I am looking for documentation on the the Linux /proc file system, with regard to platform specifics for the Cell Linux platform. Of particular interest is how to identify if a given /proc/pid entry represents a process or thread on an SPU, versus on a PPE.
The system does provide some documentation in
man proc
This is the most detailed /proc guide I know of:
http://www.mjmwired.net/kernel/Documentation/filesystems/proc.txt
Anything more then that and I think you're probably going to have to look at the kernel source code. This annotated Python code for Cell might be a helpful starting point.
It looks at the moment like the /proc is pretty vanilla on Cell Linux. What is different is the presence of the SPU-FS in /spu, which exposes information about (and indeed, the contents of) processes executing on the SPU helper processors.
The source code for the spu-top and spu-ps tools (spu-utils) is useful for this.