The ON_DEMAND_PAGING
feature enables on demand memory allocation and paging using the MEM_VIRTUAL
model. ON_DEMAND_PAGING
is only available when the VIRTUAL_ADDRESS_SPACE
feature is enabled.
Normally when a demand is made for memory, the same amount of physical and virtual memory is allocated by the operating system. When the ON_DEMAND_PAGING
feature is enabled, virtual memory allocation of the user address space does not necessary mean that physical memory will be allocated. Instead, the operating system may allocate the corresponding amount of memory on a large swap disk partition. When this occurs, physical memory will be used as a cache for the swap partition.