[rescue] Re: [geeks] THIS. MAKES. ME. SICK.

[rescue at sunhelp.org]

mcguire at neurotica.com writes:

>On June 13, dave at cca.org wrote:
>> That wouldn't gain you anything. The performance difference between
>> a workstation and a super these days is almost entirely due to the
>> memory bandwidth & IO.

>  *bzzzzt*  Thank you for playing.

Ah, bullshit. :-)

>  You've forgotten about the performance of the processor, and the
>number of processors.  A Cray T932/32 can deliver a sustained 64GFLOPS
>of big-testicle 64-bit floating-point power.  You point me to a
>workstation that can do that, and I'll eat cat food in order to buy
>one.

They can't because they're crippled by the memory bandwidth. The 
latest RISC chips have peak theoretical FLOPS in the same ballpark
as Cray. They don't get *anywhere* *near* that performance,
because they're crippled by the rest of the machine, primarily the
memory bandwidth.

The number of processors has nothing to do with vector versus
plain-old-RISC. What I'm saying is that the outrageous performance
of the Cray vector machines, compared to todays high-end RISC
machines, is primarily, almost entirely, the rest of the box,
not the fact that it has vector instructions.

>> What surprises me is that we haven't seen a standard RISC chip thrown
>> in a box with a Cray-class memory system. (Well, I suppose that's what
>> the J90 is, actually...)

>  ...and, well, vector execution units.  And multiple processors.  And a
>crossbar switch for memory access.  And multiple I/O processors.  And
>the fact that the Cray PVP architecture isn't very RISC-like.

Woo - memory and IO. I said that, didn't I? Take a Cray, and replace the
CPUs with standard RISC chips. I don't think there would be much difference.

You might argue that it would be impossible to take advantage of that
much bandwidth without scatter/gather hardware. I'll give that one
point to the vector CPUs.

I consider Crays to be entirely RISC. RISC = Really Invented by Seymour
Cray, eh?

After all the hype and dust from the late 80s disappeared, what 
features defined "RISC"? Load/store and fixed-length instructions.
That's really all. Seymour invented that back in the mid 60s.

-- david fischer -- dave at cca.org -- www.cca.org -- Cthulhu told me to. --