[Solved] A system using the buddy system has free blocks of sizes 8KB, 16KB, and 32KB.... Which blocks will be split or merged to satisfy this request, and what fragmentation type is most likely to occur? | Operating Systems

Operating Systems - Internal vs External Fragmentation - Compaction & Buddy System

A system using the buddy system has free blocks of sizes 8KB, 16KB, and 32KB. A request for 20KB arrives. Which blocks will be split or merged to satisfy this request, and what fragmentation type is most likely to occur?

AMerge 8KB and 16KB blocks to form 24KB; external fragmentation likely

BSplit the 16KB block into two 8KB buddies; internal fragmentation likely

CSplit the 32KB block into two 16KB buddies; internal fragmentation likely

DUse the 32KB block without splitting; external fragmentation likely

Step-by-Step Solution

Solution:

Step 1: Identify suitable block
Request is 20KB; smallest block ≥20KB is 32KB.
Step 2: Buddy system splitting
Splitting 32KB block into two 16KB blocks results in blocks too small for 20KB request; so the 32KB block is allocated without splitting.
Step 3: Fragmentation type
Allocating 32KB for 20KB request causes internal fragmentation (unused space inside allocated block).
Step 4: Evaluate options
Merge 8KB and 16KB blocks to form 24KB; external fragmentation likely is invalid as buddy system merges only buddies of same size; Split the 32KB block into two 16KB buddies; internal fragmentation likely is incorrect because splitting 32KB into 16KB blocks is insufficient; Split the 16KB block into two 8KB buddies; internal fragmentation likely splits smaller block insufficient for 20KB; Use the 32KB block without splitting; external fragmentation likely incorrectly states external fragmentation; the correct behavior is to allocate 32KB block without splitting, causing internal fragmentation.
Final Answer:
Option C -> Option C
Quick Check:
Buddy system allocates next power-of-two block; internal fragmentation occurs when block size exceeds request size [OK]

Quick Trick: Buddy system allocates blocks in powers of two; internal fragmentation arises when request size is less than block size [OK]

Common Mistakes:

MISTAKES

Thinking buddy system merges different sized blocks
Ignoring internal fragmentation from block size rounding

Trap Explanation:

PITFALL

Candidates confuse merging rules and underestimate internal fragmentation from block size rounding.

Interviewer Note:

CONTEXT

Tests understanding of buddy system splitting and fragmentation consequences.

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Solution Trace

More Operating Systems Quizzes

Which blocks will be split or merged to satisfy this request, and what fragmentation type is most likely to occur?

Step 1: Identify suitable block

Step 2: Buddy system splitting

Step 3: Fragmentation type

Step 4: Evaluate options

Final Answer:

Quick Check:

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