🚀 go-pugleaf

In article <706@brl-sem.ARPA> ron@brl-sem.ARPA (Ron Natalie <ron>) writes:

>>Ummm, I'm sure that Arete, Encore, Pyramid, and Sequent would be happy to tell
>>you about 12 MIPS superminicomputers with fast busses that sell for a lot less
>>than $400K for a fully configured system. Elxsi and Convex too, I think.
>
>Last time I checked (and I checked Pyramid recently) Arete, Pyramid, and
>Elxsi were not 12 MIPs.  

I don't know how Gould is measuring their MIPS.  If they're using Whetstone
MIPS (which is likely since the original posting mentioned that a
"math processor" was used to obtain the 12 MIPS), then a single ELXSI 
processor (model 6420) is about 12 MIPS.  The price for a single-CPU 
system is about the same as for the Gould.

>The bus on the new Gould is much faster than
>every CPU you listed.  

ELXSI's main bus is 320MB/sec, over twice as fast as the Gould's.

>There are two big advantages of the Gould.  One,
>it achieves it's speed using a small number of processors which makes
>it more attractive to some of the number crunchers than it would seem to
>someone who is just going to dump 100 users on the machine (which is where
>the ENCORE really excels).  

This comment also applies to the ELXSI.  It supports up to 12 64-bit
ECL gate array CPUs.  Works very nicely for number crunchers (applications
can even be parallelized to run on multiple CPUs simultaneously) and
for timesharing.  We have a customer who is supporting 1300 office
and "knowledge" workers on a medium-size ELXSI.  (Only 200-300 users are
ever doing anything at the same time, however.)  We also have people
using the ELXSI for number-crunching realtime activities like flight
simulation.

>The other big point is the ability for some
>really fast disk technology to be used.  Fast disks make UNIX sing.  For
>example, the C compiler on most machines is limited by the disk speed.
>Find the fastest disk you can, make it /tmp and watch the performance
>change.

You must be used to some very slow disks or very fast processors.  I have
never seen a disk bound C compiler on any machine that supports a reasonable
disk drive, unless you are talking about paging.  On the ELXSI, which has 
a very fast CPU and normally runs with the modest Fujitsu Eagles (1.8MB/sec 
transfer, ~25ms seek) the C compiler is almost completely CPU bound.  Speeding 
the disks up by a factor of 100 would have almost no effect on compile time.

Also, in those cases where disk performance is an issue during
compilation (normally heavily page faulting timeshare systems) it is
rarely a problem with transfer rate but much more likely a problem with
seek time.  Having a fast bus does not help in these circumstances,
except to the extent that it allows you to hook MANY disks up to
effectively overlap seeks.

There are certainly applications which require high disk transfer rates.
One of the reasons people buy ELXSI's is that they support direct mapping
of large files into user's address spaces yielding disk-to-user transfer
rates at nearly the hardware limit of the disk.  However these applications
are rare among our customers.  We have only one customer who is using
a higher disk transfer rate than the Eagles (2.4MB/sec).  
-- 
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Michael Sherman
...!{sun|styx}!elxsi!sherm