[ltp] The zen of power saving, still 21.4W on Thinpad Z61p :(

[Marc MERLIN]

[4 replies, see below]

First, Ted, I tried your 2.6.24rc3 kernel and it didn't yield any
measureable improvements on my system (over my 2.6.22.15 noticks), even
with sata power save turned on by powertop 1.9.

On Fri, Dec 28, 2007 at 02:26:53PM -0500, Mike Kershaw wrote:
> > 9.5 - 10.5W with WLAN here (R51). ~13W is normal.
> >
> 
> The Nvidia based *61s idle MUCH higher than others.  20W is about
> normal.  

Thankfully, I have an ATI FireGL 5200, which I understand isn't as bad.

> Try the latest bios images - I noticed they seemed to let me
> save ~3W or so, so by dropping the brightness I can often get down to

I'll try and find one, and flash it, thanks.

On Fri, Dec 28, 2007 at 02:41:54PM -0500, Stephen Ryan wrote:
> fglrx is a big chunk of your problem.
> 
> I had similar problems with my T60p and wrote them up:
> 
> http://www.beardendesigns.com/blogs/permalink/25
> 
> The fglrx driver was responsible for about 1/3 of my idle power usage,
> but consistently getting the power usage down has proven to be hard,
> especially since the vesa driver is somewhat lacking in performance
> and I end up switching back to fglrx.

I hadn't gotten around to that yet, but just did so. Found interesting
stuff.
Never mind the fact that the vesa driver didn't even want to do
1920x1200 (although I'm sure I could have coerced it :), the power
usage I got was oscillating between 16.9W and 20W with little input
from me (as opposed to 21.9W with fglrx + kernel module).

Then, I tried the fglrx X driver, but without the kernel module, and got
as low as 16.0W in full idle (although a typical usage with the fan
spinning was more around 18.5W)

On Fri, Dec 28, 2007 at 08:10:22PM +0100, Laurent Gilson wrote:
>> This prodded me to look into the humongous power usage of my Z61p some
>> more, and here are all the details I found, along with a plea for more
>> suggestions and help :)
>
> Does the CPU voltage-scaling work? Your CPU should switch to a lower
> voltage if a lower frequency is used. check 
> /sys/devices/system/cpu/cpu0/cpufreq/
> for more information.

I don't see anything to set the voltage on 2.6.22.15.
I actually wish I could shut down a CPU to save power (although I'm told
that the last person who try didn't save power), and run the other one
at 400Mhz when all I'm doing is reading a firefox browser page, or using
mutt, but I guess my CPUs won't let me do that.

gandalf:/sys/devices/system/cpu/cpu0/cpufreq#  for i in *; do echo $i;
cat $i; done
affected_cpus
0 1
cpuinfo_cur_freq
1000000
cpuinfo_max_freq
2000000
cpuinfo_min_freq
1000000
scaling_available_frequencies
2000000 1667000 1333000 1000000 
scaling_available_governors
userspace powersave ondemand conservative performance 
scaling_cur_freq
2000000
scaling_driver
centrino
scaling_governor
ondemand
scaling_max_freq
2000000
scaling_min_freq
1000000

> Try fixing the frequency at 1GHz. It will hurt performance... but you will
> not notice it in office. The > 600 switchs from 1GHz to 2GHz are a real 
> killer and should be avoided.

So, you mean this, right?
gandalf:/sys/devices/system/cpu/cpu0/cpufreq# echo 1000000 > scaling_max_freq

Sure, I can do that.
I didn't see any clear difference, though, I'm now at 16.0W to 18.5W
with fglrx driver in x.org but without the kernel driver.

That's better than before, for sure, and maybe all I can reasonably get
on this laptop.

Thanks for the replies,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/