Re: Round trip query to the X server.

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Bernard Leclerc (bernard.leclerc++at++discreet.com)
Wed, 17 Nov 1999 11:59:22 -0500


Phil Keslin wrote:

> At present, Performer does not track the viewport state. This requires
> that the viewport be reset every frame (and hence the window geometry is
> retrieved every frame). We have looked at fixing this in the past, but
> haven't addressed it yet.

Phil, it's been a week since I posted my original message to
info-performer. Since then, a colleague suggested I look into promoting
the X server priority to the real-time band. It works well.

But I still think that GL and/or Performer should perform caching on the
viewport setting and avoid doing unnecessary round trip request to the X
server. Is there a plan to address this problem?

In the meantime, if anyone is interested, here are the steps required to
ensure pretty damn good response from your O2.

1- Boost the X server priority

        $ npri -s RR -r 120 -p XsgiPid

2- Also boost the window manager priority

        $ npri -s RR -r 20 -p 4DwmPid

3- In a normal shell, run "osview -i1" to observe the swapbuffer rate.

4- Try the simplest Performer program such as simple.C

        $ npri -s RR -r 10 simple x29.sv

Notice how stable the output is even under heavy system activity. For
instance, on my machine, a low priority background task uses all the CPU
spare time. So basically, my O2 has 0% spare CPU time. Even under this
heavy load, the above steps allow a simple Performer program to run
close to real-time. The example above runs at a steady 72 Hz on my O2.

That's all!

-- 
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t 514.954.7317                   10, rue duke
f 514.393.0110                   montréal (québec) canada
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