[tesla-dev] [powertop bug]: need powertop support to report "turbo mode" frequency - report by jim britton

[Mark Haywood]

Li, Aubrey wrote:
> Firstly, many thanks to report this bug, :-)
>
> Before we setup powertop bug track system on defect.opensolaris.org,
> can we report bug to the mailing list first?
>
> my comments about this bug:
>
> This is a very good raise-up, really. But I think it'd better to place
> this bug into Todo list.
> Currently kernel doesn't support any mechanism to obtain the frequency
> in the "turbo mode".
> So, powertop can't report any related info. Actually hardware feedback
> machanism exists on
> the processor, We need to enable it.
>   

It is true that the APERF/MPERF hardware feedback mechanism can help to 
identify that a processor has been in "turbo mode". But unless I'm 
mistaken there is no guarantee that when the processor is in Turbo Mode 
that APERF/MPERF will catch it. Among other things, it would depend upon 
your polling interval - which currently is pretty long.

What exactly would powertop report about 'turbo mode'? Amount of time 
spent in "turbo mode"? I think a metric like that is bound to be 
incorrect given the current hardware support isn't it?
> Thanks,
> -Aubrey
>
>
>