Re: false nr_running check in load balance?

[Lei Wen]

Hi Paul,

On Tue, Aug 13, 2013 at 4:08 PM, Paul Turner <pjt@xxxxxxxxxx> wrote:
> On Tue, Aug 13, 2013 at 12:38 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> On Tue, Aug 13, 2013 at 12:45:12PM +0800, Lei Wen wrote:
>>> > Not quite right; I think you need busiest->cfs.h_nr_running.
>>> > cfs.nr_running is the number of entries running in this 'group'. If
>>> > you've got nested groups like:
>>> >
>>> >  'root'
>>> >    \
>>> >    'A'
>>> >    / \
>>> >   t1 t2
>>> >
>>> > root.nr_running := 1 'A', even though you've got multiple running tasks.
>>> >
>>>
>>> You're absolutely right for this. :)
>>> I miss it for not considering the group case...
>>>
>>> Then do you think it is necessary to do below change in load_balance() code?
>>>  -       if (busiest->nr_running > 1) {
>>>  +       if (busiest->cfs.h_nr_running > 1) {
>>>
>>
>> Yes I think that would be fine.
>
> If we pivot to use h_nr_running we should probably also update
> call-sites such as cpu_load_avg_per_task() for consistency.

I didn't find cpu_load_avg_per_task in the latest linux git...
Is it a new patch pending while not being submitted?

Thanks,
Lei
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