powerd on 8.0, is it considered safe?

Dan Naumov dan.naumov at gmail.com
Mon Mar 8 12:01:49 UTC 2010

Okay, now I am baffled.

Up until this point, I wasn't using powerd on this new Atom D510
system. I ran sysctl and noticed that dev.cpu.0.freq: is actually 1249
and doesn't change no matter what kind of load the system is under. If
I boot to BIOS, under BIOS CPU is shown as 1,66 Ghz. Okayy... I guess
this explains why my buildworld and buildkernel took over 5 hours if
by default, it gets stuck at 1249 Mhz for no obvious reason. I enabled
powerd and now according to dev.cpu.0.freq:, the system is permanently
stuck at 1666 Mhz, regardless of whether the system is under load or

atombsd# uname -a
FreeBSD atombsd.localdomain 8.0-RELEASE-p2 FreeBSD 8.0-RELEASE-p2 #0:
Tue Jan  5 21:11:58 UTC 2010
root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64

atombsd# kenv | grep smbios.planar.product

atombsd# sysctl dev.cpu dev.est dev.cpufreq dev.p4tcc debug.cpufreq
dev.cpu.0.%desc: ACPI CPU
dev.cpu.0.%driver: cpu
dev.cpu.0.%location: handle=\_PR_.P001
dev.cpu.0.%pnpinfo: _HID=none _UID=0
dev.cpu.0.%parent: acpi0
dev.cpu.0.freq: 1666
dev.cpu.0.freq_levels: 1666/-1 1457/-1 1249/-1 1041/-1 833/-1 624/-1
416/-1 208/-1
dev.cpu.0.cx_supported: C1/0
dev.cpu.0.cx_lowest: C1
dev.cpu.0.cx_usage: 100.00% last 500us
dev.cpu.1.%desc: ACPI CPU
dev.cpu.1.%driver: cpu
dev.cpu.1.%location: handle=\_PR_.P002
dev.cpu.1.%pnpinfo: _HID=none _UID=0
dev.cpu.1.%parent: acpi0
dev.cpu.1.cx_supported: C1/0
dev.cpu.1.cx_lowest: C1
dev.cpu.1.cx_usage: 100.00% last 500us
dev.cpu.2.%desc: ACPI CPU
dev.cpu.2.%driver: cpu
dev.cpu.2.%location: handle=\_PR_.P003
dev.cpu.2.%pnpinfo: _HID=none _UID=0
dev.cpu.2.%parent: acpi0
dev.cpu.2.cx_supported: C1/0
dev.cpu.2.cx_lowest: C1
dev.cpu.2.cx_usage: 100.00% last 500us
dev.cpu.3.%desc: ACPI CPU
dev.cpu.3.%driver: cpu
dev.cpu.3.%location: handle=\_PR_.P004
dev.cpu.3.%pnpinfo: _HID=none _UID=0
dev.cpu.3.%parent: acpi0
dev.cpu.3.cx_supported: C1/0
dev.cpu.3.cx_lowest: C1
dev.cpu.3.cx_usage: 100.00% last 500us
sysctl: unknown oid 'dev.est'

Right. So how do I investigate why does the CPU get stuck at 1249 Mhz
after boot by default when not using powerd and why it gets stuck at
1666 Mhz with powerd enabled and doesn't scale back down when IDLE?
Out of curiosity, I stopped powerd but the CPU remained at 1666 Mhz.

- Sincerely,
Dan Naumov

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