Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!sgi!tarolli@westcoast.esd.sgi.com
From: tarolli@westcoast.esd.sgi.com (Gary Tarolli)
Newsgroups: comp.graphics
Subject: Re: Distributed GL graphics via high speed networks...
Summary: dgld workings
Message-ID: <104738@sgi.sgi.com>
Date: 17 May 91 15:02:09 GMT
References: <1991May13.191050.21842@eagle.lerc.nasa.gov> <3869@borg.cs.unc.edu>
Sender: guest@sgi.sgi.com
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 35

In article <3869@borg.cs.unc.edu>, banks@homer.cs.unc.edu (David Banks) writes:
> How does the distributed graphics demon work? Are there 
> multiple servers for a single database that send their
> transformed polygons to a single display? How much faster
> is it on the machines you are using?

The dgld daemon works as follows:
	*) there is one daemon per dglopen connection, this usually means
		1 per GL pgm since most GL pgms don't open multiple
		connections.  Note that we are talking connections, not
		windows.  A GL pgm can open up to 256 windows per
		connection.

		A nice side effect of this implementation is that, unlike
		the X server model, one hung or busy server does not hang
		all the windows on the screen.  And the DGL server does not
		have to do a "select" call after each GL primitive.  The X
		server does, in order to offer fair time-sharing, and this
		is why most X servers cannot process more than a few
		thousand protocol request per second.

	*) Each server acts mostly as a "wire".  For each GL command it
		recieves, it simply calls the GL. If there is any data to
		be sent back to the client, the server collects this data
		and then sends it back.

So, as an example, if  you are running 2 GL pgms remotely, there will be
2 dgld daemons running - one for each GL pgm.  How much time each server
is allotted, and when, is up to the OS.

As for how much faster it is , I cannot answer cause I do not know what
you wish to compare it to...

--------------------
	Gary Tarolli