kern.hz="100" stops high-pitched whine

cpghost cpghost at
Sun Jul 1 11:10:30 UTC 2007

I'm using fan-less Soekris (266 MHz) and EPIA (500 MHz)
boards with -STABLE. Those boards have been emitting a
very high pitched annoying whine, similar to a dog
whistle. Not everyone I asked could hear it, but I was,
and it was driving me crazy for months.

This whine stopped entirely the moment I put
kern.hz="100" in /boot/loader.conf and rebooted.
Quite relieving!

Are there any reasons NOT changing kern.hz from the
default 1000 back to 100? With my typical mix of
desktop apps (EPIA) and networking / server (Soekris),
everything seems to be running just as smoothly with
100 Hz than with 1000 Hz (testing now for two weeks
without problems). Even playing videos with mplayer
on the EPIA doesn't look different in any way.

Is it okay to stay with 100 Hz with this type of
low-speed CPU/boards? Or are there some compelling
reasons not to?


Cordula's Web.

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