Hi!
> > let me give you a real world example then, and the numbers I'm using are
> > ballpark the same as you'll find in a (mobile) core 2 duo datasheet, I
> > just rounded them a little so that the math works out nice.
> >
> > power at full speed: 34W
> > power at half speed: 24W
> > power at idle: 1W
>
> I have usually seen different numbers, for example:
>
> http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/30430.pdf
Trust Arjan, modern cpus work as he describes.
> Although this paper speaks about thermal design power instead of power
> consumption, i suppose that it should be roughly equal.
>
> For example Athlon 64 3700 (ADA3700AEP5AR):
>
> 2.4 GHz, 1.5 V -> 89 W
> 2.2 GHz, 1.4 V -> 72 W
> 2.0 GHz, 1.3 V -> 53 W
> 1.8 GHz, 1.2 V -> 39 W
> 1.0 GHz, 1.1 V -> 22 W
I guess that means athlon 64 is 'old'.
> Even my measurement on PC (Athlon X2, VIA K8T890) of complete PC power
> consumption shows that it is more efficient to be busy for 2 time units
> on 1 GHz than be busy for 1 time unit and be idle for 1 time unit
> on 2 GHz.
>
> 1 GHz:
> both cores idle: 48 W
> one core busy: 57 W
> two cores busy: 66 W
2 sec decoding video at both cores: 132J
> 2 GHz:
> both cores idle: 54 W
> one core busy: 78 W
> two cores busy: 95 W
1 sec decode @ 2GHz + 1 sec idle @ 1GHz: 143J
So even on your hw difference is not too big... and take a look at
numbers from core2duo.
Actually...
4 sec decode @ 1 core @ 1GHz: 57*4=228J
1 sec decode @ 2 cores @ 2GHz, then idle: 95 + 48*3 = 142+95 = 235J...
Ok, so it is still win, but even smaller one..
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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