gauging interest in VAX 6000-530

From: Mike Cheponis <mac_at_Wireless.Com>
Date: Sun Oct 24 16:24:54 1999

Mark Green wrote:

> Mike Cheponis wrote:
>> Looks like the 6500 was about 13 VAX-11/780 MIPS. That would make it about
>> 2x to 3x slower than a 486DX2/66.

> Integer performance is a very misleading
> measure of performance when you are talking about system performance.

My main belief is that nobody is going to keep a VAX anything running with
dozens of simultaneous users. So, if a VAX is to be something close
to "useful" today, it'll be in single-user mode. In that case, Integer
performance is very important.

Now, perhaps if we were to port Apache to the VAX, and used that I/O bandwidth
on multiple DS3s, well, that's great.


> for example, all except
> the most recent PCs, there is only a single bus. This bus
> must be used for all memory transfers, graphics, I/O, etc.
> On a single user system, this is sometimes okay, but for
> multiple users forget it.

Hey, I'm not saying the original IBM PC was going to outperform the VAX 6500;
but a modern PC will crush any VAX in any application, IMHO, with equivalent
h/w attached.


> Most of the VAXes had multiple
> busses, and each was dedicated to a particular function.

What are:

1) The names of these busses?
2) Their uses?
3) Their peak and average throughputs?

I certainly know for a fact that UNIBUS performed very poorly. I don't have
data at my fingertips, but it seems to me it was around 10 Mb/s (that
megabits/sec) peak throughput. [I prefer measuring throughputs in bits/sec
since that normalizes across different bus widths.]


> This meant that the combined throughput was considerably more
> than any existing PC bus.

I'm trying to get away from fuzzy terms like "considerably more" and get to
hard, cold numbers. Just -exactly- how fast were these things?

And, if you don't like Dhyrstone 2.1, then what benchmarks -can- we use?


>One of the main problems with
>all of the PC chips is the limited speed of the FSB. Its
>no good having high integer performance if you can't get
>the data in or out of the CPU.

Fast dual-port SRAM solves the problem, but commodity PCs aren't designed
that way. Also, the AGP bus uses mega-RAM to speed up PC graphics, for example.


> I do a lot of high end graphics, both on PCs and SGIs.

> of the SGI is at least 5x better than the best PC
> configuration, and it can bury the PC on any app that moves a lot of data.

I appreciate the SGI vs PC datapoint, but what's the PC vs VAX datapoint?


>Large systems were designed and built for throughput, so its quite possible
>that one of these old systems could outrun a modern PC in high throughput
>applications.

OK, then what's the performance of a VAX running Apache vs a K7 running Apache?

-Mike Cheponis
Received on Sun Oct 24 1999 - 16:24:54 BST