powerd and increase in energy need

[John]

>my zfs nas has an Asus p5e motherboard (x38 chip) and an intel q9300 (quad
>core 2,5Ghz) processor with all the energy save setting enabled in the
>bios. Today I connected the power cord to a voltcraft energy meter to see
>how much energy the whole system needs in idle mode.
>
>I found out that with powerd running the cpu get clocked down to 499 mhz
>with is nice. The funny thing is that this doesn't decrease the amount of
>watts the machine need. 2,5ghz or 499mhz doen't matter at all. It gets even
>funnier. With powerd running the systems actually needs 4 watts more then
>without powerd running.
>
>Isn't the whole point of powerd to to decease the energy needs of a
>machine? or is it utterly broken with this cpu generation?

Powerd does decrease energy on my more modern hardware. This machine is used
for backups and is idle much of the time. It runs Freebsd 8.3-Prerelease with
the turbo-boost patch on an i5-650 in an intel DH55HC motherboard.

The following power measurements were made with a Kill-A-Watt meter.

91w while doing a compile, dev.cpu.0.freq: 3193 (turbo boost enabled)
81w compile complete, disks quiet, top reports between 99.9 and 100% idle
	dev.cpu.0.freq: 3193 
71w idle for several seconds, powerd running in hiadaptive mode,
	dev.cpu.0.freq: 1197


sysctl dev.cpu |grep cx
dev.cpu.0.cx_supported: C1/3 C2/205 C3/245
dev.cpu.0.cx_lowest: C2
dev.cpu.0.cx_usage: 100.00% 0.00% 0.00% last 259us

sysctl dev.cpu |grep freq                                           ~
dev.cpu.0.freq: 1197
dev.cpu.0.freq_levels: 3193/9875 3192/9125 3059/8250 2926/7500 2793/6875 2660/6250 2527/5750 2394/5250 2261/4750 1197/2750

/etc/rc.conf
powerd_flags="-n hadp"
performance_cx_lowest="C2"
economy_cx_lowest="C2"
performance_cpu_freq="HIGH"

John Theus
TheUs Group
TheUsGroup.com