cpu_mask_to_apicid_and(e.g.
> x2apic_cpu_mask_to_apicid_and for cluster mode), apic is updated
> depending on new mask. That's why I think this kind of interrupt
> should be bypassed.
Hmm ... okay. I'll take a closer look at this.
Thanks for the additional information.
P.
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