[Radiance-general] starting rpict -S 1 -P pfile

[Lars O. Grobe]

Hi Greg!

> There's no sense in using the -P option if you're after parallel runs, 
> because -P insists on serial runs -- it's a mechanism to connect 
> sequential invocations to the same process.  It's exactly the opposite 
> of what you need.  Just use multiple rpicts if OpenMosix doesn't 
> support shared memory.  It will be the same as using -PP in that case, 
> since there's nothing about the -PP option that *requires* shared 
> memory.  It just ends up using it if it's available.

Well, the reason why I wanted to use -P is that I need some way to make 
the processes render just the missing frames. So they need to be 
synced. If I use just several rpict's without -PP, I will have to split 
my view files, and that means that I have to regroup the views in the 
view files each time that the cluster configuration changes.

The problem with using rpict with -PP is that rpict will share memory, 
and than openmosix will not allow the processes to migrata any more. So 
if the -PP option is the only way to make multiple rpict processes 
sync, I will have to go back and use a target for each view in my 
Makefile. Than I can use make -j # with # being the number of machines, 
the most generic way to distribute the processes. I am not too happy 
with that because I will have the problem with the viewfiles sooner or 
later when starting animations - I cannot have one target per frame, so 
I will have to find a way to render ONE viewfile's views in parallel 
without that "shared memory".

In fact I am seriously considering using ranimate for my stills now, as 
this allows me to distribute processes from ONE viewfile. I could 
simply add HOST-lines pointing to localhost, which is a bit silly, but 
should work fine.

Thank you for all the help, and have a nice week-end, we have a nice 
sunny autumn day here and it is a pity to stay in the lab ;-)

CU Lars.