- Top Links
- PrepInsta Home
- OS Home
- Introduction
- CPU Scheduling
- What is Process?
- Process Lifecyle
- Process Control Block
- Process Scheduling
- Context Switching
- CPU Scheduling
- FCFS Scheduling
- SJF (non-preemptive)
- SJF (Preemptive - SRTF)
- Round Robin
- Priority Scheduling
- Convoy Effect
- Scheduler Vs Dispatcher
- Preemptive Vs non
- Preemptive scheduling
- Non preemptive scheduling
- Process Synchronization
- Deadlock
- Popular Algorithms
- Memory Management
- File System
- Others
- Youtube
- Whatsapp Group
- Telegram Group
- Contact us












External Fragmentation


External Fragmentation
Usually, external fragmentation occurs in the case of dynamic or variable sized partitions. Although total space available in the memory is sufficient to execute the process; however, this memory space is not contiguous, which restricts process execution.
Fragmentation
Whenever a process is loaded or removed from the physical memory block, it creates free spaces in the memory, which are commonly known as fragments. These small fragments in the memory cannot be allocated in a contiguous manner to any process as these spaces are not continuous. Consequently, the memory is wasted and cannot be used by another process. This problem is called fragmentation.
External Fragmentation
Usually, external fragmentation occurs in the case of dynamic or variable sized partitions. Although total space available in the memory is sufficient to execute the process; however, this memory space is not contiguous, which restricts process execution.
Learn about internal fragmentation and contrast between internal and external fragmentation.
When it occurs?
When portions of allocated memory are too small to hold any process.
Example
The RAM has a total of 10 kb free space , but it is not contiguous, or is fragmented. If a process with 10 kb size wants to loads on the RAM, then it cannot load because space is not contiguously free.
What is the solution?
The solution for external fragmentation is compaction or shuffle memory contents. In this techniques all the memory contents of memory are shuffled and all free memory is put together in one large block. In order to make compaction feasible, relocation should be dynamic. Also, external fragmentation can be resolved by paging or segmentation mechanisms, which will allow a process to acquire physical memory in a non-contiguous manner.


Read More
- Memory Management Introduction
- Partition Allocation Method
- Buddy- System Allocator
- Paging
- Types of Paging
- Fragmentation
- Mapping Virtual address to Physical Address.
- Virtual Memory
- Demand Paging
- Implementation of Demand paging and page fault
- Segmentation
- Page Replacement Algorithms
- Thrashing
- Belady’s Anomaly
- Static vs Dynamic Loading
- Static vs Dynamic Linking
- Swapping
- Translational Look Aside Buffer
- Process Address Space
- Difference between Segmentation and Paging