Fred Bosick (kcisobderf@yahoo.com) on 2/22/08 wrote:
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>
>You can have the fanciest algorithms around, but you still have to move bits, onto
>the monitor, on and off the disk, and, many times, to paper. What dismays me in
>commercial computing is how little "processing" actually takes place. Most of the
>data is just slightly gussied up alphanumeric strings, sometimes rearranged, sorted,
>and glommed together. Literally, just shuffled around! Maybe we need the mathematicians
>to invent even *more* sorting and pattern matching algorithms. I don't think that would interest them much.
>
More sorting and pattern matching algorithms isn't what I had in mind. The most difficult problem to solve is that the data (and/or instructions) you need are at the wrong place, and you can't get them to where they need to be in time. This fundamental difficulty has little to do with the switching speed of transistors in the CPU, and solving it through improving hardware latency is physically impossible.

It's not a new problem for computation, really, but we're at the point where you can have all the MIPS or flops you want for essentially the cost of electricity, but it doesn't help because the problem is, as you observe, not computation, but moving data.

>IMO, the fundamental measure of processing speed is how many transistors can be
>flipped in a given instant. Improving integer processing and branch traversal/prediction
>seems to be the best way to do this.

Branch prediction is only one of many kinds of prediction that need to be successful for modern processors to get anywhere near optimum performance. Branch prediction deals with what instructions should be fetched and executed. You still have the problem of getting the data you need, and that involves aggressive speculation and predication.

If there is fundamental work on what the theoretical limits of predictability are, I haven't seen it. The problem really isn't tied to hardware. It's the same if you're serving pages on the net or trying to get data into or out of cache. Tying the problem to hardware is inevitable if the problem is in the hands of computer scientists. Progress will come when that link is broken and the problem is addressed at a more abstract level.

Robert.