Memory Management in Operating Systems

A function of the operating system (OS) that manages primary memory by moving processes between main and secondary memory during execution.

A memory problem where the available memory blocks are different sizes, creating unused space between blocks.

Memory wastage due to allocated memory blocks being larger than needed by the process, leading to unused space within the block.

Addresses used in source code (variable names, constants, labels).

Addresses calculated during compilation, relative to a starting point.

Final addresses assigned by the loader after loading the program into memory.

The process of assigning memory space to a program/process.

The ability to move a program's location in memory without affecting its execution.

Ensuring each process cannot interfere with other processes' memory.

The act of selecting a job or task to be executed.

A memory management technique that uses both RAM and secondary storage.

Dividing a process into fixed-size pages and allocating memory frames.

Unused memory space within allocated blocks.

Unused memory space between allocated blocks.

An application requiring significant computation, often with long runtimes.

An application performing input/output operations, needing quick responses.

First-Come, First-Served scheduling; jobs execute in the order they arrive.

Processes should be treated equally, preventing any process from being indefinitely delayed.

The algorithm should keep system resources busy, favoring processes utilizing stressed resources.

Fast memory, holding currently used programs and data, volatile.

Non-volatile memory for long-term storage of programs and data. Slower, but cheaper than main memory

Dividing memory into fixed-size blocks at system startup. Processes load into a partition of equal or greater size.

Process is divided into segments loaded together into dynamic partitions; no internal fragmentation

Abstraction of main memory; provides processes a large private memory space.

Unused memory space exists between allocated blocks in memory

Scheduling algorithm that selects processes with the shortest expected remaining processing time.

Scheduling algorithm that chooses the process with the shortest total processing time.

Scheduling algorithm using time slices for processes, interrupting and switching between them regularly.

Time a process enters the system/queue.

Time needed for a process to complete processing.

Time a process completes processing.

Time between process arrival and its completion.

Time a process spends waiting in the queue.

Turnaround time divided by burst time – an efficiency measure of the algorithm

The average time it takes for processes to complete.

Average waiting time across all processes.

A scheduling algorithm that allocates a fixed time slice (quantum) to each process in the ready queue. If a process doesn't complete in its quantum, it's preempted and moved to the back of the queue.

A fixed time period allocated to a process during RR scheduling before being preempted.

An algorithm that allows a running process to be interrupted and another process to take its place.

A preemptive scheduling algorithm that chooses the process with the shortest remaining time next.

The average time taken for a process to complete, from arrival to finish.

The average time a process spends waiting in the ready queue before execution.

A way to give the illusion that multiple processes are running concurrently, by giving them small, fixed time intervals.

A queue of processes waiting to use the CPU.

The amount of time a process needs to execute on the CPU.