Re: [PATCH 0/2] RFC: CPU frequency max as PM QoS param

[Antti Miettinen <amiettinen@nvidia.com>]

To the lists too..

On 02/27/2012 04:49 PM, Kevin Hilman wrote:
> mark gross <markgross@thegnar.org> writes:
>
>  >> Current QoS settings could be thought of as performance constraints
>  >> too. It's just that they determine minimum performance. Adding
>  >> constraints for maxium performance is not a big stretch in my mind.
>  >
>  > Its not a big stretch to me either. I just think its a bit of a hack
>  > and there is a bigger more interesting issue getting overlooked.
>  >
>  > Lastly why not simply make cpufreq thermal aware and talk directly to
>  > it if you even need too?
>
> In fact, making a thermal framework "cooling device" that talks directly
> to CPUfreq is already what's being done by the Linaro PMWG folks.
>
> The problem is that CPUfreq only controls the CPU frequency.
>
> There are other devices that could be scaled back to reduce heat as well
> (DSP, and especially GPU), so having a more generic per-device
> constraint interface that can cap the frequency for *any* scalable
> device is a better framework IMO.
>
> It just so happens that pm_qos is already a good per-device constraint
> framework and can easily modified to cap performance as well as request
> a minimum performance.
>
> Kevin
>