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Boosting Battery Life For RISC Processors

Posted by ryuzaki0 on from the staying-unplugged-longer dept.

prostoalex writes "National Semiconductor and ARM Holdings will jointly develop the power management solution for RISC chips, that they estimate will improve battery life by 25-400%. The target date of the first sample product is Q2 2003." My old Tadpole laptop sure could have used this. I counted myself as lucky when I got a whole 45 minutes out of a battery.

4 of 113 comments (clear)

  1. Great move! by e8johan · · Score: 5, Insightful

    When developing portable devices the most limiting factor today is not processing resources, memory or anything such. It is simply the power source.

    Batteries of today are either too weak or too heavy. How ofter does one have to choose between a slim-line battery or an ultra-long life.

    There have been many suggestions for competing technologies such as fuelcells, harvesting of motion energy and solar cells to mention a few. But still, they have proven to be too expensive, large or have some other problem (such as not being ready for production use yet). Hopefully these one of these, or any other, portable power sources will make it possible to carry real computing power without having to carry a heavy battery pack.

    The solution today is to reduce the power usage. This can be done by shutting down parts of the clock trees in the CPUs, or by using Intel's PowerStep (i.e. two working speeds), or Transmetas's variable voltage and frequency technology, LongRun. As the article lacks technical details we can only guess about the techniques used behind the PowerWise solution. Also, the figures 25-75% efficiency gain is most probably measured under special conditions.

    But, in order to avoid sounding too negative, it seems like the industry has realized the problem and are working for a solution. I feel that most of today's solutions (power saving) are just a cure for the symptoms (bad battery time), not for the cause (bad battery technology).

    1. Re:Great move! by clickety6 · · Score: 4, Insightful

      Perhaps another approach would be to reduce requirements on the PC power by writing software that is less bloated and more efficient and is geared towards a portable solution. There really should be no need for my laptop to have a 1 Ghz chip just to run some word processing and spreadsheet software. Nor should the computer need 250 Megs of memory just to start up and run some windows. We should eb using nutcrackers to crack our nut, not a pile driver!

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    2. Re:Great move! by SmittyTheBold · · Score: 4, Insightful

      The solution today is to reduce the power usage. This can be done by shutting down parts of the clock trees in the CPUs, or by using Intel's PowerStep (i.e. two working speeds), or Transmetas's variable voltage and frequency technology, LongRun. ...or, by using an architecture that does not require as many useless (er...extra) transistors and is therefor more efficient to begin with. Witness the PowerPC, for example. In particular, the G3 is amazingly efficient in the desktop form.

      Compare, for example, the G4 at 11.5 million transistors, (I am not sure about the current G4e) and the P4 at 42 million (once again, this is an old number - recent P4s may have a different count). Is it any mystery, then, why the G4 uses so little power in comparison?

      I'm not discounting your ideas totally here - I'm just saying there is more to saving energy than throttling the CPU.

      In response to your last line - "most of today's solutions (power saving) are just a cure for the symptoms (bad battery time), not for the cause (bad battery technology)" - I have to say that although batteries are a hindrance, they are not much of one at the moment. Portables currently dissipate quite a bit of heat. If you increase the power they use (and increase the power given to them) you increase heat output, which is bad. Current laptops are about like holding a lightbulb against your lap. Are you sure you want that to be increased?

      The real limits with laptops these days have more to do with dissipating the heat they already produce than powering that mess. Upgrading batteries is not a solution to this, while more efficient processors are.

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  2. Re:Asynchronuous logic? by e8johan · · Score: 5, Insightful

    Another advantage of the ARM is the Thumb instructions that reduces the traffic over the memory bus. We must remember that driving memory bus is an expensive operation (power wise) compared to finding data in the cache. Smaller code means more code in the cache. One problem is that multimedia applications (such as movies, music, etc) fails to utilize the cache well (since the data isn't re-accessed). This is a problem area that needs more research.