Final answer:
Using a demand paging fetch policy in a VM system has pros and cons. It allows for efficient memory usage, but can introduce latency and requires additional bookkeeping.
Step-by-step explanation:
Using a demand paging fetch policy in a VM system has both pros and cons. One of the advantages is that it allows for efficient use of memory. With demand paging, only the necessary pages are loaded into memory, saving space and improving overall performance. This can be particularly beneficial when dealing with large data sets or applications that don't use the entire memory space.
On the other hand, there are also some disadvantages to using a demand paging fetch policy. One drawback is that it can introduce latency or delays when a requested page is not currently in memory and needs to be fetched from the disk. This can impact the responsiveness of the system, especially if there are frequent page faults.
Another con is that demand paging requires additional bookkeeping to keep track of the pages that are currently loaded in memory and those that are on disk. This overhead can consume computational resources and add complexity to the system.