Actually, I think John Carmack may be refering to the "general" (or combined) memory challenges on PS3. I believe these include:
* 256K Local Store
* Partitioned memory requires carefully planned layout first (In some modes, I believe the SPU Local Stores must also be mapped to this global map, but my memory is vague now).
* Less available memory to work with due to OS reservation. So far, video memory seems ok (but the perception is still there). System memory seems to be the bottleneck for his work.
It is easier to summarize these challenges in one "memory limitation" statement rather than diving into the details (because they are somewhat related).
Some of these issues have a flip side (e.g., They are one of the reasons why SPU is blazingly fast, or the partitioned memory allows them to tap on secondary bandwidth should they run into the limitation elsewhere in the game).
I am just glad more engine is making use of Cell now. Sony, get the Epic one working quickly too.
* 256K Local Store
* Partitioned memory requires carefully planned layout first (In some modes, I believe the SPU Local Stores must also be mapped to this global map, but my memory is vague now).
* Less available memory to work with due to OS reservation. So far, video memory seems ok (but the perception is still there). System memory seems to be the bottleneck for his work.
It is easier to summarize these challenges in one "memory limitation" statement rather than diving into the details (because they are somewhat related).
Some of these issues have a flip side (e.g., They are one of the reasons why SPU is blazingly fast, or the partitioned memory allows them to tap on secondary bandwidth should they run into the limitation elsewhere in the game).
I am just glad more engine is making use of Cell now. Sony, get the Epic one working quickly too.