On Mon, 18 Apr 2005, Sabuj Pattanayek wrote:

I don't know if this has been asked before (couldn't find anything on searches) but will there be a native amd64/emt64 (x86_64) build of chimera v1.2105?

You didn't say if you wanted a Linux or Windows64 version. The short answer is no. Partially because we don't have any of those systems in our lab, but also because we haven't yet encountered a scenario where it is useful. There two reasons for 64-bit executables: the ability to address more memory to handle larger problems, and to use new instructions that speed up floating point computations. The address space issue is lurking, but doesn't appear to be a problem today (please correct me if I'm wrong) because chimera really wants all of its data to fit in RAM and few systems have more than 4GB of memory in them. The floating point speed issue is more compelling, but chimera doesn't do much floating point except in a few cases (volume and surface calculations) and just switching to Pentium4 instructions instead of Pentium, might speed things up on more systems -- we're planning to do that experiment later this year as part of a larger optimization effort. So to summerize, when we get 64-bit Opteron/Xeon system, it will be possible to create 64-bit executables because we already have 64-bit executables for Alpha processors. But even on 64-bit architectures, it is often better to run a 32-bit executable because the same size problem uses less memory (32-bit pointers are half the size of 64-bit pointers), in fact that is exactly what we do for SGI IRIX systems. (There is one Linux 64-bit binary of an old version of chimera on our download web page that was made because older versions the 64-bit NVidia graphics driver didn't provide a 32-bit interface. My understanding is that has been fixed, so it is no longer necessary.) Hope this helps, Greg Couch UCSF Computer Graphics Lab gregc@cgl.ucsf.edu