Re: Postgres refusing to use >1 core

Aren Cambre <aren@arencambre.com> wrote:

>>>    - Core i7 processor--4 physical cores, but OS sees 8 cores
>>>    via hyper-threading
>>
>> Most benchmarks I've seen comparing hyper-threading show that
>> PostgreSQL performs better if you don't try to convince it that
>> one core is actually two different cores.  With HT on, you tend
>> to see context switching storms, and performance suffers.
>>
>> > At first, the app pounds all 8 cores.
>>
>> You really shouldn't let the marketers get to you like that.  You
>> have four cores, not eight.
>>
>
> I agree. :-) Just trying to express things as my OS sees and
> reports on them.

Your OS won't *see* eight processors if you turn of HT.  :-)

I'm going to pursue this digression just a little further, because
it probably will be biting you sooner or later.  We make sure to
configure the BIOS on our database servers to turn off
hyperthreading.  It really can make a big difference in performance.

-Kevin