A computing system includes a host and a storage device. The host includes a central processing unit (CPU) and a first volatile memory device. The storage device includes a second volatile memory device and a nonvolatile memory device. The CPU uses the first volatile memory device and the second volatile memory device as a main memory to store temporary data used for operation of the CPU. The CPU determines a swap-out page to be swapped-out of first pages stored in the first volatile memory device, determines a swap-in page to be swapped-in of second pages stored in the second volatile memory device, and exchanges the swapped-out page and the swapped-in page.