RFC: Simplfying hyperthreading distinctions

[Harrison Grundy]

On 03/22/15 02:07, Gary Jennejohn wrote:
> On Sat, 21 Mar 2015 21:43:35 +0200
> Ivan Klymenko <fidaj at ukr.net> wrote:
> 
>> __ Sat, 21 Mar 2015 12:24:20 -0700
>> Alfred Perlstein <alfred at freebsd.org> __________:
>>
>>> John,
>>>
>>> Just a quick note on this, hopefully it's not too off-topic...
>>>
>>> We need to detect if HTT or SMT is enabled, right now there are no 
>>> sysctl nodes to detect this and instead we have to parse xml out of
>>> the scheduler...
>>>
>>> Does it make sense to have a basic sysctl tree for this?
>>>
>>> hw.cpu.threading.smt=0
>>> hw.cpu.threading.htt=0
>>>
>>> or something?
>>>
>>
>> I am sorry that I interfere
>> Why then not use kern.smp.topology for this purpose?
>>
> 
> Because it's only present in the ULE scheduler, BSD doesn't
> have it.
> 

Extracting topology detection out of the scheduler and finalizing that
API may be a good idea anyway, given the NUMA work going on elsewhere.
Things besides the scheduler can benefit from the information, and it'll
simplify the scheduler a bit.

Any thoughts on handling it that way?

--- Harrison