Re: [PATCH 2.6.12-rc5-mm2] [sched] add allowed CPUs check into find_idlest_group()

["M.Baris Demiray" <baris@labristeknoloji.com>]

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Nick Piggin wrote:
> M.Baris Demiray wrote:
 > [...]
>>
>> But, isn't it required for us to be allowed to run on _every_
>> CPU in that group. If we take intersection and continue if
>> that's not empty, then there could be CPUs in group that are
>> not allowed. Since any CPU then can be the idlest in that
>> group we can be assigned to a CPU that is not allowed.
>> Missing something?
>>
> 
> That should be OK. We basically aren't too interested in
> exactly which CPU it should go to, but just that it should
> go to that group.
> 
> If the group is determined to be the idlest, and there is
> a CPU that can run the task, then that's all we need.

OK. And also I missed the point that you requested a second check
in find_idlest_cpu() which'll prevent an assignment to an unallowed
CPU. That will solve the problem.

 > [...]
>>
>> Meanwhile, what is the problem with that patch? Not traversing
>> the CPUs correctly or continue;ing is wrong?
>>
>>     for_each_cpu_mask(i, group->cpumask) {
>>         if (!cpu_isset(i, p->cpus_allowed))
>>             continue;
>>     }
>>
> 
> In Linux, the for_* macros actually *are* for loops. So that is
> that loop that your continue continues, and seeing as it is at
> the end of that for loop, it does nothing.

Argh. I'll look at these.

Thanks Nick.

> Thanks,
> Nick
> 

-- 
"You have to understand, most of these people are not ready to be
unplugged. And many of them are no inert, so hopelessly dependent
on the system, that they will fight to protect it."
                                                         Morpheus

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