Buffering in OS

In Operating Systems I/O operations are one of the most fundamental tasks that is needed to be carried out correctly and with the utmost efficiency. One of the techniques that we can use to ensure the utmost efficiency of the I/O Operations is Buffering. So, Buffering is a process in which the data is stored in a buffer or cache, which makes this stored data more accessible than the original source. Buffer is an area in memory that is used to hold the data that is being transmitted from one place to another and store the data temporarily.

There are a number of data storage devices that are used in a system, like Hard Disks, network devices, pen drives, etc. So, there might be some waiting time faced by the processes or applications that are attempting to access that data from the storage devices. This problem is mainly caused when the devices from where device is slow or have low latency.

This problem is significantly solved using Buffering, as in this process the buffer acts as an intermediate between the storage device and the processes/applications. In this process, the data is already transferred to the Buffer so the data retrieval can be done from it which significantly reduces the waiting time and hence improves the performance of the system.

Types of Buffering in OS

There are mainly three types of Buffering that are used in OS:

1. Single Buffering
2. Double Buffering
3. Circular Buffering

Single Buffering

This is the simplest type of Buffering where only one system buffer is allocated by the Operating System for the system to work with. The producer(I/O device) produces only one block of data in the buffer for the consumer to receive. After one complete transaction of one block of data, the buffer memory again produces the buffer data.

Double Buffering

This is an upgrade over Single Buffering as instead of using one buffer data here two are used. The working of this is similar to the previous one, the difference is that the data is first moved to the first buffer then it is moved to the second buffer. Then retrieved by the consumer end. Here on one hand the data is inserted into one buffer while the data in the other buffer is processed into the other one.

Circular Buffering

Double Buffering is upgraded to this, in this process more than two buffers are used. The mechanism which was used earlier is a bit enhanced here, where one buffer is used to insert the data while the next one of it used to process the data that was earlier inserted. This chain of processing is done until the last buffer in the queue and then the data is retrieved from the last buffer by the consumer. This mechanism is used where we need faster data transfers and more bulky data is transferred.

Function of Buffering in OS

• Synchronization: This process increases the synchronization of different devices that are connected, so the system's performance also improves.
• Smoothening: The input and output devices have different operating speeds and Buffer data block sizes, this process encapsulates the difference and ensures a smooth operation.
• Efficient Usage: Using this processing technique the system overhead and the inefficient usage of the system resources.

How Buffering in OS works?

The different types of Buffering work a little differently as explained in brief earlier, but the baseline working is the same in all the types. This work is given further:

• The operating system starts with allocating memory for creating the Buffers which can be one or more, the size of each one depends on requirements.
• Then the data which is read from the input device is stored in the buffer, as the buffer act as the intermediate stage between the sender and receiver.
• The details of all the buffers that are present in the operating system, details include information like the amount of data stored in the buffer, etc. This information helps the Operating system to manage all the buffers.
• The data is processed and retrieved by the CPU, using this technique the CPU works independently and improves the device's speed. This process helps in the Asynchronous functioning of the CPU in the device.
• Then the Data in the Buffer is Flushed i.e., it is deleted and the memory is freed. The temporary memory space is further used.

Advantages of Buffering

• Buffering significantly reduces the waiting time for a process or application to access a device in the system
• Smoothens the I/O operations between the different devices that are connected to the system.
• Using Buffer number of calls needed for carrying out an operation, so it increases the overall performance of the system.
• Buffering helps cut down on the number of I/O operations that are needed to access the desired data.

Disadvantages of Buffering

• Buffers/Temporary memory that is used to assign data while transferring takes up a lot of memory in a long process.
• Most of the time the exact size of the data going to be transferred is unpredictable so more memory is assigned for every data and most of the time the extra space goes wasted.
• Due to unpredictability sometimes more data is stored on the Buffer than it can store which leads to Buffer Overflow and data corruption.
• In some situations, Buffers can result in a delay between the read and write of the data in the memory and the processing of the data.