Re: Scheduling Performer procs under REACT

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Bruce Johnson (brucej++at++bruiser)
Tue, 16 Dec 1997 07:01:31 -0800

[Apurv Mathur hath proclaimed, on Dec 15, 13:27, in "Scheduling Performer
..."]
> Greetings!
>
> We are building a simulator application here to which I am
> adding real-time features provided by the REACT/Pro library. The
> visual process of the simulation is quite similar to 'perfly' and
> it is while scheduling this under REACT that I am facing problems.
> When I run a simple application without REACT in the FREE_RUN/LOCK
> and APPCULLDRAW mode, I get 72 Hz output. But when I try to schedule
> this application under REACT, the best I can get is only 24 Hz!
> I understand that Performer is trying to set its own frame rate which
> might not be in sync. with the frames I specify in my REACT code.

What timing source are you providing in your frs_create call?
To sync to the Vertical Retrace Interrupt (VSYNC) you should be
FRS_INTRSOURCE_VSYNC timing source which will give you minor
frame from which to schedule your processes.

>
> How can I make the frame rate of my visual process under REACT
> synchronize with the Performer frame rate ?

See above.

> Does it make sense to
> schedule the APP in real-time under REACT and let the DRAW/CULL
> and remaining processes be taken care by the Performer locking
> capability ?
>

Yes, Performer apps can and do run well synchronized with the REACT/Pro
frame scheduler in the following way (for example):

CPU 0 - IRIX scheduler; system CPU; background processes, etc.
CPU 1 - Performer; Cull/Draw
CPU 2 - Frame Scheduler w/ VSYNC; App

-- 
Bruce Johnson, brucej++at++sgi.com         "The future sure ain't 
Real-time Applications Engineering           what it used to be"
(650)933-3836                                   
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