From: mark@taylor.uucp (Mark A. Davis) Subject: Re: X terminals: Suggestion for projects like SLS, MCC, etc. Date: Tue, 15 Jun 1993 02:27:18 GMT
hasty@netcom.com (Amancio Hasty Jr) writes:
>In article <1993Jun14.194758.18781@beaver.cs.washington.edu> pauld@cs.washington.edu (Paul Barton-Davis) writes:
>>In article <1993Jun14.145054.20767@wixer.bga.com> rhodesia@wixer.bga.com (Felix S. Gallo) writes:
>>On our instructional netwrok, we have (had) 2 hosts supporting 32 X
>>terminals along with another dozen or so ascii terminals. That makes
>>about 44 of the *most* demanding users: CS undergrads. Ever seen what
>>a decent session of nettrek does to your system ? Let alone our own
>>client/server multi-player dogfight, an application that makes large
>>database queries look like "grep" in comparison (network load wise,
>>anyway).
>I am curious as to the performance of such a network and the host
>computer?
He has already responded to this question in another posting, but this
brings up a point I had been trying to make earlier on. The server
(The X server running on the Xterminal) we retain it's specific X performance
regardless of how many terminals are installed, exactly like a workstation.
Only the overall performance will reduce as more terminals are added.
(greatly dependant on the host). Memory and disk are shared among all
processes (sharded libs) reducing the demands considerably on the host.
Typically, though, control is an issue when using such terminals. For
example, on our system no non-work related programs are available to run
on the xterminals such as games, maze, demos, etc... which would seriously
degrade overall performance and network bandwidth. It isn't terribly hard
to keep overall performance high, but one does need to look closely at
which programs are available. I found one program (forget what it is off
hand) that was creating a good amount of Ethernet traffic even though it
was doing nothing (drawing nothing, changing nothing) (although not high-tech,
I screen stuff by looking at a 10-t cluster unit's activity lights).
That program hit the trash can fast. Although it is rare, one needs to
watch out for things like that... even an xclock with a sweep hand isn't a
good idea. A minute hand is just fine, and reduces traffic for that
process by 98.3%.
One can allocate almost half the Xterminal's memory (with minimal config)
to act as a font cache too. For all the apps I run, it is rare it needs to
ever load fonts (further reducing traffic and load). I assume most brands
have this feature.
When one follows these types of guidelines, it is surprising how many
Xterminals could be supports (with typical loads, etc). But if you have
heavy, heavy, graphics users, high end workstations are probably better
unless you have some super-duper-radical-killer host ($$$$$$$$$).
I even know of several people who put a single X terminal on their single
user home unix systems to gain performance. Because the programs are run
on the box and the highly specialized graphics engine in the terminal ran
the X graphics, the performance was much higher than could ever be arranged on
just the box alone. (without the box costing 5x his arrangement) (I thought
the configuration was strange, but hey, whatever is needed!)
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