Paging dæmon

We have talked til now as if the kernel discards some pages when it requires frames. In actual fact, this may not be exactly the case. For example, in Linux, there is a process called the 'kernel swap dæmon', whose job it is to maintain a pool of free frames. It wakes up periodically and if the pool of free frames is low, the dæmon swaps some pages out to disk. When the kernel needs a frame, for a page to be brought into memory, it can instantly grab a frame from the pool instead of spending time, swapping a page out.

The paging dæmon keeps the memory system running efficiently.

last updated 18 March 1998