Medium-term Scheduling 

Medium term scheduling is part of the swapping function. This relates to processes that are in a blocked or suspended state. They are swapped out of real-memory until they are ready to 

execute. The swapping-in decision is based on memory-management criteria: 

Determines when processes are to be suspended and resumed.
The medium-term scheduler runs more frequently, deciding which process’s  pages to 

swap to and from the swapping device: typically once a second. 
The success of the medium-term scheduler is based on the degree of 
multiprogramming that it can maintain, by keeping as many processes 

“runnable” as possible.
 More processes can remain executable if we reduce the resident set size of  all 

processes.
Makes decisions as to :

- which pages of which processes  need stay resident.

- which pages must be swapped out to make room for other processes. 

In many systems today (those that support mapping virtual address space to secondary storage

other than the swap file), the medium-term scheduler may actually perform the role of the long

term scheduler, by treating binaries as "swapped out processes" upon their execution. In this

way, when a segment of the binary is required it can be swapped in on demand, or "lazyloaded".