Internal vs external fragmentation in Operating Systems - Quick Revision & Key Differences

Recall & Review

beginner

What is internal fragmentation in memory management?

Internal fragmentation happens when fixed-size memory blocks are allocated, but the process uses less space than the block size, leaving unused memory inside the allocated block.

beginner

Define external fragmentation.

External fragmentation occurs when free memory is split into small scattered blocks over time, making it hard to find a large enough continuous block for new processes.

intermediate

How does internal fragmentation differ from external fragmentation?

Internal fragmentation wastes space inside allocated blocks, while external fragmentation wastes space outside allocated blocks due to scattered free memory.

beginner

Give a real-life example of internal fragmentation.

Imagine renting a 10-seat bus for 7 people. The 3 empty seats are like internal fragmentation — space reserved but unused.

intermediate

What is a common technique to reduce external fragmentation?

Techniques like memory compaction rearrange memory contents to combine free spaces into larger blocks, reducing external fragmentation.

Which type of fragmentation occurs when allocated memory blocks have unused space inside them?

A Internal fragmentation

B External fragmentation

C Memory leak

D Paging

Internal fragmentation is unused space inside allocated blocks.

External fragmentation is caused by:

A Fixed-size blocks being too large

B Scattered small free memory blocks

C Processes using less memory than allocated

D Memory leaks

External fragmentation happens when free memory is split into small scattered blocks.

Which method helps reduce external fragmentation?

A Increasing block size

B Allocating fixed-size blocks

C Ignoring free space

D Memory compaction

Memory compaction rearranges memory to combine free spaces.

Internal fragmentation wastes memory because:

A Processes use more memory than allocated

B Free memory is scattered

C Allocated blocks are larger than needed

D Memory is not allocated

Internal fragmentation occurs when allocated blocks are larger than the process needs.

Which fragmentation type can be reduced by using variable-sized memory allocation?

A External fragmentation

B Internal fragmentation

C Both internal and external fragmentation

D None

Variable-sized allocation reduces external fragmentation by fitting memory more closely to process size.

Explain the difference between internal and external fragmentation with examples.

Think about wasted space inside allocated blocks vs scattered free space.

Describe one method to reduce external fragmentation and why it works.

Consider how combining small free spaces helps.