Running X11 or NeWS on mainframes

[Bill Pieterouiski]

In article <6102 at drutx.ATT.COM> neal at druhi.ATT.COM (Neal D. McBurnett) writes:
 >Does anyone have any experience with running a lot of X or NeWS clients
 >on a Unix mainframe?  Given the way that per-character interrupts in
 >programs like vi or emacs tend to degrade performance, I wonder what
 >window systems are like.
 >
 >It would seem that NeWS would be better suited to migrating functionality
 >down to the server - have people done that with editors?
 >

Yup!  Here at Amdahl we're running X11 on our two main development domains.
(1 domain = 1/4 mainframe)   I'm not sure what you mean by 'lot of 
clients', though.  In our case, we have two domains with over 
300 simultaneous users, each!  Our user community consists of 46 
X-terminals (NCD 19 and NCD19c), lots of Sun workstations, and 
a few Solbourne workstations.  All using X11.  Plus a LOT of 
dumb terminals!
We've got 180 workstations and X-stations on the network, with
both domains on the same network.   The network also supports
a few Macintoshes.  All this on one wire!  Obviously, this
network configuration is far from optimum!

The results are very good.  The network is the weak link, of course.  The
mainframes can handle the load with ease, and do.  Response time is very
good, unless one of the domains dies and all 400 users migrate to the
remaining domain.  Then, the CPU gets bogged down.  But the same goes for
non-X users.  

We run Emacs and vi, no problem.  I/O is a mainframes strong point.  It's odd
to see the cursor pause, when the user load is very high, then a blast 
of output comes to the screen so fast if you blink you'll miss it.
The only significant performance hits are clients like 'ico' that
cause tons of network traffic.  The application works fairly well, but
other network users lose a little response.  Once again, the network is
critical.

We don't use NeWS, or the faster X11R4 yet.  Response time due to using
X hasn't been a problem.  Ask me again in a couple months.  We'll be adding
over 50 X-terminals to this same network!   

Any more questions?  Please ask!
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			Bill Pieterouiski
			UTS User Interface Development
			Amdahl Corp. o16, Santa Clara CA