Question

I have been asked in an interview if virtual memory is infinite? I answered saying that it is not infinite. Then the interviewer asked the explanation and what I suggested was that in windows we do have a manual way to configure virtual memory to a certain limit.

I would like to know if Virtual memory is really Infinite?

Answer 1

First of all, forget the idea that virtual memory is limited by the size of pointers on your machine.

Virtual memory limits are not the same as addressing space. You can address more virtual memory than is available in your pointer-based address space using paging.

• Virtual memory upper limits are set by the
  OS: for example, on 32-bit Windows
  the limit is 16TB, and on 64-bit
  Windows the limit is 256TB.
• Virtual memory is also physically limited by the
  available disc space.

For an excellent overview, which addresses various misconceptions, see the following:

http://blogs.msdn.com/b/ericlippert/archive/2009/06/08/out-of-memory-does-not-refer-to-physical-memory.aspx