[Bug 219213] powerd causing problems with ryzen

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219213

--- Comment #4 from SF <shitman71 at hotmail.com> ---
This made me think about it, my first example was good but still inherits
problems. This one is closer to final.

e.x.:
1 primary interval(long time period) to reset counters
1 secondary interval(short time period)to probe and count
1 counter for each p-state-limit and core

The primvary interval resets the counters to 0 each second.
The secondary interval probes every 10ms(?) the current load of each core and
increases the counter according to each p-state-limit by 1.

p-state 0 <20%
p-state 1 20%>
p-state 2 40$>
p-state 3 60%>
p-state 4 80%>

After 1 second it selects the cores with the highest reached limits.

Lets say core 1,2,3,4 did exceed 80%> and core 5,6,7,8,9,10,11,12,13,14,15,16
did only stay at max. 20%>. The 20%-Cores would outweight Core 1,2,3,4 and the
CPU will stay at a low p-state if they would taken into account, they dont get.
Only the CPU's with the max. reached p-state get counted together.

Core 1,2,3,4's counters get summarized and the p-state with the highest count
and priority gets selected.

The priority is needed because 80% spikes might occur less often then the
counter count something above 40% or 60%, this might cause staying at too low
p-state. The p-state 4 needs an higher priority because of it which means a
count of 20 on p-state 4 weights more then a count of 50 on p-state 0 or 2.

Finally there needs to be an timer to countdown the time for allowing
throttling down to a lower p-state if the previously high p-state didn't get
reached anymore.

P-state 4 didn't get reached anymore since 30 seconds and now the cpu is
allowed to power down to the new calculated value. If the calculations hit
p-state 4 again while the 30 seconds count down then the timer gets reset to 30
seconds and counts down again. This function can be optional and/or only kicks
in if the specified p-state is reached. This is for people running programs
with very much high-spikes and short periods of low load between it to avoid
clocking down and hitting the cap if the spike occurs.

Imho this is much more advanced then what powerd++ does and avoids some of the
problems mentioned. I think this is very interesting to servers.

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