Re: Short Vectors Versus Long Vectors

On Wed, 24 Apr 2024 02:00:10 +0000, mitchalsup@aol.com (MitchAlsup1)
wrote:

Everyone has to have hope on something.

But false hopes are a waste of time.

The reason for my interest in long vectors is primarily because I
imagine that, if the Cray I was an improvement on the IBM System/360
Model 195, then, apparently, today a chip  like the Cray I would be
the next logical step after the Pentium II (OoO plus cache, just like
a Model 195).

And that's a very naïve way of looking at the issue, so of course it
can be wrong.

I can, however, believe that latency, not bandwith as such, is the
killer. That's true for regular CPU compute, and so of course it would
be a limiting factor for vector machines.

What do vector machines do?

Well, apparently they do things like multiply 2048 by 2048 matrices.
Which is why they need stride. And since modern DRAMs like to give you
16 consecutive values at a time... oh, well, you can multiply 16 rows
of the matrix at once. Each matrix would take 32 megabytes of storage,
so that does fit in cache, at least.

But they've managed to get GPUs to multiply matrices - and they're
quite good at it, which is why we're having all this amazing progress
in AI recently. So it's quite possible that long vector machines have
too narrow a niche, between plain CPUs (more flexible) and GPUs (less
flexible).

John Savard