Kernel functionality which replaced cpuspeed daemon thermal limits ?

[Daniel P. Berrange]

Back in Fedora 16, the cpuspeed daemon RPM was removed from the
repositories. To quote [1]

   "Fedora 16 kernel cpufreq stack now fully replaces CPUSpeed,
    effectively making the package obsolete."

There seems to be little clear documentation though on how to make use
of the cpufreq stack to do what cpuspeed was able todo. In particular I
have this setup:

  cpuspeed -i 10 -T 3 -t /sys/devices/virtual/thermal/thermal_zone1/temp 75000

Which lets the CPUs run at full speed when load demands, but if the
temperature exceeds 75C then cpuspeed throttles back regardless of
load to allow cooling.

AFAICT, none of the built-in kernel governors are able to express such
a policy. In particular the default ondemand governor is useless because
it will happily keep the CPU at full speed if there is load, even when
the temperature goes up to & beyond the critical thermal shutdown point.

Pretty much any parallel compile job will cause an emergency shutdown
in this way. Of course this is ultimately the fault of shitty Thinkpad
bios and/or cooling, but cpuspeed lets me cope with the hardware flaws.

Can anyone point out the kernel cpufreq config that I might have missed
to make it take into account thermal sensors when controlling CPU freq ?

If there is none, then I intend to re-submit cpuspeed for review and
inclusion in Fedora repos.

Regards,
Daniel

[1] https://fedoraproject.org/wiki/Fedora_16_Alpha_release_notes#What.27s_New_in_Fedora_16_Alpha
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