powerd on 8.0, is it considered safe?

[Alexander Motin]

Alexander Motin wrote:
> Jeremy Chadwick wrote:
>> I should note that on RELENG_7, EIST/SpeedStep didn't appear to work
>> properly (cpufreq(4) driver reporting that the est piece wouldn't
>> attach), which historically (for me) has resulted in ACPI throttling
>> being done (which works).  Based on the sysctl output below, I believe
>> acpi_perf is in use, but I'm not 100% certain.  The man page doesn't
>> really disclose how to determine which driver is in use.
>>
>> The X7SBA system in question is below.  Be aware I limit the lowest
>> clock frequency to 1500MHz using debug.cpufreq.lowest="1500" in
>> /boot/loader.conf, which is why you don't see anything lower in
>> freq_levels.
>>
>> dev.est.0.freq_settings: 3000/35000 2667/28000 2333/22000 2000/16000
> 
> This is the real set of EIST supported levels.
> 
>> dev.cpu.0.freq_levels: 3000/35000 2667/28000 2333/22000 2041/19250
> 2000/16000 1750/14000 1500/12000
> 
> All the rest of these are throttling.
> 
> I would recommend you to disable it by setting:
> hint.p4tcc.0.disabled=1
> hint.acpi_throttle.0.disabled=1

> dev.cpu.1.cx_supported: C1/0 C2/85

And you may also enable C2 state, as your ACPI reports it, and it should
be safe now. To get maximum effect from it you may wish to reduce HZ.

-- 
Alexander Motin