Fan control for PowerMac7_3 (#3)
paulus at samba.org
Sun Oct 17 10:53:21 EST 2004
H. Peter Anvin writes:
> It's the backside fan that oscillates; backside_fan_pwm varies between
> 30 and 100 in what is pretty much a squarewave. See attached graph (and
> note how the other fans vary with workload.)
The sharp rises look like the code thinks it gets into an
over-temperature situation and turns the fans on full blast. It could
be worth putting some printks in the overtemp code.
> I probably need to write a "power virus" program for the G5 to really
> test out the high end (a power virus is a program which keeps the chip
> running as hard as it can; generally keep all pipelines stuffed.)
Hmmm, I should see if I can dig such a thing out of somewhere in IBM.
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