Re: MCO Performace

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Bernard Leclerc (bleclerc++at++cae.ca)
Mon, 7 Oct 1996 16:30:04 -0400


Eric Heft wrote:

> Hi,
>
> Anyone have an tips on how to optimize multipipe.c for use
> with a 3 monitor , 1 hw graphics pipe, split using a MCO?
> My sim can do 60hz when its just opening one pipe/monitor.
> When I go to 2 pipes , performance drops to 20-30hz. Even
> when I drop the number of object from 400 to 1!
>
> The hardware: Onyx
> 2 100 mhz R4400's
> 64 Meg main memory.
> 1 RE^2 Graphics board
> 1 MCO

Stop here... right now.

How many pipes do you have on your Onyx? Just one?

I strongly suggest to look at multichan.c instead of multipipe.c

>From the code you supply, I assume you want the MCO mode 3++at++960x680_60

Then, you should create only one pfPipe, one pfPipeWindow and 3
pfChannels.

        pfPipe* p = pfGetPipe(0);
        pfPipeWindow pw = new pfPipeWindow(p);
        pfChannel* left = new pfChannel(p);
        pfChannel* center = new pfChannel(p);
        pfChannel* right = new pfChannel(p);

I also suggest to share everything between channels except the view
offsets and the viewport.

        center->attach(left);
        center->attach(right);

        left->setViewport (0, 1, 0/3, 1/3);
        center->setViewport(0, 1, 1/3, 2/3);
        right->setViewport (0, 1, 2/3, 3/3);

        left->setViewOffsets( ... -FOV ... );
        center->setFOV(... FOV ...);
        right->setViewOffsets( ... +FOV ... );

Then in your simulation loop, you'll drive only the center channel
viewpoint position:

        while(1) {
                ...
                center->setView( ... );
                pfFrame();
                ...
        }

This setup will give you the optimal performance on a single pipe
Onyx/RE2.

To terminate, since you have 2 CPUs, you could pfMultiprocess your
application to ensure maximum throughput.

--
Bernard Leclerc			CAE Electronics Ltd., 8585 Cote De Liesse
Technical Leader		Saint-Laurent, Quebec, Canada, H4L-4X4
3-D Graphics Applications	tel: +1 514 341 2000 extension 2275
bleclerc++at++cae.ca			fax: +1 514 340 5496
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