multi-channel synchronizing

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Ran Yakir (rany++at++bvr.co.il)
Tue, 21 Jun 1994 20:23:37 +0000


Hi

I'm trying to run a dual piped system, which, upon arrival of hardware, should
become triple piped. Right now I have only 4 CPUs on my ONYX, su I use
PFMP_APP_CULLDRAW. The weird thing is that the left and right channels don't
seem to synchronize. Although their cull-draws run on different processors,
they tend not to run concurrently. Moreover, they skip frames in a manner that
channel 0 does frame # N, channel 1 does (N+1), channel 0 does (N+2), channel 1
does (N+3), and so on ... . Sometimes they suddenly sync, and run concurrently,
but not for long.
Just to be sure its not an overload, I asked pfFrameRate to be 10Hz (100 msec),
while the whole draw/cull thing takes less then 20 msec. I do plush the pipe at
the end of each frame to get accurate timing results.
In addition, I used the cpu locking utils from libpfutil, and runed as root, so
that they don't switch processors on me. And ofcourse I run with PFPHASE_LOCK.

Can anyone understand what that is ?

Ran

-- 
 __                                  | Ran Yakir
 /_)  _  __   \  / _   / o __        | Graphics App. Chief Engineer
/ )_ (_(_) )   \/ (_(_/<_(_)(        | BVR Technologies Ltd.
              _/                     |   
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Phone :                              | E-mail : rany++at++bvr.co.il
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