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 _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
