gauging interest in VAX 6000-530

From: Mike Cheponis <mac_at_Wireless.Com>
Date: Tue Oct 26 01:20:18 1999

The Great Initialed One (spc) states:

>Mike Cheponis sez:
>>
>>What I'm TRYING to do is to understand the performance of old machines
>>in terms of new machines; what I don't understand is why so many people
>>are uptight about this. Heck, we might all even learn something, eh?
>
> Why exactly?

Why? Exactly? Well, I want to know just how "powerful" these machines
really were. One way to do that is to actually work on them, and another
way is to compare them to machines that I understand.

For me, it helps put these machines in perspective.

You know, it's funny, I just made this (what seemed to me obvious) observation
about the Dhrystone 2.1 performance, figuring that other people would be
pleased to have some anchor on performance they (like I) could relate to.
But, instead, I've had to change my Asbestos Suit here several times! ;-)


>>it! That's a very very simple statement of fact, why is this -sooooooo-
>>difficult for so many on this list?
>
> I don't think it's difficult. Yes, a Pentium is X times faster than a VAX
>in integer math. But what I'm curious is to why is that important?

Because I develop software. I Edit (Integer), Compile (and an optimizing
compiler really grinds away in core, err, memory), and Run (usually integer).

Since that's what I do, that's what I want a system to do -well-.

>Yes
>siree, many's the time I wanted my computer to nothing but adding huge lists
>of integers as fast as possible. The more the better. I don't actually
>care about anything else than adding lists of integers.

Do I sense a wee bit of sarcasm here? ;-/


>>Peter, you'll note that I said that there are some cases where "channel-to-
>>channel" I/O occurs, but I call that "Simulfax Shuffle Time" (after
>>Firesign Theatre) - that is, in general, except for the special case of
>>file copy for backup, moving data around without processing it is a logical
>>and architecture error (or at least, inefficiency).
>
> Please define what you mean by ``processing''. I can have the Amiga load
>data off the floppy into memory, then have it output that data to the sound
>chips, all without the data going through the CPU. I can have the Amiga
>load data off the floppy into memory and have it displayed and moved about
>with having it go through the CPU.

I can BLT bits around, too. But it doesn't help me compile data, or
to compute Viterbi syndromes of data, or perform some signal processing
on some data, etc...

"Processing" means it goes through the central "Processing" unit, or indeed,
through some "channel processor" that modifies data in some way, or at
least uses data to compute some other quantity. Some processor has to
comb over the memory.

> In fact, some high end [Internet] core routers don't even ``process'' the
>packets that they route. Or rather, the CPU in such routers rarely, if
>ever, ``process'' such packets. Data comes in one side, goes out the other
>in a more or less ``channel to channel I/O'' process.

The important point is "more or less" AND the whole -point- of routers is
that they are, to the extent possible, simulfax shuffle devices. But if
they were -pure- simulfax shufflers, then they'd be replaced with a piece of
wire.

Those routers are re-wrapping the IP when they send it out another port,
decrementing the TTL field, re-computing the IP checksum, and the low-level
(link layer) wrapper. Sure, much of this is h/w assisted.

(And, as I've said, s/w is just h/w that hasn't settled down yet...)


But if you're going to play semantic games with me, for example, saying that
the channel processors are NOT processors, then, fine. But they are,
indeed, processors. So saying that channel processors are just
simulfax shufflers is cheating (since they are processors).

But it's just a definition. Some say simulfax shuffling is processing;
OK, that's fine, as long as we define terms.


(You conveniently clipped my proof why one bus is often better than two,
 but what the heck - you must have agreed with me on that! 8-) )


> Like all analogies applied to computers, even this one is misleading.
>Yes, even though the single 2MB/sec gun can deliver the same amount of lead
>as two 1MB/sec guns, with two guns I can have better targeting, or have more
>of a spread.

I don't see the relevance here with your distinction; can you please
elaborate?


> -spc (Sure, I can have the CPU read every byte off the harddrive (IDE)
> AND then process it, but I still get better through put by having
> the hardware read every byte off the harddrive (most SCSI cards)
> and then process it ... )

I like SCSI, too.

-mac
Received on Tue Oct 26 1999 - 01:20:18 BST