Re: [PATCHv3 2/2] powerpc: implement arch_scale_smt_power for Power7

Joel Schopp
2010-01-29T16:26:30Z

Gabriel Paubert wrote:
> On Thu, Jan 28, 2010 at 05:20:55PM -0600, Joel Schopp wrote:
>
>> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads
>> there is performance benefit to idling the higher numbered threads in
>> the core.
>>
>>
>
> Really 2, 3, or 4? When you have 4 idle threads out of 4, performance
> becomes a minor concern, no? ;-)
>
> Gabriel
>
Yes, but going from 4 idle to 3 idle you want to keep the slanted
weights. If you ignored 4 you'd place wrong and then correct it after
the fact.