Ken <tyl### [at] pacbellnet> wrote in message
news:37D181A1.FCA77AA4@pacbell.net...
>
>
> "John M. Dlugosz" wrote:
> >
> > Ken <tyl### [at] pacbellnet> wrote in message
> > news:37CF8EE8.892E1377@pacbell.net...
> > > Anyone else want to give it a try ?
> >
> > I use two CPUs and have some experience, so I'll give it a shot if
you're
> > interested.
> >
> > --John

On the use of POV-Ray for Win32 with multiple CPU's

The POV-Ray rendering engine is a single thread of execution, so when I run
it on my dual Pentium Pro (running NT4) the CPU indicator only goes up to
about 50%.  POV doesn't use more than half the available power on the
machine.

That's the basic issue, though to quibble a bit it's not exactly true:  the
rendering engine soaks up one whole CPU, but the editor runs on its own
thread, and operating system functions (writing to the file, updating the
display, network activity, system background tasks) run on different
threads.  This gives a little bit of a bonus, and the system uses as much as
54% of available MIPS when I watch it.  More importantly, the machine is
still highly responsive, and editing or other applications continue on
without being sluggish.

But for a long render, it's annoying to have one CPU be mostly idle.  What
can be done to cut rendering time in half (from 20 hours down to 10, for
example)?

The simplest thing is to run two copies of POV on the machine.  Have one
copy render the top half, and the other render the bottom half.  Then paste
the halves together in your picture editor.

One thing to watch out for:  don't just fire up two copies and point them at
the same INI file and image file.  They will overwrite each other's output
and make a big mess.  Instead, you must make sure each is writing to a
different file.

For moderate renders, I'll let one copy chug away on the long render, and
use a second copy interactivly to continue development in POV.

--John

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