Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cbmvax!grr
From: grr@cbmvax.commodore.com (George Robbins)
Newsgroups: comp.sys.dec
Subject: Re: Can a DECstation replace a 11/750 ?
Message-ID: <11319@cbmvax.commodore.com>
Date: 4 May 90 07:37:11 GMT
References: <36119@prls.UUCP> <5070@hub.ucsb.edu> <1990May4.025422.8656@spock.UUCP>
Reply-To: grr@cbmvax (George Robbins)
Distribution: usa
Organization: Commodore, West Chester, PA
Lines: 34

In article <1990May4.025422.8656@spock.UUCP> eric@spock.UUCP (Eric Volpe) writes:
> In article <5070@hub.ucsb.edu> aks@somewhere.ucsb.edu (Alan Stebbens) writes:
> >
> >Again.  It appears that you are overly concerned with size, and not
> >performance.  The DS3100 really runs at 15 MIPS, which is *fifteen*
> >times faster than a VAX/780.  If a VAX/780 could support 8 users, why
> >can't a machine which runs faster?  Again, size has absolutely nothing
> >to do with performance.
> 
> It is *not* *fifteen* times faster than a vax 780! the DS3100 is a RISC
> machine, meaning Reduced Instruction Set - Which means that each instruction
> on a RISC processor is very small and the equivalent of several instructions
> of a non-RISC processor. So, while it may be true that the DS3100 can
> execute fifteen times as many of its instructions in one second as a VAX780
> can of vax instructions, you're comparing apples and oranges.

Please, let's avoid the RWARS...

As soon as I got my 5810 up, I ran some dumb benchmarks, like some monster
diffs that were painfully slow on our 785.  I believe the performance ratio
was 9:1 and if you apply the standard 785:780 factor you get about 14 VAX
mips.  The 3100 is maybe two thirds of this, so you're in the 10 VAX mips
range.  Your milage varies depending on your driving habits.

Obviously this isn't 15 times 780 performance, on the other hand, a bunch
of RISC MIPS vs. VAX MIPS assertions don't exactly knock it back to 780
levels either.  I/O performance is obviously another issue, but for an
8-user system, you've probably got nothing to complain about, as long as
you invest in enough memory to avoid wasted cpu/disk resources for paging. 

-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)