powerd forgets top CPU frequency ?

From: Poul-Henning Kamp <phk_at_phk.freebsd.dk>
Date: Sat, 24 Aug 2024 17:06:21 UTC
On T14s thinkpad running:

	FreeBSD critter.freebsd.dk 15.0-CURRENT FreeBSD 15.0-CURRENT #7 main-n271455-a1740cb93639-dirty: Thu Aug  1 09:45:40 UTC 2024     root@critter.freebsd.dk:/critter/obj/critter/FreeBSD/src/amd64.amd64/sys/GENERIC-NODEBUG amd64

When I run two 100% CPU loaded processes, the machine gradually gets slower and slower, until eventually it limps along at 500-ish MHz rates.

Killing powerd and starting it again seems to bring the machine back to full speed (for some time).

Looking at the powerd -v output, my gut feeling is that powerd sometimes looses track of what the (current) top frequency is and thus gradually drags the machine slower or slower...

I have had a faint feeling for some time that this machine runs significantly faster after a reboot, but I have no observations to support that.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.