Given six memory partitions of 300 KB, 600 KB, 350 KB, 200 KB, 750 KB, and 125 KB (in order), how would the first-fit, best-fit, and worst-fit algorithms place processes of size 115 KB, 500 KB, 358 KB, 200 KB, and 375 KB (in order) ? Rank the algorithms in terms of how efficiently they use memory.

Question

Joselyn Bird

Computers & Technology

6 December, 00:33

Given six memory partitions of 300 KB, 600 KB, 350 KB, 200 KB, 750 KB, and 125 KB (in order), how would the first-fit, best-fit, and worst-fit algorithms place processes of size 115 KB, 500 KB, 358 KB, 200 KB, and 375 KB (in order) ? Rank the algorithms in terms of how efficiently they use memory.

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Dante Gutierrez · Answer 1

In terms of efficient use of memory: Best-fit is the best (it still have a free memory space of 777KB and all process is completely assigned) followed by First-fit (which have free space of 777KB but available in smaller partition) and then worst-fit (which have free space of 1152KB but a process cannot be assigned). See the detail in the explanation section.

Explanation:

We have six free memory partition: 300KB (F1), 600KB (F2), 350KB (F3), 200KB (F4), 750KB (F5) and 125KB (F6) (in order).

Using First-fit

First-fit means you assign the first available memory that can fit a process to it.

115KB will fit into the first partition. So, F1 will have a remaining free space of 185KB (300 - 115). 500KB will fit into the second partition. So, F2 will have a remaining free space of 100KB (600 - 500) 358KB will fit into the fifth partition. So, F5 will have a remaining free space of 392KB (750 - 358) 200KB will fit into the third partition. So, F3 will have a remaining free space of 150KB (350 - 200) 375KB will fit into the remaining partition of F5. So, F5 will a remaining free space of 17KB (392 - 375)

Using Best-fit

Best-fit means you assign the best memory available that can fit a process to the process.

115KB will best fit into the last partition (F6). So, F6 will now have a free remaining space of 10KB (125 - 115) 500KB will best fit into second partition. So, F2 will now have a free remaining space of 100KB (600 - 500) 358KB will best fit into the fifth partition. So, F5 will now have a free remaining space of 392KB (750 - 358) 200KB will best fit into the fourth partition and it will occupy the entire space with no remaining space (200 - 200 = 0) 375KB will best fit into the remaining space of the fifth partition. So, F5 will now have a free space of 17KB (392 - 375)

Using Worst-fit

Worst-fit means that you assign the largest available memory space to a process.

115KB will be fitted into the fifth partition. So, F5 will now have a free remaining space of 635KB (750 - 115) 500KB will be fitted also into the remaining space of the fifth partition. So, F5 will now have a free remaining space of 135KB (635 - 500) 358KB will be fitted into the second partition. So, F2 will now have a free remaining space of 242KB (600 - 358) 200KB will be fitted into the third partition. So, F3 will now have a free remaining space of 150KB (350 - 200) 375KB will not be assigned to any available memory space because none of the available space can contain the 375KB process.