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From: jg@crl.dec.com (Jim Gettys)
Newsgroups: comp.sys.dec
Subject: Re: Switching from DECwindows to X11R4
Message-ID: <1990Dec10.160622.21740@crl.dec.com>
Date: 10 Dec 90 16:06:22 GMT
References: <MIKE.90Dec5105939@apex.yorku.ca> <70306@bu.edu.bu.edu> <27618197.29730@orion.oac.uci.edu> <370@srchtec.UUCP> <9606@pasteur.Berkeley.EDU>
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Reply-To: jg@crl.dec.com (Jim Gettys)
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In article <9606@pasteur.Berkeley.EDU>, mao@eden.Berkeley.EDU (Mike Olson) writes:
> straying just a little from the original subject of this thread:  we're
> running mit's R4 server on our decstation cluster at berkeley.  we have
> noticed the following curious fact:  identical X11 programs running under
> the identical X11R4 server binary do substantially faster screen drawing
> on our decstation 3100's than on our decstation 5000's.  we have none of
> the interesting graphics options on either our 3100's or our 5000's.
> worse performance on the newer hardware is counter-intuitive.  to be fair,
> this is the only instance of performance degradation we've seen.
> 
> can anyone offer a plausible explanation for this behavior?

I presume you are using DS5000/CX's...

The CX does not have a plane mask.  The DS3100/2100 does.  So for programs
which use plane masks .ne. all ones, it is possible a DS5000 could run
more slowly than a DS3100. (since the server has to do read/modify/writes rather
than just writes, for such operations).  The other graphics options on the
DS5000 do have plane mask hardware.  For most applications, the DS5000/CX is
substantially faster than the 3100.
				- Jim