Pretty much all resources relating to game programming, especially 3D open-world games, talk about how you have to constantly be unloading and reloading assets to and from disk, system memory, and video memory. I can understand this on consoles, as they have very simple memory management schemes that cannot deal with any potential overflow.

However, on the PC, the situation is very different. There is virtual memory provided by the OS for system memory and the graphics driver handles swapping back and forth from the CPU to the GPU. So why is it that it's not sufficient to load everything at once and only have to deal with prefetching and possibly making sure that there is no blocking while a required asset is being swapped?

This is not to say that everything is being allocated naively using something like malloc. Everything will be kept contiguous and cache-coherent. It's arguably easier to make your memory access efficient if you don't have to worry about paging in and out manually anyways...

Pretty much all resources relating to game programming, especially 3D open-world games, talk about how you have to constantly be unloading and reloading assets to and from disk, system memory, and video memory. I can understand this on consoles, as they have very simple memory management schemes that cannot deal with any potential overflow.

However, on the PC, the situation is very different. There is virtual memory provided by the OS for system memory and the graphics driver handles swapping back and forth from the CPU to the GPU. So why is it that it's not sufficient to load everything at once and only have to deal with prefetching and possibly making sure that there is no blocking while a required asset is being swapped?

This is not to say that everything is being allocated naively using something like malloc. Everything will be kept contiguous and cache-coherent. It's arguably easier to make your memory access efficient if you don't have to worry about paging in and out manually anyways...

UPDATE:

After reading a bit into asynchronous buffer transfers, I get the idea that the way the graphics driver can automatically page memory in and out is suboptimal. Does this also hold true for CPU resources; i.e., is it better to always manually manage when a given resource is to be loaded and unloaded even in the presence of virtual memory?

Pretty much all resources relating to game programming, especially 3D open-world games, talk about how you have to constantly be unloading and reloading assets to and from disk, system memory, and video memory. I can understand this on consoles, as they have very simple memory management schemes that cannot deal with any potential overflow.

However, on the PC, the situation is very different. There is virtual memory provided by the OS for system memory and the graphics driver handles swapping back and forth from the CPU to the GPU. So why is it that it's not sufficient to load everything at once and only have to deal with prefetching and possibly making sure that there is no blocking while a required asset is being swapped?

Pretty much all resources relating to game programming, especially 3D open-world games, talk about how you have to constantly be unloading and reloading assets to and from disk, system memory, and video memory. I can understand this on consoles, as they have very simple memory management schemes that cannot deal with any potential overflow.

However, on the PC, the situation is very different. There is virtual memory provided by the OS for system memory and the graphics driver handles swapping back and forth from the CPU to the GPU. So why is it that it's not sufficient to load everything at once and only have to deal with prefetching and possibly making sure that there is no blocking while a required asset is being swapped?

This is not to say that everything is being allocated naively using something like malloc. Everything will be kept contiguous and cache-coherent. It's arguably easier to make your memory access efficient if you don't have to worry about paging in and out manually anyways...