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From: tttron@escher.lerc.nasa.gov (William Krauss)
Newsgroups: comp.sys.sgi
Subject: Re: supercomputers, DGL, FDDI (longish)
Message-ID: <1991Mar21.185607.27254@eagle.lerc.nasa.gov>
Date: 21 Mar 91 18:56:07 GMT
References: <1991Mar20.163153@anusf.anu.edu.au> <1991Mar20.193615.2846@eagle.lerc.nasa.gov> <92563@sgi.sgi.com>
Sender: news@eagle.lerc.nasa.gov
Reply-To: tttron@escher.UUCP (William Krauss)
Organization: NASA/Lewis Research Center, Cleveland
Lines: 48

In article <92563@sgi.sgi.com> tarolli@westcoast.esd.sgi.com (Gary Tarolli) writes:
>I thought I would shed some light on some of the recent DGL discussions...
>
> ...tech stuff deleted...
>
>
>Second, starting the DGL daemon (called dgld) on the graphics server involves
>a one-time change to /usr/etc/inetd.conf.  The only installing on the
>CLIENT is to make sure the service called sgi-dgl is defined (in /etc/services
>unless you are running YP).
>> 

Yup, (it's what I do!!). I realize that there ARE a few things that can be 
omitted, I was NOT implying that I was a DGL guru or anything (I just thought 
I'd give a general description of what/how it works and my limited experience
with it.) We could get into a technical "joust" but I humbly concede.
Now, I have access to the EXPERTS (I know where you live!!).

>
>Ethernet performance for rotations etc. and real time motion can be quite good
>if one uses display lists.  To achieve 30 frames per second motion based on
>mouse input requires about 100 packets a second between the client-server.
>This is not impossible on Ethernet.  However, if you attempt to use immediate
>mode graphics and the DGL, then you will be limited by the bandwidth of
>the network.  The wiser option is to use display lists if possible, when
>using the DGL.  That way the network traffic to redisplay an image can
>be reduced by orders of magnitude.  We (SGI) made sure that display lists
>were fast and also supported all the new bgn/v/end commands, so that
>you could take full advantage of all of our new graphics (eg. VGX) and still
>use display lists.  I wrote up a very long and technical chapter regarding
>DGL performance and how to measure and tune it.  See the 4Sight Pgmers Guide,
>Version 3.0, Chapter 6 and Appendix B for more details.
>
>
>--------------------
>	Gary Tarolli

Thanks for the info! Now I'm an "armed and dangerous DGL warrior!!"i
(or should I say thanks for the "light!")

-William



--
>>>> William D. Krauss			NASA Lewis Research Center  <<<<
>>>> Graphics Visualization Lab		Cleveland, OH 44135    USA  <<<< 
>>>> tttron@escher.lerc.nasa.gov(128.156.1.94)      (216) 433-8720  <<<<