Bulldozer determines frequency by power draw?

[Althernai]

There is a curious statement in this blog:

AMD Turbo CORE is deterministic, governed by power draw, not temperature as other competing products are. This means that even in warmer climates you’ll be able to take advantage of that extra headroom if you choose. This helps ensure a max frequency is workload dependent, making it more consistent and repeatable.

How does this work? Being deterministic is nice, but surely it has to down-clock if the temperature is getting out of hand? And shouldn't the power draw be constant at any given frequency? Unless of course the temperature change somehow influences it and thus it is still governed by temperature, just not directly.

[codedivine]

There is a curious statement in this blog:

AMD Turbo CORE is deterministic, governed by power draw, not temperature as other competing products are. This means that even in warmer climates you’ll be able to take advantage of that extra headroom if you choose. This helps ensure a max frequency is workload dependent, making it more consistent and repeatable.

How does this work? Being deterministic is nice, but surely it has to down-clock if the temperature is getting out of hand? And shouldn't the power draw be constant at any given frequency? Unless of course the temperature change somehow influences it and thus it is still governed by temperature, just not directly.

No, power draw is not only dependent on frequency and voltage, but also workload dependent as various parts of the processor may be switched off depending on the workload. Llano is known to have a set of digital sensors that AMD claims gives it an ability to estimate power draw on various units within 2% (updated every microsecond or so I believe) and I would expect Bulldozer to have the same technology.

[Althernai]

Thanks. I think I get it now: if given a workload that does not stress certain parts of the processor, it will turn them off and Turbo up within the thermal budget cleared by them. Of course, if that is how it works, then given a stress test that uses the entire processor, it will not Turbo at all.

[morphine]

Not necessarily. They may have a additional rule beyond that saying something like "if the temperature is under 90ºC, work at 120%".

[JF-AMD]

Turbo is based on power draw, not temperature. That allows the system to have more consistent turbo results.