Chipmakers Admit Your Power May Vary

Dylan Knight Rogers writes to mention a News.com story discussing the realities of chip power consumption. From the article: "Assessing only pure performance is passe. The debate these days is about performance-per-watt, which seems like it should be a simple miles-per-gallon type of calculation. However, miles are miles, and gallons are gallons. There's no one simple way to measure processor performance, and measuring the amount of power output by today's chips is proving just as difficult."

Comments

How is this news?

[AuMatar]

Performance being difficult to measure is well known- you can't go by clock speed, or even clock speed*instructions per clcok since these will differ based on instruction mix. For power, a simple inverter will use different amounts of power depending on if its on or off- exact power for a chip is impossible to guess. This is all old news.

Not indicative of real world performance

[0racle]

So it's exactly like the miles-per-gallon on new cars.

benchmarks

[Anonymous Coward]

This is what benchmarks are for. Compare the performance of two systems with other variables held as constant as possible. This has been going on for years, has it not? If I want a computer to play games, I see what different CPU configurations yield in, say, HL2 with the same ram and video card.

Is this perfectly scientific? No.
Is it practical? Hell yes!

Some miles are up hill and some are down hill...

[EmbeddedJanitor]

Especially with caching and pipelining, MIPS per W gets very difficult to measure. If you can live in the cache you don't need to go fetch from the outside world. If you stall the pipeline, you lose performance. Some operations (eg. DIV) clock a lot of transistors, some (NOP) don't. It was a lot easier to measure MIPS/W when devices were synchronous. Now they're a group of asynchonous entities (core CPU, cache,...).

BTW, EPA mpg are measured without using real mile on real roads.

It's not just the CPU

[Rosco P. Coltrane]

For most users (i.e. not power-users doing heavy calculations for some scientific purpose, or high-quality video editing, or raytracing), most processors provide way more power than needed, and have done so for years. Or at least, they *would* provide all that power if the software running on top of it wasn't bloated and unnecessarily complex, unoptimized and badly written. And no, I'm not just talking about Windows, I'm including Linux, MacOS and all the others in the bag.

The best proof that modern software makes modern hardware suck is that, back in the mid-eighties, I used an Atari ST to do desktop publishing, and it wasn't all that different from what I can do now with a simple PC that would look like a supercomputer back then.

Re:It's not just the CPU

[Burning1]

As a resource becomes more plentiful, uses for that resource also increase. A similar example from automotive engineering comes to mind:

Because of advances in engineering and design, engines are far more powerful and efficient now than they were in the early 90s. Cars have far better aerodynamics. However, gas mileage has not improved. In many cases it's gotten worse since the 80s. Likewise 0-60 times haven't improved much.

So what happened? Instead of improving the performance of your average family sedan, auto makers have added better armor, more air vents, more lights, DVD players, and more plush materials. Everything is safer and more comfortable now than it was in the 80s and 90s.

My 86 Camry will beat your 2007 Camry in a drag race and it will get better fuel mileage. But for a 500 mile trek across California or a bad accident? I know which one I'd prefer.

Likewise, my Pentium 4 has 16000 times more ram than my first computer (a C64,) and 256 times the ram of my first 486 (side note: how long before someone informs me of the amount of ram my 486 had?)

My 486 could write a document just as easily and with as much style as my P4. But it couldn't write a document while I was watching a subtitled MP4 movie in another window, listening to music, burning a DVD, and downloading hot lesbian pr0n from bit torrent. And it certainly couldn't do all that on dual 20 inch widescreen flat panel displays.

Sure, software is more bloated. But like the 2007 Camry (available wherever fine cars are sold,) after a long day your ass is going to be a lot more comfortable.

Re:Just as well...

[MyLongNickName]

May Heisenberg will protect us!

I have no idea what direction you are going with this. I have, however, determined exactly how fast you are going with this.

News?

[tomstdenis]

I'd think both AMD and Intel are well aware of the MIPS/Watt challenge. It's not new. Problem is CUSTOMERS still want a bazillion Ghz attached to the processor because they think it will make it faster or better or something.

I've got two x85 class Opterons sitting here at 1Ghz most of the time. That's ~35W vs. ~95W. AMD seems to care about power. Intel is no worse off with the Pentium M and "core" series (netburst was a mistake).

Tom