gauging interest in VAX 6000-530

From: Mike Cheponis <mac_at_Wireless.Com>
Date: Mon Oct 25 03:24:41 1999

> > That's fascinating. Take obsolete hardware and architecture (vax), and
> > keep them running! I guess I will never cease to be amazed at the weird
>
> Here's the clue to understanding it: software and business logic.

Sure, if the old stuff works, why change? (Even if it -is- obsolete!)
It does indeed make sense.

> I do believe at one point you stated that a dx2-66 could beat a
> VAX 8650 on any application (I don't think these are your exact
> words, something like crushing one). This is what people are
> reacting to, I don't think anyone is arguing about the difference
> in integer performance.

Thanks for helping me understand. I certainly believe the dx2/66 would
make the 8650 cringe on any app, but I'd want to collect all the data on
the 8650 (or 6500, for that matter) that would completely describe the I/O
busses, memory busses, etc before I'd say for -certain- that the dx2/66
would kick old vax butt.


> > >These are very different machine configurations, and even the latest
> > >PC would have no hope of keeping up to a decade old VAX running
> > >a large multiuser application.

I don't believe this.



> SGI is not selling any NT at this point, and its not clear that
> they ever sold very much. The NT experiment at SGI is over, and
> there are attempts to sell off what they can of it. SGI has
> gone back to building big servers, and Unix/Linux based ones.
> They realized that they weren't going to be able to scale
> an NT solution, and their strength was in scaling.

Yeah, this is an interesting gamble for sgi. Microsoft, of course,
heavily believes in Win2k, including its scalability. In fact, I think
W2K is going to do very well, as it is really pretty nice (I hate saying
that, but, again, I'm trying to call 'em like I see 'em...).


> > BUT, I would like the Vax Lover Crowd to acknowledge that they integer
> > performance of their machine is pathetic.
>
> No one in this group ever said it was good. As I said above
> the reaction was to your comment about PCs always being better
> than a VAX regardless of application.

I said a properly-configured PC would whip Vax butt in every case, yes.
But I -don't- believe that a single PC would be the correct -solution- to
deploy, as it is not scaleable or redundant. Clusters make more sense.


> > > Its not the speed
> > >of the individual bus, but its the number of busses.
> >
> > That's of course bull.....
>
> Then why does every large scale system maker build systems
> with multiple busses. Name one large scale system that
> has only one high speed bus. Surely they all aren't stupid,
> there must be some reason for doing this.

> > >The more busses, the more parallelism and the less waiting.
> >
> > -IF- the speed of the busses is high enough!


This is a really simple point here. If I have 10 busses and each one
runs at 1 megabit, is that any better than my one bus that runs at 100 Mb/s ?

That's the only little point I was trying to make. (Like the point that
you can bolt 16 VAX "CI" busses onto a modern PCI bus, and still have
leftover bus cycles.)


>>>One
>>>fast bus works well until you want to do multiple things, and
>>>then it quickly becomes a bottleneck.
>>
>>Excuse me? Could you please back up this assertion with data? After all,

> Which CPU? If I have a high end system I will be running multiple CPUs.

Yikes! Now we've jumped to Multiple CPUs! Yow!

That's a Whole Different Ballgame!

I've been reading Pfister's "In Search of Clusters" and I gotta say I'm
coming to the conclusion that uni-processors tied into loose clusters
gives the best bang for the buck (in all vectors: reliabilty, scaleability,
etc.).


> I agree about the problem of getting the data into the
> CPU, and as I pointed out this is the weak point of PC based
> systems. Everything goes into the CPU over a single bus, which
> has had problems keeping up with processor speed. Look at how
> many times Intel has changed the speed of the FSB over the past
> year or so.

Sure. And look how much bigger L1 cache is getting, and why more and more
L2 cache is onboad the PIII modules.


> > The thing that bothers me, tho, is that it's difficult to use such programs
> > unless the h/w is relatively similar.
>
> Our graphics benchmarks run on everything from low end PCs right
> up to high end workstations. We use lots of PCs, and we use
> lots of high end workstations, I need to know the cross over
> point in performance. If I can put an application on a PC I
> definitely will. I gain in price, upgradability and accessibility,
> but I can't do that with all applications (I wish I could, those
> large SGI machines are really expensive).

That sounds perfectly reasonable. Can you cluster some PCs to get a
pseudo-parallel machine?


> > That's the beauty (and downfall?) of benchmarks like Dhrystone 2.1 - it can
> > be run on most any piece of computer h/w every designed.
>
> Yes, and the results are typically meaningless.

Well.... I'm not quite so sure I'd go that far...


> Benchmarking
> is really hard, and typically the more general the benchmark
> the more useless it is. Here's a little example. Several
> years ago we went to two companies to evaluate their high
> end machines. According to the specs and benchmarks Machine A
> was the clear winner, at least 3x faster than Machine B. When
> we actually ran our programs we found that Machine B was
> consistently 2 or 3x faster than Machine A. This was a pretty
> wide range of applications. There are several reasons why
> this happened. One was that Machine B had much better compiler
> technology. The other was that the specs and benchmarks didn't
> tell the real story, how the machine really performed. Its
> easy to tune a machine to look good on standard benchmarks,
> but it may not run anything else at near that speed.


So this is a spread of maybe 6x or so between A and B? Just curious,
what were the Dhrystone 2.1 numbers for Machine A and Machine B? Could
you run identical OSs on them? Could you (if you wanted to) run identical
compilers on them?

Yes, I acknowledge the difficulty of making good benchmarks, but we should
start -somewhere- .


>> I know this. But, frankly, -every- bus is limited! Knowing how to "tune"
>> a system's architecture is partially what makes computers fascinating to me.
>>
>> It's also one of the main reasons I enjoy looking at and studying these
>> old behemoths, even vaxes? ;-)

> Well the IBM 390 architecture is still in use, which goes
> back to the 360 in the early 1960s. Thats a pretty long
> lived architecture.

That is long-lived. The 360 was the quintessential upward-compatible
architecture, right? "The "360 degrees" (full circle) of applications".

And s/w compatibilty was paramount.

My bet is we'll see the PC live for much much longer than the 360. It's
just evolution, eh?

-mac


> --
> Dr. Mark Green mark_at_cs.ualberta.ca
Received on Mon Oct 25 1999 - 03:24:41 BST