Interesting. I had assumed that the threading overhead would be low enough that splitting the update integration and the collision systems to different cores would make sense. I'm still interested in learning about lock-free and data orientated approaches though (so that I know what to look for if/when I get an F1 car). Are there any open source projects that you know of demonstrating these ideas?
Atomicity, especially on multi-core depends on cache lines. The problem you should be worried about is false sharing. When two cores work on values sharing the same line, each write causes a cache sync, stalling both of them.
I see! That also may explain why my experiments haven't shown anything close to the performance increase I was hoping for (from profiling I know that the physics systems are the bottleneck). I only recently started reading about processor architectures and caching issues, so I'm still pretty new at this. I'll work what you've said into my current experiment and post some code later.
Thanks Evil Steve. I'd thought of that before, but my original approach still had a race condition (I was using one array of data and 2 arrays of pointers - one of active but read only data and the other write only but mutable). But I may be able to overcome it using tagged pointers. I'll try it out and post some code shortly.