Path: utzoo!attcan!uunet!jarthur!usc!cs.utexas.edu!sun-barr!newstop!exodus!wind!naughton
From: naughton@wind.Eng.Sun.COM (Patrick Naughton)
Newsgroups: comp.windows.x
Subject: Re:  WANTED: Faster X server for Sun4 w/GX
Message-ID: <1990Sep27.205234@wind.Eng.Sun.COM>
Date: 28 Sep 90 03:52:34 GMT
References: <9009272115.AA09120@zia.aoc.nrao.edu>
Sender: news@exodus.Eng.Sun.COM
Reply-To: naughton@wind.Eng.Sun.COM (Patrick Naughton)
Organization: Sun Microsystems, Inc. - Mountain View, CA
Lines: 46

|> cflatter@ZIA.AOC.NRAO.EDU (Chris Flatters) writes:
|> I'm probably being a little loose in my use of the BITBLT designation.
|> What I really mean is XLoadImage (with and without various logical
|> operators set in the graphics context) since this is the bitwise display
|> operation I use the most.  At one time I was running with the GX board
|> unintentionally disabled due to an installation error so I managed to
|> get timings for image loads both with the GX board enabled and disabled
|> under OpenWindows 1.0.1 and found no measurable difference.  Of course,
|> now I mention it, I can't find my notes. 
|> 
|> 		Chris Flatters

--

XLoadImage performance has very little to do with which framebuffer you
are using...  Most of the time it takes to view an image using
xloadimage is spent reading the image from disk, converting it to the
XImage format from GIF/TIFF/et.al., and copying the data across the
network connection via XPutImage.  A more useful test of "BITBLT" would
be to time XCopyArea requests from offscreen Pixmaps to screen windows
and from screen-to-screen, (panning/scrolling).

Coincidentally, you can test this using xloadimage: resize the window
smaller than the image and when you see the little four-way-arrow
cursor, press the left button and drag the image around.  The
difference between a GX and a CG3 is quite noticable...

After re-reading your message I can imagine that you meant to say
XPutImage() the Xlib request, and not xloadimage the (very nice) image
viewing client by Jim Frost at Saber.  The above comments still apply,
with the clarification that XPutImage is a client side request which
requires the image data to be serialized and written to the network
connection and re-assembled in the server at the rate of the network
connection... No graphics accellerator in the world can speed up the
network.  The MIT-SHM extension can help reduce the overhead by using
shared memory and mmap() to speed up X{Get,Put}Image when the client
and server are on the same machine.

Hope this helps.

-Patrick

    ______________________________________________________________________
    Patrick J. Naughton				    ARPA: naughton@sun.com
    Window Systems Group			    UUCP: ...!sun!naughton
    Sun Microsystems, Inc.			    AT&T: (415) 336 - 1080