[ltp] X60 power consumption

[Richard Neill]

Nils Faerber wrote:

> It is a very annoying topic though. I never had to worry about this
> stuff and manually setting it to something with my X31...

Was the X31 better, or was it just that the X31 didn't have the scope to 
save as much power?

>> Very useful. Am I correct in assuming that laptop-mode is irrelevant if
>> I have an SSD?
> 
> Well - also accesses to the SSD will cause bus activities and CPU
> activity. So doing nothing also saves power. Not much of course.

Presumably without the cost of spinups, there's no great advantage to 
grouping writes - we're not avoiding activity, just postponing it.

> 
>>> Using this I can get about 9 to 9.5W with WiFi enabled which is IMHO OK.
>>> (And no need to unload the uhci-hcd module...)
>>>
>>> It is still way too much and the fan still spins almost all the time but
>>> a lot of the power now goes into the chipset and graphics and there is
>>> little we can do there - at least from what I know.
>> I'm still at 11W here.
> 
> This is strange.
> Let's recheck...hmm... today here in the office I also get pretty
> exactly 11W with WiFi (though I cannot dim the backlight to minimum
> again :( and about 10W without WiFi. Strange.

OK. I'm sure it's possible to do better. The claimed 7 hour life in XP 
implies about 6 Watts!

> 
>> I did get the fan to stop, very useful to simply install tp-fand, and
>> set the thresholds to 65 degrees. This is too hot for lap-top use, but
>> fine for a table.
>> http://www.gambitchess.org/mediawiki/index.php/ThinkPad_Fan_Control#Ubuntu_8.04_.2F_8.10_.2F_9.04
> 
> I am not in favour of this, sorry. If my machine gets hotter that the
> default threshold of ~45°C it shall toggle the fan. But it should not
> get that hot in the first place! Heat means energy and this comes from
> my battery! So less heat, less power consumption, longer battery life.

I mostly agree. But when the machine is on AC and on a table, I prefer 
silence. If the machine is very busy doing something useful, then why 
drive both the CPU and the fan, when we could merely drive the CPU. 
Also, 45 degrees is very very conservative.


> 
>>> If you have it installed watch the powertop output and see if your CPU
>>> stays in C4 most of the time. If not, find the course.
>> Aha. I am almost always in C3 (at 1GHz) but never see C4. It's not even
>> shown as an possibility in powertop. Any ideas why this could be?
> 
> Oh ho ho - my bad, I did not recheck that, it is C3 of course, not C4.
> The CPU does support C4 but the BIOS does not. So C3 is the lowest we
> see in Linux.

That's useful to know. It will save me a lot of time trying to find out 
why I can't get C4!  I'm puzzled why it's not in the BIOS - especially 
given that I've updated to the latest version.

Richard


P.S. I tried an upgrade to karmic. Am reverting to Jaunty. Don't do it 
yet - there are no major advances, but it does break suspend to ram.