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Boosting Battery Life For RISC Processors
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.
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).
[BLOCKQUOTE]
According to the article:
Arm's Intelligent Energy Manager solution implements advanced algorithms to optimally balance processor workload and energy consumption, while maximizing system responsiveness to meet end-user performance expectations.
Transmeta's only claim to fame for their chips was using software to reduce power consumption, and it worked -- obviously, the Intelligent Energy Manager is just a ripoff of Transmeta's design. Linus should sue. [/BLOCKQUOTE]
Umm, no? These aren't CPUs used in computers and laptops.. these are used in handheld devices and embedded applications. I develop for ARM personally and the "algorithms" (note: they do not say software) is simply silicon embedded within the processor.. not software that runs on the processor itself.
As the poster mentioned, I doubt this will affect any laptops. I don't know of any that run off ARM cores.
http://www.arm.com/news/powerwise1111
They're basically targetting mobile phones and similar embedded systems like PDAs, because this is where ARM's main market share is at the moment. They say that they're looking at a more system-wide approach than is currently used, and they want to standardize the embedded software/hardware interface as part of this.
Also, note that "samples available Q2 2003" doesn't necessarily mean actual silicon. ARM doesn't make chips, they license their designs out to other companies which use them as a basis for an actual chip, so a "sample" quite likely means a software simulation. Actual devices which use this technology probably won't be around until 2004 at least.
That is one method of doing it (turning of clock trees to shut down a set of gates). One other way is to adjust the supply voltage and clock frequency to the CPU core. As ARM allready utilizes clock gating, the voltage/frequency technique is a very viable option for even more efficient CPUs. I'm usually not a big fan of Intel's, but look at their XScale and the measures they've taken to preserve energy. I have to say that I'm impressed!
It is a simple question of market laws. The x86 architecture is the ruling class, therefore it gets most of the research money, and as a results has the fastest running processors.
When the ARM came out, it blowed the 386s (The top x86) and 68020's out of the water. We were talking 3-4 times faster. And when the ARM3 came out with it's cache, it really kicked 386 ass.
And remember the Alpha? Another RISC design that was way ahead the rest. The only one left is the PowerPC family, still holding on to the x86 juggernaut.
And programming the ARM was a bliss. 13 general purpose registers, the barrel shifter. (Do a arthimetic and shift in the same instruction) Conditonal branching... It was a real joy. The x86 assembler is what programmers do in hell.
J.
That's a nice range there.
Me: Hey Jim, we're throwing a party at your house tonight.
Jim: Great! How many people are gonna come? I need to know how much beer and hoes to pick up.
Me: Oh, plan on somewhere between 25 and 400.
Yes, wouldn't it be wonderful? Instead of compiling down to LISTS of instructions, we compile every program down to a SINGLE instruction, designed in hardware to do whatever that program does. The speedup would be immense. Admittedly, there would be some pressure on hardware designers. Personally, I still think all hardware should be implemented in software...
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.
As an old Acorn user who switched to Mac back in 1998, I can safely point you to this fact without appearing anti or pro Apple/IBM/ARM.
"ARM Company Milestones: ARM History - 1985 - Acorn Computer Group develops the world's first commercial RISC processor"