It's UWAweek 45 (2nd semester, 2nd exam week)

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 UWA week 40 (2nd semester, week 10) ↓
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10:56pm Sun 6th Oct, ANONYMOUS

Because of the line "The simulation starts by reading a file where there is a single line of integers separated by blanks" do we need to error check for multiple lines or will it just be assumed we wont be provided with more than one line in the in.txt file?


 UWA week 41 (2nd semester, week 11) ↓
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10:37am Mon 7th Oct, Kristiaan M.

the way I understand the project is that it starts loaded in with the first 2 processes (page numbers 0-7) but because there are 16 pages in disc there is also a copy of process 0 and 1 in disc so instruction 0: bring in least recently used page into RAM from process 0 - currently in disc there are 4 pages in process 0 all with page num 99 and and time step 0 since there is no space in RAM we evict the smallest time step (process 0, time step 0, page num 0) now we add (process 0, time step 0, page num 0) from the disc now we increment the time step this would repeat until the 5th 0, I'm not quite sure what would happen here because in the given sample output they demonstrate that the time step can be greater than 1 but we are also not supposed to modify the disc so I am not sure how this is possible


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1:50pm Mon 7th Oct, Joshua N.

ANONYMOUS wrote:
> Because of the line "The simulation starts by reading a file where there is a single line of > integers separated by blanks" do we need to error check for multiple lines or will it just be assumed we wont be provided with more than one line in the in.txt file?
You would just ignore all lines except the first. However, best practice is to stop processing the file if you detect multiple lines since you would assume the file was corrupted.


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1:54pm Mon 7th Oct, Joshua N.

"Kristiaan Maree" <24*1*7*3@s*u*e*t*u*a*e*u*a*> wrote:
> the way I understand the project is that it starts loaded in with the first 2 processes (page numbers 0-7) but because there are 16 pages in disc there is also a copy of process 0 and 1 in disc
RAM starts empty. You only load processes based on the file.
> so instruction 0: > bring in least recently used page into RAM from process 0 - currently in disc there are 4 pages in process 0 all with page num 99 and and time step 0 > since there is no space in RAM we evict the smallest time step (process 0, time step 0, page num 0)
At instruction 0, there is no process to evict. Since the RAM is empty.
> now we add (process 0, time step 0, page num 0) from the disc > now we increment the time step > > this would repeat until the 5th 0, I'm not quite sure what would happen here because in the given sample output they demonstrate that the time step can be greater than 1 but we are also not supposed to modify the disc so I am not sure how this is possible
Amitava said a process can only be loaded once. So, the fifth 0 would be ignored. I think that was a mistake on Amitava's part, you still need to change the last accessed time.


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6:11pm Mon 7th Oct, Chenjun H.

Hi, Just 2 questions about the assignment, With the global least recently used eviction policy, does this only occur when we try to add a page already in the memory to the memory? Also, since the output is only interested in the ram, what is the purpose of the disk? Can't we simulate the virtual memory just using a ram array, since no information is stored in the pages? Thanks


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7:13pm Mon 7th Oct, Joshua N.

"Chenjun Hou" <23*6*8*9@s*u*e*t*u*a*e*u*a*> wrote:
> Hi, Just 2 questions about the assignment, > > With the global least recently used eviction policy, does this only occur when we try to add a page already in the memory to the memory?
Occurs when RAM is full and you are trying to load a new page into memory. E.g. If page 0 of process zero is in memory and RAM is full and you are trying to load the next page of process 0, then you evict the least recently loaded page of process 0 (in this case page 0) to make room for page 1.
> Also, since the output is only interested in the ram, what is the purpose of the disk? Can't we simulate the virtual memory just using a ram array, since no information is stored in the pages?
Yes, you could, but I'm not sure if that's what Amitava intends. I think he wants you to pass pointers around, which is the only purpose of virtual memory, to store the pointers.
> Thanks
np

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