Key Takeaways
- Internal fragmentation occurs when allocated space have leftover unused memory within a block, wasting storage within allocated areas.
- External fragmentation involves free memory scattered in small chunks across the system, making it hard to find contiguous space for new allocations.
- While internal fragmentation can be minimized through better allocation strategies, external fragmentation requires defragmentation to reclaim space.
- Internal fragmentation tends to happen with fixed-sized memory allocations, whereas external fragmentation are common in systems with dynamic memory allocation.
- Understanding these fragmentation types helps in choosing appropriate memory management techniques to optimize system performance.
What is Internal Fragmentation?
Internal fragmentation happens when memory blocks are allocated in fixed sizes, but the process only needs part of the space, leaving unused memory inside the block.
This results in wasted storage that cannot be used for other processes, even if there is enough total free memory in the system. It occurs in systems which allocate memory in chunks.
Fixed-sized memory blocks
Memory are divided into blocks of predefined sizes, which can lead to leftover space within each block if the process needs less. This leftover space becomes internal fragmentation.
For example, if a process needs 60 KB but the block size is 64 KB, then 4 KB remains unused inside which block. This unused space can’t be allocated to other processes.
Impact on system efficiency
Internal fragmentation reduces the effective memory available for processes, leading to inefficient use of memory resources. It can cause performance bottlenecks in high-demand systems.
Systems that rely on fixed-size allocations may waste large portions of memory, especially if many small processes are running simultaneously.
Memory wastage
This wastage can pile up over time, decreasing the amount of usable memory, and forcing systems to use slower storage options or swap space. Although incomplete. It complicates memory management tasks.
Over-allocating memory to prevent fragmentation can also be a problem, as it consumes more space than needed, reducing overall system capacity.
Examples in real-world systems
Operating systems using fixed partitioning or certain file systems can exhibit internal fragmentation, especially when handling small files or tasks requiring less space.
Memory management in embedded systems also faces internal fragmentation issues, as resource constraints make fixed allocations common.
What is External Fragmentation?
External fragmentation occurs when free memory is broken into small, non-contiguous pieces scattered across the system, even if total free space is enough for a new process.
This problem makes it difficult to allocate large blocks of memory despite having enough total free space, leading to inefficient memory use.
Scattered free memory
Over time, as processes allocate and free memory, small gaps emerge between used blocks, preventing large allocations. These gaps are external fragments.
For example, a system may have several small free spaces that add up to sufficient memory, but because they’re fragmented, a large new process cannot be loaded.
Causes of external fragmentation
Repeated allocations and deallocations cause free memory to become unevenly distributed. Fragmentation worsens especially with dynamic memory systems.
Memory holes develop when processes are terminated, but their freed spaces are not merged with adjacent free blocks, creating scattered fragments.
Difficulty in large memory allocations
External fragmentation makes it hard to find continuous memory blocks needed by large applications or databases. Although incomplete. This can cause delays or failure to allocate memory.
Systems may need to perform defragmentation or compact memory to allow large data sets or applications to run smoothly.
Real-world examples
File systems that manage disk space dynamically face external fragmentation, especially after deleting large files, leaving small unusable gaps.
In virtual memory systems, external fragmentation can cause delays in swapping processes in and out, affecting overall system performance.
Comparison Table
Below are a table contrasting internal and external fragmentation across key aspects:
| Aspect | Internal Fragmentation | External Fragmentation |
|---|---|---|
| Definition | Unused memory inside allocated blocks due to fixed sizes | Free memory scattered in small chunks, unable to fit large requests |
| Causes | Fixed-sized memory blocks allocation | Repeated allocation and deallocation of varied sizes |
| Mitigation Techniques | Using variable-sized allocations or padding | Memory compaction or defragmentation |
| Impact on Memory | Wastes space within allocated regions | Prevents large memory blocks from being allocated |
| Typical Occurrence | In fixed partitioning systems or embedded systems | In systems with dynamic memory allocation, file systems |
| Detection Method | Monitoring unused space in blocks | Analyzing free space patterns for fragmentation |
| Effect on Performance | Can cause underutilization, slowdowns | Can cause delays or failure to allocate large requests |
| System Type Affected | Memory management in fixed partition systems | File storage systems, virtual memory systems |
| Size of Wasted Space | Relatively small per block, accumulates over time | Large gaps can exist, severely limiting allocations |
| Example | Memory block of 64 KB allocated for 60 KB process | Deleting multiple files leaving small free gaps scattered |
Key Differences
- Internal fragmentation is clearly visible in wasted space within fixed memory blocks allocated to processes, while external fragmentation is seen as scattered free spaces across the memory.
- Internal fragmentation revolves around inefficient use of allocated memory, whereas external fragmentation concerns the difficulty in finding large enough free contiguous spaces.
- Internal fragmentation is more prominent in systems with fixed-size allocations, but external fragmentation occurs more in systems with dynamic allocations.
- External fragmentation relates to the inability to utilize free space effectively, whereas internal fragmentation is about leftover unused space within allocated blocks.
FAQs
How does fragmentation impact system upgrade processes?
Fragmentation makes it harder to allocate large memory blocks needed during upgrades, possibly requiring system downtime for defragmentation or reallocation procedures, delaying improvements or patches.
Can fragmentation lead to increased energy consumption?
Yes, especially with external fragmentation, additional processing for defragmentation or swapping increases power usage, impacting battery life in portable devices.
Are there specific hardware components more affected by fragmentation?
Storage drives and memory modules experience more issues with fragmentation, as scattered data or free space reduces efficiency and can cause longer access times.
What role does fragmentation play in cloud computing environments?
Fragmentation complicates resource allocation, leading to underutilized storage and memory pools, which can increase costs and reduce overall system responsiveness in shared environments.