Multiprocessing and more Optimizations

Tonight was the night for some more crazy optimizations for my Raytracer. I am almost done all the objectives for the Raytracer now which is sweet. Tonight I did Multiprocessing, so I am calling fork(), a system call which creates multiple processes. This has a slightly slower effect on my own Laptop because I have a Centrino processor, so it is not a Dual-Core and it is not Hyperthreaded either. So this does not have a specifically great effect. But, when running on the Hyperthreaded machines at school, it has a decent speedup, depending on the complexity of the scene. Essentially the purpose of this is to get the multiproc (or hyperthreaded) machine to act like to 2 machines working on one half of the image at a time. I join the processes at the end and combine the image together and delete the two image halves so that I don't have to do this manually in Photoshop.

So I don't have too many interesting images tonight, just lots of render statistics. But this is totally sweet cause it looks like it made a big difference.

The really cool thing though is tonight I tried running a compiler optimization flag, changing from a debug build to an optimized build. Well folks, the Venus De Milo model that was rendering in 46 minutes on my Laptop at home is now rendering in... 10 seconds!!! This is a 276 TIMES speedup... probably my most awesome speedup of all the Raytracing tests I have been doing. Sweet.


Venus De Milo runtime with 1 Process (94 seconds)


Venus De Milo runtime with 2 Processes (optimal - 77 seconds)


Venus De Milo runtime with 4 Processes (note this is slower than just 1 Process - 145 seconds)


Two processes from above (77 seconds), now runs in 22 seconds with an Optimized build


Venus De Milo on my Laptop with an Optimized build, was 46 minutes at start, now 10 seconds!


Table image rendered with 2 processes and optimized build


2 procs without optimization (~17.5 minutes)


2 procs with optimized build (~4 minutes)