On 12/30/2013 09:58 PM, rui wang wrote:
> On 12/30/13, Prarit Bhargava <pra...@redhat.com> wrote:
>>
>>
>> On 12/30/2013 07:56 AM, rui wang wrote:
>>
> ...
>> Okay, so the big issue is that we need to do the calculation without this
>> cpu,
>
>>
>> int check_irq_vectors_for_cpu_disable(void)
>> {
>> int irq, cpu;
>> unsigned int vector, this_count, count;
>> struct irq_desc *desc;
>> struct irq_data *data;
>> struct cpumask online_new; /* cpu_online_mask - this_cpu */
>> struct cpumask affinity_new; /* affinity - this_cpu */
>>
>> cpumask_copy(&online_new, cpu_online_mask);
>> cpu_clear(smp_processor_id(), online_new);
>>
>> 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);
>> cpumask_copy(&affinity_new, data->affinity);
>> cpu_clear(smp_processor_id(), affinity_new);
>> if (irq_has_action(irq) && !irqd_is_per_cpu(data) &&
>> !cpumask_subset(&affinity_new, &online_new) &&
>> !cpumask_empty(&affinity_new))
>
> If this cpu is the only target, then affinity_new becomes empty.
> Should we count it for migration?
Okay, how about,
if (irq_has_action(irq) && !irqd_is_per_cpu(data) &&
((!cpumask_empty(&affinity_new)) &&
!cpumask_subset(&affinity_new, &online_new)) ||
cpumask_empty(&affinity_new))
this_count++;
I tried this with the following examples and AFAICT I get the correct result:
1) affinity mask = online mask = 0xf. CPU 3 (1000b) is down'd.
this_count is not incremented.
2) affinity mask is a non-zero subset of the online mask (which IMO is
the "typical" case). For example, affinity_mask = 0x9, online mask = 0xf. CPU
3 is again down'd.
this_count is not incremented.
3) affinity_mask = 0x1, online mask = 0x3. (this is your example). CPU
1 is going down.
this_count is incremented, as the resulting affinity mask will be 0.
4) affinity_mask = 0x0, online mask = 0x7. CPU 1 is going down.
this_count is incremented, as the affinity mask is 0.
P.
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