Memory allocation techniques are used to assign blocks of memory based on the request of users. These techniques are important to implement efficient use of the available memory space in the system. These techniques impact the overall performance of the system.Â
In this blog, we will learn about the pros and cons of the memory allocation techniques. This knowledge is responsible for optimising memory usage in operating systems.
What is Memory Allocation?
Memory allocation is the process of reserving computer memory space for specific purposes like storing data or program instructions. It is a fundamental part of computer memory management. It involves determining how much memory or a program that should be located within a computer system.Â
It is an important process for efficient resource utilisation which allows the operating system to assign memory to different processes and applications as needed. There are two major working methods of memory allocation techniques.Â
- Static Allocation: This method is used to allocate available space in a stack like method where the blocks are added and removed in the LIFO order. This is often used for function calls and local variables.Â
- Dynamic Allocation: This method is used to allocate space during runtime allowing programs to request memory as needed. This is useful for programs with variable memory requirements.
Contiguous Memory Allocation TechniquesÂ
Memory allocation techniques are used to decide how data and processes are assigned in the available space in the system memory. These techniques can be categorised in Contiguous and Non-contiguous techniques.Â
Single Partition Allocation
This method helps allocate entire memory to a single process. It was used in very early operating systems such as MS-DOS, etc. It does not allow multitasking.Â
Multiple Partition Allocation
This allocation technique is used to divide the memory into fixed and variable size partitions.Â
A. Fixed PartitionÂ
This is also known as static allocation which divides the partition into fixed size. It however leads to internal fragmentation when the process is smaller than the partition where unused space is wasted.Â
B. Dynamic Memory Allocation
In this method partitions in the memory are created dynamically based on process size. It however suffers from external fragmentation due to small gaps left between processes. It uses compaction to defragment memory.
Read more: Process Management In Operating SystemÂ
Dynamic Memory AllocationÂ
In dynamic memory allocation there can be variable partitioning of the memory. Let us see one by one.Â
- First Fit: The first fit locates the first available block that is large enough. It is fast but may cause fragmentation.
- Best Fit: The Best fit locates the smallest available block that fits the process. It reduces waste but is slower.
- Worst Fit: The Worst fit locates the largest available block, leaving large gaps. It can increase fragmentation.
Non-Contiguous Memory Allocation Techniques
In this method of memory allocation techniques each process get a single contiguous block of memory with memory scattered to non contiguous locations in the memory.
Paging
Paging is a method in which memory is divided into fixed size blocks called pages and frames i,e. Memory side and pages are on the process side. Pages can easily be mapped using the page table.Â
This method can easily eliminate external fragmentation and ensure no unused space wastage. However, it might cause internal fragmentation if the page size is too large.
Segmentation
This method is used to divide memory into variable size segments based on the logical divisions such as stack, heap, or code. Here, each segment is allocated separately which avoid internal fragmentation to take place. However, this method might cause external fragmentation in the memory.
Virtual Memory Allocation Techniques
Virtual Memory allocation technique is a process in which we use secondary storage as an extension of RAM for storage. The OS swaps data between RAM and disk when needed which allow large applications to run on the limited RAM.Â
Whenever you need the data for any operation you can transfer it from secondary storage space to the RAM easily. It is implemented using paging and demand paging. To know more about Virtual Memory Allocation Techniques Click Here.
Why Do We Need Memory Allocation Techniques?
There are more than one reason which satisfies the need of using effective memory allocation techniques in our operating system. Let us check some of the major benefits of them below.
- We need memory allocation to avoid wastage of memory due to fragmentation happening in memory.
- It ensures that each process gets the necessary space without making any conflicts.
- It is an important set of steps to avoid fragmentation issues i,e. External and internal fragmentation.
- With proper allocation we can prevent processes from overwriting each other’s memory space which can lead to conflicts for memory.
- With memory allocation techniques in place faster process execution and reduction of CPU overhead can be made possible.
- It is very much useful for the modern day variable workloads which require dynamic memory allocation techniques.Â
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Memory Allocation Techniques FAQs
Q1. What are Memory Allocation techniques?
Ans: Memory allocation is the process of reserving computer memory space for specific purposes like storing data or program instructions. It is a fundamental part of computer memory management.
Q2. What are different types of memory allocation techniques?
Ans: There are many types of memory allocation techniques however the main classification are contiguous memory allocation, non-contiguous memory allocation and virtual memory allocation techniques.
Q3. What is Segmentation?
Ans: The segmentation method is used to divide memory into variable size segments based on the logical divisions such as stack, heap, or code. Here, each segment is allocated separately which avoid internal fragmentation to take place.
Q4. Does Fixed partition have external fragmentation?
Ans: No fixed partition eliminates external fragmentation however it can lead to internal fragmentation in the memory leading to wastage of space in the memory.
