Friday, 28 November 2008

Tracelight and Another 8800 GT

Last week I purchased another 8800 GT.  Although I would really like a 280 GT they are just too expensive and by buying another 8800 I can play with multiple GPU code. After some initial teething problems with video drivers and my machine going blue screen all the time I have the 2 cards working happily.  Unfortunately my machine dropped from x16 pcie to x8 to each card. This is not too serious for me as I don't move too much data over the bus between cycles (apart from the rendered image).

Using two cards gives a lot of flexibility as you can essentially run two kernels at once (Same or different ones). Currently I'm playing with each card rendering half the screen and then stitching them back together on the primary card.

The api I am developing for molecular visualization will now get support for multiple gpus thus fitting in rather nicely to the launch of the Tesla personal supercomputers. Somehow I got invited to the launch of these beasts next week. I'll be sure to post about that.

As mentioned in the title "Tracelight" will be the new name for "cudart" due largely to the fact that cudart.dll is a cuda dll and a lot of confusion has resulted. When I originally thought of the name I didn't realize the naming conflict. As a result there are a large amount of search hits on this site for cudart help referring to problems with the dll installation rather than ray tracing related searches.

Expect some more demos of tracelight soon from both the molecular api branch and the triangle mesh branch. It has its own domain ( but for now just links back to


Although I don't usually post personal stuff on my site or anywhere on the internet for that matter I think this is worth making an exception for (and kinda explains the lack of updates in the last few weeks). An added benefit is that it becomes searchable and I cannot forget the date...

On the 18th October I got engaged :)   Yes I did the one-knee thing and everything and she said "yes" :)  Quite brilliant.  We are getting married early next year and it has been quite a few mad weeks making arrangements. Its just incredible how far ahead venues and wedding related stuff gets booked up.

In unrelated news:  BT managed to cut off my entire street for 4 / 5 days. When reporting the fault they first said:  "there is nothing wrong with the line"   after me insisting there was a problem I got "well you better contact your ISP as it could be there problem".  This was rather amusing as they ARE my isp.... and not only was the internet dead the phone line was completely dead too.  Eventually I got hold of a technician who immediately told me (literally in the first sentence) that it was not his fault. Finally after many calls to them and lots of wasted time they admitted "a fault" and then took 4 days to fix it. Still no speed increase though. We live in the m4 corridor and still only get 768kps even though they sell the product as 8mb. No competition so what do they care.... /rant

Expect more rendering related posts shortly.