A Question about Virtual Memory.

[dxp969]

Doesn't Virtual Memory allow the system to consume as much memory as the Virtual Address Space allows?


I think I'm to understand that the purpose of Virtual Memory is to free up the system from memory constraints and allow it to use it's full power, rather than give it some kind of obscene access to unlimited resources.

I'm at a lost though in understanding how much resources the next-gen systems will be able to consume and still remain in real time.

Say you had plenty of room in the Virtual Address Space, like 10 Gigs or so. Would any of the Next-gen Systems be capable of handling 300 megs of texture per frame(Toy Story 1 level I believe) and still run in real time?

 

[Guden Oden]

Depends on what you mean by "realtime" of course, because all that virtual memory data still has to be stored somewhere, and that somewhere has traditionally been harddrives. And harddrives are terribly slow.

Main memory access time - which is very slow by CPU standards, several hundred clocks of latency from the CPU's point of view - have an access time of some tens up to one or two hundred nanoseconds or so.

A typical harddrive has an access time between ten and fifteen milliseconds. This is hundreds, if not thousands of times slower... So if you think a next-gen console could page hundreds of megabytes of data in and out of main memory on a per frame basis... Think again buddy!