[Arm-netbook] Power Figures (Armada vs Atom)

Gordan Bobic gordan at bobich.net
Mon May 21 09:20:59 BST 2012

On 05/20/2012 06:53 PM, Dr. David Alan Gilbert wrote:
> * Gordan Bobic (gordan at bobich.net) wrote:
>> For entertainment purposes, I thought I'd share.
>> PoE with PoE->12VDC splitter, idle in both cases:
>> Advancetech Atom N450 uATX board: 18.6W
>> (occassionally trips the 30W class 3 PoE limit during POST)
>> Compulab SBC-A510, Marvell Armada 510: 9.2W
>> No contest. Granted, 9.2W is still a lot (SheevaPlug draws about 7W from
>> AC flat out), but it's still a hell of a lot better than 18.6.
> That's a good number for idle;

For Atom - maybe. For an ARM, it's pretty attrocious. My AC100 idles at 
6W without CPU frequency/voltage scaling, and that includes the TFT 
screen which is responsible for about half of those 6W.

> have you tried using something like
> powertop to tune them?

I did for the Atom - it is as good as it gets at 18.6W.
Haven't gotten around to it for the Armada yet.

> How about doign the same comparison when doing some comparable work
>   (both say playing audio/video from approximately the same source
> and at same res)?

These are headless servers. The closest to a load test I could arrange 
for is something like an in-RAM SHA512 loop.


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