Operating systems are basically known to manage the allocation or the usage of all computer resources and memory!
One of the most popular techniques that is used by the operating system to manage its memory is the technique of swapping.
Swapping in OS is touted as an integral technique to manage the overall memory or to effectively use the memory for all already existing processes.
Though, one question that is commonly asked is; does swapping enhance the overheads of an operating system? If yes, how is it done?
Well, to answer your questions and give you better detailing on the concept of swapping in the OS, we have prepared this blog post.
Without any delay, let’s get started!
Swapping in the Operating System
In the operating system, swapping is defined as a memory management technique which temporarily swaps any process from your main memory so that it will become easily available for the other processes. The basic idea is to improve the utilisation of your main memory.
Though, in secondary memory, the place where a process will be swapped out is known as the swap space. The purpose of swapping in an OS is to present the data in any hard disk or to make it available for use by a program.
A noteworthy thing is that you can only perform the process of swapping when your data is not available in the RAM. Although this process can affect the large part of any system, it would also be helpful for the running of large processes. That is why it is also referred to as the memory compaction.
Let us suppose there are certain processes named P1, P2, P3 and the P4. all of these processes are ready to execute. Though the process P1 and the P2 consumes more memory, any memory may not get available for the processes P3 and P4. In this case, memory would be limited.
But when the memory consuming process will complete heir execution or gets swapped out or get back to the main memory, you can easily start the execution of other processes.
This concept is basically divided into two main categories:
- Swap out: It is a method that removes a process from the RAM by adding it into the hard disk
- Swap in: It is defined as a method that removes any given program from your hard disk by taking it back to either main memory or RAM
Example: the process size of a user is 2048 kb. This is the size of a standard hard disk with the swapping of data at the rate of 1 mbps. You can calculate how long it takes to transfer the data from your main memory to the secondary memory.
Does swapping enhance the overhead of your operating system?
In swapping any idle or the blocked process would be swapped out in the disk. In this case, a process should be ready for the execution when it is brought to the main memory.
But if a process gets blocked, a memory manager may swap out temporarily and get blocked on a disk. Hence, in this case the swap in process may be brought back in your main memory.
Swap space management is considered as the low-level task of any operating system. As the disk space is useful for the extension of your main memory into the virtual memory. The disk access will be considered as slower than that of memory access.
In case of swap space management, we will be only using the disk space. So, it will decrease your system performance. Generally, in all our systems, we need an ideal output, so the goal in this case would be to implement the swap space to provide the virtual memory space.
When any process gets swapped out and then it is swapped again, does this occupy more memory space?
The answer to this question basically depends on the address building. If you do address building in a strategic way, it would be difficult for you to relocate any process in the main memory in order to resume the execution process.
Well, you can change the process in the disk or the backing storage. The disk in this case should have enough space in order to accommodate the process for the users. Here, you will follow two alternatives:
- The first alternative in this case would be to separately swap the file. This may increase your number of files or directory entries
- The second option in this case would be to create a required common swap file. This will be kept on a disk with the location of a swapped out process.
Whatever method you use, you will use a memory space which would be large in any case.
When you learn swapping in OS, you will also learn the term memory compaction. In this case, when a process swaps in and swaps out it will create so many holes in the memory.
How much memory needs to be allocated or swapped?
The answer basically depends on if the process will be created with the big size or if the data segment of a process can grow. If any of the process grows during its runtime, it is good to add some extra space while swapping in or out. This can automatically reduce the overheads in the new space if the process is not fitted.
Additional Learning – Single User Operating System
Another essential operating system concept that every programmer should know is Single User Operating System. Also, defined as the single task operating system, it is basically used by a single user. This type of operating system also allows for the use of personal computers by a user in an efficient way.
Swapping in Os is an essential concept that every computer aspirant should know. In this blog, we tried to explain in detail about swapping in the operating system and how it increases the overheads of an operating system.