Re: Antialiasing and other RE stuff

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Jim Helman (jimh++at++surreal)
Mon, 28 Nov 94 13:03:32 -0800

   
> > Second, when running a 4.0.5 binary under 5.X, the multiple processes
> > are restricted to a single CPU by IRIX, so you won't get any
> > multiprocessing benefit.
   
> This I do not believe. I set the multiprocessing mode explicitly to
> APP_CULL_DRAW and it works fine (creating all the separate processes).
> So, unless the OS is nailing the other 3 CPUs somehow, it seems to run on
> more than one processor because I see all 4 being used. I do not know how
> to determine which processors are being used by my program, however. Is
> there a sysmp() call which would show this accurately? I'll have to check,
> I find this quite interesting. However, if you are right (which you
> undoubtedly are :) I guess I will just have to forego the IRIX 4 OS
> and recompile.

I should have said running a 4.0.5 binary under 5.X on an Onyx.
Power Series is OK.

On an Onyx, you will get multiple processes, and they might move
across CPUs, but IRIX will only let one Performer process run at a
time, effectively reducing you to a single CPU. Also, if you're
running with MP_DEFAULT, IRIX will only indicate that a single CPU is
available and Performer will run APPCULLDRAW.

The reason is that 4.0.5 Performer binaries statically link in
/usr/lib/libmpc.a which does not contain the MP semaphore and lock
code for Onyx. The IRIX compatibility solution was to only let one
process run at a time. I've also seen this cause deadlocks, yet
another reason to avoid 4.0.5 binaries on an Onyx.

rgds,

-jim helman

jimh++at++surreal.asd.sgi.com
415/390-1151

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