Ger wrote:
> When trying to run a render that uses over 3Gb memory I get this error
> 

...


> Keeping it below 3Gb (by reducing the number of lights) it works fine.
> 
> Just wondering if I should keep that 3Gb limit in mind or if there is
> something else going wrong.
> 
> Running:
> Athlon 64x2 3800+
> 4 Gb mem internal (6Gb swap) (so available mem should not be a problem)
> Suse 10 with Linux athlon64 2.6.13-15-bigsmp kernel
> Self compiled Povray 3.6.1

It looks like you know what you are doing, but here are some things I 
have run across regarding memory - based on 32 bit systems.

A single application (thread) is limited to using 2GB or 3GB depending 
on your OS and settings within the OS.  I have found that typically in 
Windows the limit is 2GB and Linux is 3GB (tho these can be affected by 
OS settings).  I have run into these ceilings myself running various 
applications.  I have found no way of allowing for more memory usage in 
a 32bit system.  I set up 16GB swap once only to have the application 
crash at 3GB.

Also, the OS might be capable of using much more than 2GB (or 3GB), but 
it must be in the form of separate applications (or threads).  It might 
be entirely possible to run (3) 2GB applications - tho I have not tried 
or tested this myself.  Others here with more knowledge can set me straight.

I remember that these is a configuration within Linux that allows it to 
use different memory mapping to allow for large memory usage.  If I 
remember correctly, it was a kernel option and required the kernel to be 
recompiled.

If your system is 64 bit, it could be that something is still limiting 
it to using 32 bit memory addressing.

Now, my experience is only with a 32 bit system.  I understand that 64 
bit systems have much different limitations, but I have no experience 
with them.  I hope that this sheds a bit of light for you.




LAter... Tom

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