[/quote]I think that would break the (silicon) regularity of the Epiphany, impeding scalability, heat distribution and such. So I think it's unlikely.[/quote]
What I had in mind would still be regular - its just in each tile you'd have a core, and a cache (and maybe still a scratchpad.. mix and match. I remember platforms that had both). Just unusual. perhaps it would demand some memory protection scheme at least, a chip-wide 'cache-able region' register? no writes allowed.
Most data in a game engine is read only, and a lot of people are looking into double buffering for parallelism (john carmack has talked about this sort of thing, running the entire game update as pure functional, reading the previous state to produce the next, then swap & advance when its' all ready.).
I know from experience manually flagging specific data to be cached/uncached (e.g. original xbox) is a LOT easier than the full pain of DMA based programming everywhere (as we had on the CELL). With unified memory on the original xbox we had the hazard of the GPU not being coherent with the CPU cache, so graphics resources had to be assembled in regions allocated with CPU caching disabled (and CPU performance nosedived if you tried to read them).