[Radiance-general] compiling Radiance 64-bit?

[Ian Tester]

On Wed, 03 May 2006 09:20:53 -0600
Rob Guglielmetti <rpg at rumblestrip.org> wrote:

> Hello Radiance Users, Abusers and Confusers,
> 
> Please excuse my ignorance, but assuming one has a computer with a 
> 64-bit operating system (SuSe Linux) installed, can Radiance be compiled 
> as a 64-bit application?  And if so, has anyone done it?  What's the 
> makefile look like?  The reason I ask is that I'm looking at possibly 
> building up a quad system (two dual-core cpus) and with the potential 
> for four jobs running at once I think I need more addressable memory.  
> As I understand it, with a 32-bit application you're limited to 4GB 
> total, whereas with everything 64-bit, the system can address 8GB of 
> RAM.  Since I rarely see jobs needing more than 2GB of RAM, I figure 
> having 8GB available for a maximum of four jobs means no job would 
> likely ever run out of RAM and start paging.  Maybe my first question 
> should really be: am I thinking about this correctly?  =8-) 
> 
> Any input appreciated.  (I think I need coffee.)
> 
> - Rob

I got it compiled without any troubles on my family's Sempron 64 (MythTV
box). It's running the unofficial AMD64 port of Debian, which is a full
64-bit port i.e not simply running 32-bit userland programs on a 64-bit
kernel. Everything is compiled to use the extra registers and SSE2, etc.

I simply changed the OPT line in the rmake file:
OPT=-O4 -march=athlon64 -msse2 -mfpmath=sse -ftree-vectorize
-falign-functions=8 -ffast-math

That's for GCC 4.0 and is hopefully making some use of SSE2 to speed
things up. In simple tests, the little 1800MHz Sempron 64 with 128KB of
cache is about 10% faster than my 1900MHz Athlon XP with 512KB of cache.

As for memory, it depends on what you're doing. Are you dealing with
complex geometry or large textures?

Hope that helps,
bye