Process & Memory Management Flashcards

What happens during a context switch?

Answer: The OS saves the state of the current process and loads the state of the next process

A context switch saves the CPU registers and program counter of the outgoing process and restores those of the incoming process.

Which memory protection technique assigns each process a base register and a limit register?

Answer: Base-and-limit registers

Base-and-limit registers define the legal address range for a process, and any access outside that range causes a trap.

What is thrashing in virtual memory systems?

Answer: Excessive paging activity that leaves little time for actual computation

Thrashing occurs when a process spends more time swapping pages in and out than executing instructions.

Which of the following is an example of internal fragmentation?

Answer: Allocated memory that exceeds the process's actual needs within a fixed partition

Internal fragmentation is unused space inside an allocated block when the allocation unit is larger than needed.

In a preemptive scheduling environment, what can forcibly remove a process from the CPU?

Answer: A timer interrupt or higher-priority process arrival

Preemptive scheduling allows the OS to interrupt a running process via a timer or when a higher-priority process becomes ready.

What is the role of the Process Control Block (PCB)?

Answer: To maintain all information the OS needs to manage a process

The PCB stores process state, program counter, registers, memory maps, scheduling info, and I/O status for each process.

Which page replacement policy theoretically produces the fewest page faults but is not implementable in practice?

Answer: Optimal (OPT)

The Optimal algorithm replaces the page that will not be used for the longest time in the future, which requires future knowledge.