Re: [Xenomai] [PATCH] ipipe: x86: Populate vector_irq for all dispatched vectors

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-09-19 16:46, Gilles Chanteperdrix wrote:
> 
> Jan Kiszka wrote:
>> On 2012-09-19 16:28, Gilles Chanteperdrix wrote:
>>>
>>> Jan Kiszka wrote:
>>>>  	for (vector = 0; vector < NR_VECTORS; ++vector) {
>>>> +		/* I-pipe requires initialized vector_irq for system vectors */
>>>> +		if (test_bit(vector, used_vectors))
>>>> +			continue;
>>>>  		irq = per_cpu(vector_irq, cpu)[vector];
>>>>  		if (irq < 0)
>>>>  			continue;
>>>
>>> This looks wrong to me: you are skipping a part a code that was setting
>>> to
>>> -1 vectors that were allocated but not used on this cpu.
>>
>> I'm skipping only used_vectors, i.e system vectors. They will be set up
>> for I-pipe for that well-known reason. I'm no longer skipping to clear
>> IRQ vectors that are not used on the current CPU (!cpumask_test_cpu(cpu,
>> cfg->domain)). That is what was missing in both approaches so far.
>>
>> Note: vector_free = (vector_irq == -1) && !used_vector
> 
> Let us go back to the obvious loop:
> 
>>         for (vector = 0; vector < first_system_vector; ++vector) {
>>                 if (vector == IRQ_MOVE_CLEANUP_VECTOR)
>>                         continue;
>>
>>                 irq = per_cpu(vector_irq, cpu)[vector];
>>                 if (irq < 0)
>>                         continue;
>>
>>                 cfg = irq_cfg(irq);
>>                 if (!cpumask_test_cpu(cpu, cfg->domain))
>>                         per_cpu(vector_irq, cpu)[vector] = -1;
>>         }
> 
>>From what I understand, this function is called when a CPU is started,
> so, for instance, with hotplug cpu, on a system that has been running
> for days and so had a lot of time to allocate a lot of vectors.
> 
> Now, some of these vectors are known not to be needed on the cpu we
> are currently starting. What this loop does, is for such vectors, to
> set the vector_irq entry on the cpu we are currently starting to -1.
> 
> Now, such vectors will certainly have the used_vectors bit to 1.

used_vectors should be called "used_for_system_vector".

Jan

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