Marc Schimmler <sch### [at] icauni-stuttgartde> writes:

> Juergen Schmidt wrote:
> > 
> > I want to do a demo for linux SMP-capabilities on a highend SMP-box with
> > povray.
> > 
> > Therefor I have a couple of questions:
> > 
> > - does povray support multithreading, or do I still have to split the
> > image into sepate processes.
> > 
> > - is there a decent frontend to split up the task for a SMP-box ?
> > 
> > - I read there is an unofficial port of 3.1a. Is it worth trying that
> > instead of the official version, i.E. do I get any benefit on a
> > SMP-machine? Does it compile/work with Linux 2.2?
[...]
> 
> 1. PVWPov (
> http://www.geocities.com/CapeCanaveral/Lab/6386/pvmpov/index.html )
> This work with the 3.0 version of povray.
[...]
> 
> If I'am right PVMPov has been used during the last WDR Computernacht on
> the Linux Cluster to show its efficiency 
> 
>  http://www.heise.de/ix/artikel/1999/01/010/default.shtml :-)
> 
> One of the participants has been Thomas Wilhalm of the Uni Konstanz who
> posts quite often in this groups!

I wasn't involved in setting up the version of POV-Ray that was used at
the WDR Computernacht -- I have just used the installed software. As
far as I know, they used a shell script to distribute the rendering. At
the cluster event, the rendered scenes were films. Each frame of a film
was considered as a separate job. The jobs were then distributed using
LIST-SCHEDULING: When a machine becomes idle, it gets the next job from
a given list.

PVMPov is more fine-grained. It is also useful to render a single image
on a multi-processor machine or several machines. The underlying software
is PVM. It provides a common interface to a "parallel virtual machine".
That means, that it is easily possible to use different types of computers
as one big computer.

PVMPov splits the image in several small pieces. A central server program
starts a client task on every virtual machine. The parts of the image are
then assigned to the client tasks.

Let me describe a concrete scenario: Let's assume you have a computer with
4 processors. If you start PVMPov with this information, then 4 tasks are
started where every task parses the scene and renders the parts of the
image as told by the server program. 

As far as I know, there is still a problem with halos. PVMPov doesn't
render them correctly. I haven't heard so far about a new version of PVMPov
that includes the changes of POV-Ray 3.1. 

POV-Ray 3.1 introduces a lot of helpful and nice features (mainly
file i/o, macros, and media replacing and extending halos). It does
however not help you with multi-processor machines.

I have no experience with PVMPov on Linux, but I have used PVM-Pov with
Sun Solaris. I have tried to compile PVM with Windows, but failed.
The current distribution of Linux by SuSE contains compiled binaries of
PVM-Pov and PVM.

Feel free to ask me here or per PM.

Thomas

-- 
http://www.fmi.uni-konstanz.de/~willhalm

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