Some of you might know that the CPUs available these days adjust their frequency according to your computing needs, allowing you to save power by not using the maximum capacity of your processor if there isn’t such a need. Of course, this happens only when your operating system includes the software needed to access this feature. From Wikipedia we can find out what’s the impact of using the dynamic voltage and frequency scaling (DVFS) (named SpeedStep by Intel, respectively Cool’n’Quiet or PowerNow! by AMD):
The power consumed by a CPU with a capacitance C, running at frequency f and voltage V is approximately P = CV2f For a given processor, C is a fixed value. However, V and f can vary considerably.
Let’s take my desktop’s processor for example, an Intel Pentium 4 email@example.com GHz with Hyper Threading. Looking on the processor’s page info, one can find out that the voltage may vary between 1.200V and 1.3375V, while the frequency varies between 2.4 GHz and 3.0 GHz (if the processor wasn’t overclocked). With this data, the maximum power ratio that can be obtained is 3.10 (Pmax / Pmin). Now the maximum TDP (Thermal Design Power) for it is about 86 W. If the processor would be scaled at the minimum speed, it will drain only 27.74 W. That qualifies for a 58.26 Wh economy if the processor runs at the lowest speed for one hour, or if we put this in standard power consumption units, that would be 0.058 kWh. Of course, this represents ideal data because nobody buys a 3.0 GHz processor to use it only at a 2.4 GHz speed.
What has MicroMiser got to do with this?
Well, the guys from MiserWare, the company behind MicroMiser, implemented some super secret algorithms (I’m kidding, but these are their intellectual property) that can save power more efficiently than just by using your operating system’s power schemes, whether it’s Windows or Linux. Therefore, by using their daemon, you could save more power without having to do anything more than just install MicroMiser (which is free for personal use). On their FAQ page (where you can reach only after you register - for free again) they provide a nice power saving calculation based on their program. The conclusion is that MicroMiser can help you save between 10% and 30% more power, where the average is somewhere near 25%.
On my Ubuntu desktop I’ve started the MicroMiser daemon for about one hour and I am sure that my processor’s frequency hasn’t gone up to 3.0 GHz because I’ve only browsed some websites without annoying flash banners. If I check the log (on Linux MicroMiser doesn’t have a shiny GUI yet) I can see that I’ve saved about 0.01 kWh just by automatically launching this application without any other supplementary steps. Pretty cool, huh?
Launching the same application on Windows offers me a nice GUI where I can check the cumulative power savings or the ones predicted for one year, see different equivalents of the energy saved (including CO2 emissions), set the amount of money (in US dollars or in Pounds) per kWh and many others. Now really, was it so hard to write a GUI for Linux using GTK+ 2 or any other widget toolkit given the fact that we talk about power saving algorithms (far more complicated than some frames)?
Because I haven’t monitored my computers’ efficiency until now (at least not my desktop) I am not able to say if this application seems to do a better job than the already implemented power managers from different OSs. Still, judging by the fact that the product is offered for free for personal use but only with a license for companies I tend to believe that the algorithms behind it really do what advertised. Though I think that I can find out about this by installing the application on my laptop on which I reach to a maximum of 1h30’ of battery use after a full charge, using on demand processor speed (the laptop is 1yr and 3 months old and used daily for about 5 to 8 hours).
I really like the fact that MicroMiser’s CPU and memory necessities are unobservable both on Windows and on Linux. Even if I do like to use the terminal on Linux to do things faster, for this kind of application I would have really enjoyed a GUI instead of having to filter the output from the log files (even if it’s a one-liner command).
In order to be able to install the application you have to register here. Since MicroMiser is still in beta, every feedback you provide back to MiserWare will be useful. For Windows there’s an entry for that in the Programs’ menu. For Linux just open a terminal and type
sudo mw-feedback. Only some data regarding your system and the association of that system with your account will be sent over.
How much did you save?