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Memory Fit Algorithms
First Fit
First Fit
Advantages
It is fast in processing. As the processor allocates the nearest available memory partition to the job, it is very fast in execution.
Disadvantages
It wastes a lot of memory. The processor ignores if the size of partition allocated to the job is very large as compared to the size of job or not. It just allocates the memory. As a result, a lot of memory is wasted and many jobs may not get space in the memory, and would have to wait for another job to complete.
Next Fit
Next Fit
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Next fit is a modified version of ‘first fit’. It begins as the first fit to find a free partition but when called next time it starts searching from where it left off, not from the beginning. This policy makes use of a roving pointer. The pointer moves along the memory chain to search for a next fit. This helps in, to avoid the usage of memory always from the head (beginning) of the free block chain.
Advantages
Next fit is a very fast searching algorithm and is also comparatively faster than First Fit and Best Fit Memory Management Algorithms.
Disadvantages
It is more difficult to implement than first fit. It can allocate only the next free holes even if previous ones are sufficiently large
Best Fit
Best Fit
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The best fit deals with allocating the smallest free partition which meets the requirement of the requesting process. This algorithm first searches the entire list of free partitions and considers the smallest hole that is adequate. It then tries to find a hole which is close to actual process size needed.
Advantages
Memory utilization is much better than first fit as it searches the smallest free partition first available.
Disadvantages
It is slower and may even tend to fill up memory with tiny useless holes.
Worst Fit
Worst Fit
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Worst Fit allocates a process to the partition which is largest sufficient among the freely available partitions available in the main memory. If a large process comes at a later stage, then memory will not have space to accommodate it
Advantages
Since this process chooses the largest hole/partition, therefore there will be large internal fragmentation. Now, this internal fragmentation will be quite big so that other small processes can also be placed in that leftover partition.
Disadvantages
It is a slow process because it traverses all the partitions in the memory and then selects the largest partition among all the partitions, which is a time-consuming process.
F.A.Q
Frequently Asked Questions
We will be updating the rest of the questions soon
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What are Memory fit Algorithms ?
Memory fit algorithms are algorithms that are used to allocate contiguos memory to processes when there are certain gaps in the memory and some memory is unoccupied by processes and forms holes.
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Why do we need memory fit algorithms ?
We need these algorithms to efficiently allocate contiguos memry to processes and try to avoid fragmentation to some extent.
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What is the advantage of next fit over first fit ?
Next fit tries to address this problem by starting the search for the free portion of parts not from the start of the memory, but from where it ends last time. Next fit is a very fast searching algorithm and is also comparatively faster than First Fit and Best Fit Memory Management Algorithms.