N100 PL1 PL2 power limit testing

Limit intel turbo boost

If the aim is to run some Intel processors as efficient as possible, changing the power limit won't necessarily get it into the efficient frequency for single core loads.

For that it's necessary to set a maximum turbo frequency, this can be done like this:
for freq in /sys/devices/system/cpu/cpufreq/*/scaling_max_freq; do echo 3000000 > $freq; cat $freq; done

The default for N100 is 3.4 GHz which it will only boost to for a single core.
The following testing was done at PL1/PL2 at 15W. (i wouldn't recommend lowering PL1/PL2 below 14 W for efficiency unless you have issues with cooling)
Single core wall power draw for `stress-ng -c 1` stressing a single core:

max_freq    pWallSingle     geeks   geekm       geekl
2.0         7.8
2.2         8.2             839     2495        https://browser.geekbench.com/v6/cpu/9022108
2.4         8.9
2.6         9.5             983     2674        https://browser.geekbench.com/v6/cpu/9021962
2.8         10.2
3.0         11.0            1124    2686        https://browser.geekbench.com/v6/cpu/9021838
3.2         12.1
3.4         13.5            1224    2662        https://browser.geekbench.com/v6/cpu/9021556

I'm quite ok if it's not the fastest single thread performer, thus i'll just use 3.0 GHz max freq.
Those 400 MHz less save 1.5 W during single threaded workloads.
For multi-threaded stuff the power limit described below is the relevant figure.
15 W is a pretty reasonable number to run really and the default for most N100 mini pcs.
But it's also reasonable to run 16 or 17 W to get some more performance.

For a permanent solution you could use a crontab:
run: crontab -e
insert this line:
@reboot /usr/bin/bash -c 'for freq in /sys/devices/system/cpu/cpufreq/*/scaling_max_freq; do echo 3000000 > $freq; cat $freq; done'

N100 power limit testing

PL1 and PL2 are just set to the same number for simplicity.
pWallSF is the power draw from mains.
geeks / geekm are the geekbench6 single / multicore scores


PL1/2   pWallSF StockfishScores             geeks   geekm   geekl
10      11.5    1604841,1582075,1788214     967     1842    https://browser.geekbench.com/v6/cpu/9003729
11.625  13.2    1924550,1925746,1893007     1086    2180    https://browser.geekbench.com/v6/cpu/9005510
13.375  15.0    2021293,2090408,2105400     1175    2480    https://browser.geekbench.com/v6/cpu/9005710
15      16.5    2309462,2327378,2193946     1229    2663    https://browser.geekbench.com/v6/cpu/9007153
16.625  18.3    2757442,2408745,2382714     1252    2830    https://browser.geekbench.com/v6/cpu/9008143
18.375  20.0    2985179,2463419,2493028     1251    2947    https://browser.geekbench.com/v6/cpu/9014086
20      21.7    2582110,2876978,2788260     1251    3044    https://browser.geekbench.com/v6/cpu/9014752