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From: jsw@xhead.ESD.SGI.COM (Jeff Weinstein)
Newsgroups: comp.windows.x
Subject: Re: is the mit R4 server for PS2 slower than ibm's R3 version ?
Message-ID: <2643@odin.SGI.COM>
Date: 9 Jan 90 22:25:59 GMT
References: <9001090556.AA11528@expo.lcs.mit.edu>
Sender: news@odin.SGI.COM
Reply-To: jsw@xhead.ESD.SGI.COM (Jeff Weinstein)
Organization: Silicon Graphics Inc.
Lines: 34

In article <9001090556.AA11528@expo.lcs.mit.edu>, TRANLE@INTELLICORP.COM
(Minh Tran-Le) writes:
> why is the mit R4 server on a PS2 AIX 1.1 so much slower than the ibm's
> R3 server when you run the ico demo program:
>  ico -dbl -faces -colors red pink orange
>
> It is at least a factor x10 slower. Did I compile it wrong ?. It seems to
> behave like the ibm's R3 server when you don't have a 80387 floating point
> chip.

  What you are probably seeing is the effect of the R4 ico trying to
use the double buffering extension.  On the ibm product server ico
doesn't find the double buffer extension, so it does its fake
colormap double buffering.  On the R4 server ico finds the double 
buffer extension, and proceeds to use it.  The problem is that
the double buffering is done in software, and copies from memory
to the screen are pretty slow because of the architecture of the
displays on the ps/2.  So, if you want double buffered ico to go fast
you should disable the double buffer extension in the server.

  The ddx code on the R4 tape is pretty much exactly what we shipped
in the ibm product server.  It may have a few more bugs fixed, a few
bugs introduced by the R4 integration, and perhaps a few performance
enhancements.  You should see exactly the same or better performance
in the R4 server than the ibm product R3 server.

	--Jeff

Formerly IBM server hacker, now...

Jeff Weinstein
Silicon Graphics, Inc., Entry Systems Division, Window Systems
jsw@xhead.esd.sgi.com
Any opinions expressed above are mine, not sgi's.