Re: Re: [PATCH] base: arch_topology: Use policy->max to calculate freq_factor

[Lukasz Luba]

Hi Rafael,

On 11/16/21 7:05 PM, Rafael J. Wysocki wrote:
> On Mon, Nov 15, 2021 at 9:10 PM Thara Gopinath
> <thara.gopinath@xxxxxxxxxx> wrote:
> > cpuinfo.max_freq can reflect boost frequency if enabled during boot.  Since
> > we don't consider boost frequencies while calculating cpu capacities, use
> > policy->max to populate the freq_factor during boot up.
>
> I'm not sure about this.  schedutil uses cpuinfo.max_freq as the max frequency.

Agree it's tricky how we treat the boost frequencies and also combine
them with thermal pressure.
We probably would have consider these design bits:
1. Should thermal pressure include boost frequency?
2. Should max capacity 1024 be a boost frequency so scheduler
   would see it explicitly?
- if no, then schedutil could still request boost freq thanks to
  map_util_perf() where we add 25% to the util and then
  map_util_freq() would return a boost freq when util was > 1024


I can see in schedutil only one place when cpuinfo.max_freq is used:
get_next_freq(). If the value stored in there is a boost,
then don't we get a higher freq value for the same util?