From a implementation perspective, this is what I was trying to get at here. You
can, you've independent ad's going on, and they all happen in parallel So why,
why do we like multimedia extensions, or these vector instructions or short vector
instructions? And let's compare them to our big vector
machines. So, one of the major differences is that
you can't control the vector length. The vector length is the way the length
of the, the native data word or the length of the instruction set.
so, or the length, the length of the native data type for your instruction
set. And,
strided, scatter-gather, these other operations are hard to do,
because typically you just have a single load in store.
And you use the processor's load and storing instructions.
Because the processor doesn't care. It's just like the same way that unary
operations or logical operations don't need special instructions to do short
vector, or single instruction multiple data operations.
You don't need special instructions for SIM D data to be able to do loads and
stores. You just load the data.
And store the data. this is actually starting to change a
little bit. Some of the new versions of SSE actually
do have some, scatter-gather modifications.
It's a, it's a little bit harder if you think about it because you can't hold a
full address if you will, in a vector. So it's not like you can actually do sort
of index of addressing, index of addresses because you can't
necessarily hold the full address in there.
But, in essence, they've sort of come up with some way to do, scatter and gather
operations. Couple things about having the vector
register length being limited, is that you can't do as much work in one
operation. So, you can't necessarily do a 64
operations in one instruction, like we did with our vector length of 64.
So that's just, that just is a, is a problem.
And, and unfortunately, what happens here is you end up having to do more
operations and issue more instructions. And you're effectively increasing the
bandwidth out of your fetch, unit. So it's not, it's not, not as, not as
good. and finally, I just wanted to say we're,
that processors are starting to move, that these multimedia extensions are
starting to move a little bit towards vector processors. as they add more rich
instruction sets. So, as we get to SSC4 for instance, or
SSC4.2, there's more instructions in there and X 86 that can do fancier
things. And the vector length is even getting,
getting longer, up to 124 bits. Or excuse me 1024 bits.