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[Alex Deucher]

On Fri, Feb 25, 2011 at 6:03 PM, Phillip Susi <psusi at cfl.rr.com> wrote:
> On 02/25/2011 03:38 PM, Alex Deucher wrote:
>>
>> The CP firmware has nothing to do with the temperature.  The CP
>> firmware is just a packet parser for reading in command buffers and
>> programming the register backbone.  Just alike a CPU, the GPU runs at
>> whatever speed it's clock is set to.  You can manually force lower
>> power states using sysfs.  See the power management section of this
>> page:
>> http://wiki.x.org/wiki/RadeonFeature
>
> I have tried writing low to power_profile and it seems to make little to no
> difference.  A cpu executing a tight loop busy waiting for something to do
> wastes a lot more power than one that has executed a HLT instruction, or
> used even better stop states to gate off clocks that are not needed.  It
> seems to me that when there is nothing for the GPU to do, it also should
> stop executing instructions and gate off any unneeded clocks.
>

It only executes instructions when you tell it to; it's not running
constantly.  At the moment clock gating support is not implemented on
newer asics.

Alex