Is the C3 possible with SMP?

[Alexander Motin]

Alexandre "Sunny" Kovalenko wrote:
> When laptop is moving around with me, all USB modules are unloaded and I

I will try to unload USB later today.

> get about 4 hours of battery life with wireless on, admittedly on the
> light usage (reading/writing E-mails, browsing web, typing up occasional
> document). I consider this good for 4.4lbs (<2kg) laptop.

I have a bit more then 3 hours at the same weight. Which CPU, video and
chipset do you have?

> OK, so we have C3. Is this the machine you see no difference in power
> consumption between C3 and no C3? How did you measure it?

Yes. I am using `acpiconf -i 0`. I have no way to measure AC power and I
am not sure in precision of such measurements due to limited AC power
supply effectiveness.

I have some doubts that C3 on only one of two cores could give much
benefit. I have already lowered frequency and voltage via EST by powerd.
I have turned off most of CPU clocks with Core2Duo C2E state. So,
according to what I have read, now only APICs and bus controller are
active. As soon as I see timer interrupt on cpu1 it's APIC is not
sleeping. Bus controller is shared by cores, so it can't be disabled
until at least one core is active.

-- 
Alexander Motin