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.