Partitioning Algorithms

There are various types of Partitioning Algorithm:

  1. First-Fit Algorithm
  2. Next-Fit Algorithm
  3. Best-Fit Algorithm
  4. Worst-Fit Algorithm
  5. Quick-Fit Algorithm

1. First-Fit Algorithm: – In the First-Fit Partitioning algorithm, first, the linked list is scan, and when it finds the first hole which is able to store a process, then scanning is stopped, and we put or load the process into the hole.

In the First-Fit algorithm, there are two partitions. One partition is a hole, and the second partition is used to store the process.

In this algorithm, we have a linked list, and the linked list is maintained on the basis of increasing order of the starting index. The First-Fit algorithm is the easiest type of algorithm among all the algorithms, which we use for partitioning, and it generates a bigger hole.

2. Next-Fit Algorithm: – The Next-Fit algorithm is the same as the First-Fit algorithm, but in the Next-Fit algorithm, the linked list is a scan from the node where it earlier allocated a hole.

In Next-Fit, the entire linked list is not scanned; the linked list is scanned from the next node. As a result, the possibility of finding the hole is more in the remaining part of the list. Thus, it is concluded that First-Fit is better than the Next-Fit. Therefore Next-Fit is rarely used.

3. Best-Fit Algorithm: – In the Best-Fit Algorithm, among all the holes, we find the smallest one so that the size of a process requirement can be accommodated.

Disadvantages of the Best-fit algorithm are:

  1. Best-Fit Algorithm is not the fastest algorithm, and the reason behind that is every time we have to scan the whole list so that the smallest hole can be found that can fulfill the process requirement.
  2. Because the difference between the size of the hole and the size of the process is so small so, the hole which will be produced will also be small, and we cannot use this hole to load any other process. Thus, the hole remains useless. So, Best-Fit is not the best partitioning algorithm among all the algorithms.

4. Worst-Fit Algorithm: – In Worst-Fit Algorithm, every time the whole list is scanned so that the biggest hole can be found that can complete the requirement of the process. Worst-Fit Algorithm generates large holes so that the other processes can be loaded. But despite that, this algorithm is not a suitable approach, and the reason behind that is it is slow because in this algorithm, the entire list is searched again and again.

5. Quick-Fit Algorithm: – In Quick-Fit Algorithm, we maintain a various list related to the size which is frequently used. But practically it is not suggestible. And the reason for that is for this procedure, more time is required to create various lists, and expending the holes to load the process is also a time-consuming task.

Among all the algorithms, the First-Fit algorithm is the best because:

  1. The First-Fit algorithm is easy to implement.
  2. As compared to other algorithms, the First-Fit algorithm takes less time.
  3. The holes produced by the First-Fit algorithm are more prominent, which are helpful to load the other processes later.

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