Answer:
We have six memory partitions, let label them:
100MB (F1), 170MB (F2), 40MB (F3), 205MB (F4), 300MB (F5) and 185MB (F6).
We also have six processes, let label them:
200MB (P1), 15MB (P2), 185MB (P3), 75MB (P4), 175MB (P5) and 80MB (P6).
Using First-fit
- P1 will be allocated to F4. Therefore, F4 will have a remaining space of 5MB from (205 - 200).
- P2 will be allocated to F1. Therefore, F1 will have a remaining space of 85MB from (100 - 15).
- P3 will be allocated F5. Therefore, F5 will have a remaining space of 115MB from (300 - 185).
- P4 will be allocated to the remaining space of F1. Since F1 has a remaining space of 85MB, if P4 is assigned there, the remaining space of F1 will be 10MB from (85 - 75).
- P5 will be allocated to F6. Therefore, F6 will have a remaining space of 10MB from (185 - 175).
- P6 will be allocated to F2. Therefore, F2 will have a remaining space of 90MB from (170 - 80).
The remaining free space while using First-fit include: F1 having 10MB, F2 having 90MB, F3 having 40MB as it was not use at all, F4 having 5MB, F5 having 115MB and F6 having 10MB.
Using Best-fit
- P1 will be allocated to F4. Therefore, F4 will have a remaining space of 5MB from (205 - 200).
- P2 will be allocated to F3. Therefore, F3 will have a remaining space of 25MB from (40 - 15).
- P3 will be allocated to F6. Therefore, F6 will have no remaining space as it is entirely occupied by P3.
- P4 will be allocated to F1. Therefore, F1 will have a remaining space of of 25MB from (100 - 75).
- P5 will be allocated to F5. Therefore, F5 will have a remaining space of 125MB from (300 - 175).
- P6 will be allocated to the part of the remaining space of F5. Therefore, F5 will have a remaining space of 45MB from (125 - 80).
The remaining free space while using Best-fit include: F1 having 25MB, F2 having 170MB as it was not use at all, F3 having 25MB, F4 having 5MB, F5 having 45MB and F6 having no space remaining.
Using Worst-fit
- P1 will be allocated to F5. Therefore, F5 will have a remaining space of 100MB from (300 - 200).
- P2 will be allocated to F4. Therefore, F4 will have a remaining space of 190MB from (205 - 15).
- P3 will be allocated to part of F4 remaining space. Therefore, F4 will have a remaining space of 5MB from (190 - 185).
- P4 will be allocated to F6. Therefore, the remaining space of F6 will be 110MB from (185 - 75).
- P5 will not be allocated to any of the available space because none can contain it.
- P6 will be allocated to F2. Therefore, F2 will have a remaining space of 90MB from (170 - 80).
The remaining free space while using Worst-fit include: F1 having 100MB, F2 having 90MB, F3 having 40MB, F4 having 5MB, F5 having 100MB and F6 having 110MB.
Explanation:
First-fit allocate process to the very first available memory that can contain the process.
Best-fit allocate process to the memory that exactly contain the process while trying to minimize creation of smaller partition that might lead to wastage.
Worst-fit allocate process to the largest available memory.
From the answer given; best-fit perform well as all process are allocated to memory and it reduces wastage in the form of smaller partition. Worst-fit is indeed the worst as some process could not be assigned to any memory partition.