CPU dynamic scaling on NetBSD

I know about estd for a while, that daemon “dynamically sets the CPU-frequency on Enhanced SpeedStep, PowerNow, and APCI P-States-enabled CPUs depending on current cpu-utilization” (manpage excerpt). Thing is, I’ve never seen any CPU changing from its current speed while monitoring the machdep.powernow.frequency.current sysctl. In order to understand what was happening, I started estd with the -o flag, which outputs the CPU-frequencies as they are set. I then realized that the “ligh watermark percentage” and “low watermark percentage” default values were way too high (respectively 40 and 80) and were never reached, so the CPU speed was never changed.