Re: [tip:sched/core] sched/numa: Rewrite the CONFIG_NUMA sched domain support

[Alex Shi <alex.shi@intel.com>]

On 06/06/2012 05:15 PM, Peter Zijlstra wrote:

> On Wed, 2012-06-06 at 15:43 +0800, Alex Shi wrote:
>>> +       /*
>>> +        * O(nr_nodes^2) deduplicating selection sort -- in order to find the
>>> +        * unique distances in the node_distance() table.
>>> +        *
>>> +        * Assumes node_distance(0,j) includes all distances in
>>> +        * node_distance(i,j) in order to avoid cubic time.
>>
>> Curious for other platforms node_distance number, actually, this
>> assumption is right for what I saw Intel platforms. but it is not
>> match acpispec50.pdf:
>>
>> Table 6-152 Example Relative Distances Between Proximity Domains
>> Proximity Domain 0 1 2 3
>> 0 10 15 20 18
>> 1 15 10 16 24
>> 2 20 16 10 12
>> 3 18 24 12 10
> 
> Yes I know its allowed, I just haven't seen it in practice.


I see. Thanks.

> 
> I've got a patch that validates this assumption if you boot with
> "sched_debug". If we ever run into such a setup we might need to fix
> this -- it shouldn't be too hard, just expensive.


Sure.