Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!mordor!sri-spam!ames!amelia!msf
From: msf@amelia.nas.nasa.gov (Michael S. Fischbein)
Newsgroups: comp.arch
Subject: Re: Cray 2 has 2GW address
Message-ID: <305@amelia.nas.nasa.gov>
Date: 29 Feb 88 13:01:58 GMT
References: <416@micropen> <3534@killer.UUCP>
Reply-To: msf@amelia.nas.nasa.gov (Michael S. Fischbein)
Organization: NASA Langley Research Center, Hampton, VA
Lines: 33

In article <3534@killer.UUCP> elg@killer.UUCP (Eric Green) writes:
>in article <416@micropen>, dave@micropen (David F. Carlson) says:
>[NASA dude discusses running GNU Emacs on his Cray:]
>
>> I know most of these CRAYs are used in DoD research on important things like
>> bombs and SDI, but my running an EDITOR (ie. slow interactive process)
>> on a CRAY--presumably payed for with my tax dollars.  Ouch!  Can't you
>> find any good emacs for a VT100 on a VAX11/780 to run twenty editor jobs?
>
>the "Ouch" that you're talking about is the character-at-a-time task switch

One problem here that no one's brought up (so I will :-)).  The character
at a time problem isn't the Cray-2 context switch, (though it isn't a
context switching speed demon, it does do much better than a 780), but the
communications channel.  You don't hook a terminal to a Cray-2; you don't
even hook a CSMA/CD LAN to it.  You hook a fast token net (such as hyperchannel)
up so those big files (400MB and up) can be transferred in a reasonable
amount of time.  Of course, this leaves you scrambling for those one
character interactive packets.

If I remember correctly (I've got the reference here somewhere, but I'm
sure I'll get flamed if I'm far off -- or even just a little off), tests
on the first Ames Cray-2 showed twenty SIMULATED hot-and-heavy interactive
edits used about 8% of one cpu.  These were all running as canned scripts.
Unfortunately, they also simulated using more than half of the available
"outside world" i/o bandwidth.

		mike

-- 
Michael Fischbein                 msf@ames-nas.arpa
                                  ...!seismo!decuac!csmunix!icase!msf
These are my opinions and not necessarily official views of any
organization.