Re: Serialized DRAW processes on TKO

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Angus Dorbie (dorbie++at++multipass)
Mon, 9 Mar 1998 10:06:24 -0800

Are you forking your draw processes?

You need to.

Also you should make sure you genlock the pipes.

Cheers,Angus.

On Mar 5, 8:41pm, Dave Pape wrote:
> Subject: Serialized DRAW processes on TKO
> Hi-
>
> We've recently started running our Performer apps on a 4 pipe
> Onyx2/IR, and noticed a disturbing drop in framerate as more pipes
> were used. It appears that Performer is serializing the draw
> processes when the Onyx is in a TKO-style configuration (pipes
> are displays :0, :1, :2, and :3).
>
> To verify this, I added some code to get timestamps at the beginning and
> end of the channel draw callback (which selects the stereo buffer, calls
> pfClearChan() and pfDraw()) on certain frames, and printed them later.
> The timing information clearly showed that the pipes were being drawn in
> sequence, rather than in parallel.
>
> On a wild guess, I switched the system to single keyboard mode (:0.0,
> :0.1, :0.2, and :0.3). With just this change, the draw stages for the
> different pipes now all start at the same time, and the framerate is
> back to what we'd expect.
>
> These tests were run with Performer 2.2 n32 and o32, and Performer 2.1.3
> o32. All three versions had the same behavior. We're using Irix 6.4.
>
> So, what's the deal? Is there something I might be doing, or not doing,
> which would cause this? (all the channels are attached together, and share
> the scene, draw func, and swapbuffers) Is it a Performer bug, and is
> there a fix?
>
> -Dave
>
> ---------------------------------------------------------------------------
> Dave Pape Electronic Visualization Laboratory, UIC
> pape++at++evl.uic.edu http://www.evl.uic.edu/pape/
>
>
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>-- End of excerpt from Dave Pape

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