Re: [PATCH] Avoid mask based num_possible_cpus and num_online_cpus

[Venki Pallipadi]

On Fri, Jan 20, 2012 at 3:45 PM, KOSAKI Motohiro
<kosaki.motohiro@xxxxxxxxx> wrote:
>>>> +int nr_online_cpus __read_mostly;
>>>> +EXPORT_SYMBOL(nr_online_cpus);
>>>> +
>>>>  void set_cpu_possible(unsigned int cpu, bool possible)
>>>>  {
>>>>       if (possible)
>>>
>>>
>>> Did you forget to add:
>>>
>>>        nr_possible_cpus = cpumask_weight(cpu_possible_mask);
>>>
>>> inside set_cpu_possible() ?
>>
>> No. That was intentional as I have that coupled with nr_cpu_ids and
>> set once after all the bits are set in setup_nr_cpu_ids() instead of
>> doing for each bit set.
>
> But, Srivatsa's way seems more safer, no? Is there any advantage to make couple
> with nr_cpu_ids?

I think it is a tradeoff between safer and cleaner :). infact, that's
how I had coded the patch first. But, then I changed it to be in sync
with nr_cpu_ids as it seemed a bit cleaner (and also to make sure 2048
CPU guys won't come after me for doing the mask calculation 2048 times
during the boot).
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