It's UWAweek 50

help2002

This forum is provided to promote discussion amongst students enrolled in CITS2002 Systems Programming.
Please consider offering answers and suggestions to help other students! And if you fix a problem by following a suggestion here, it would be great if other interested students could see a short "Great, fixed it!"  followup message.
Displaying the 4 articles in this topic
Showing 4 of 834 articles.
Currently 6 other people reading this forum.


 UWA week 43 (2nd semester, study break) ↓
SVG not supported

Login to reply

👍?
helpful
10:21pm Thu 24th Oct, ANONYMOUS

Hello, I am reposting my question as it seems my question has been missed. Could someone please clarify or help with my understanding please? The question is below Hi all! I'm currently on Past Exam 2021 Question 5. I'm wondering if for """ A computer system employing 32-bit addresses implements virtual memory using a two-level page table. The right-most 10 bits of each virtual address are used to specify the required offset within a page. The left-most 8 bits are used to index the primary (or root) page table, and the remaining ‘middle’ 14 bits are used for the secondary page tables. (a) What is the page size in this machine? (b) What is the size of the primary page table? (c) What is the number of secondary page tables? (d) Explain why it is sufficient to keep only the primary page table in the RAM. """ (b) What is the size of the primary page table? Does it want the amount of entries which would be 2^8 = 256 entries or would it be 2^8 x 4 bytes = 1024 bytes (c) What is the number of secondary page tables? Would this just be 256 since each entry in primary would mean 1 secondary page? Thanks for the help!


SVG not supported

Login to reply

👍?
helpful
7:30pm Fri 25th Oct, Amitava D.

ANONYMOUS wrote:
> Hello, I am reposting my question as it seems my question has been missed. Could someone please clarify or help with my understanding please? The question is below > > > Hi all! I'm currently on Past Exam 2021 Question 5. I'm wondering if for > > """ > A computer system employing 32-bit addresses implements virtual memory > using a two-level page table. > The right-most 10 bits of each virtual address are used to specify the required > offset within a page. The left-most 8 bits are used to index the primary (or > root) page table, and the remaining ‘middle’ 14 bits are used for the secondary > page tables. > (a) What is the page size in this machine? > (b) What is the size of the primary page table? > (c) What is the number of secondary page tables? > (d) Explain why it is sufficient to keep only the primary page table in the > RAM. > """ > > > (b) What is the size of the primary page table? > Does it want the amount of entries which would be 2^8 = 256 entries or would it be 2^8 x 4 bytes = 1024 bytes > > (c) What is the number of secondary page tables? > Would this just be 256 since each entry in primary would mean 1 secondary page? > > Thanks for the help!
page size is 2^10 primary page table size is 2^8 There are 2^14 secondary page tables, each entry of the primary page table holds the starting address of a secondary page table. One can bring the secondary page tables on demand (the secondary page tables are paged)


SVG not supported

Login to reply

👍?
helpful
7:48pm Fri 25th Oct, ANONYMOUS

"Amitava Datta" <am*t*v*.*a*t*@*w*.*d*.*u> wrote:
> ANONYMOUS wrote: > > > Hello, I am reposting my question as it seems my question has been missed. Could someone please clarify or help with my understanding please? The question is below > > > > > > Hi all! I'm currently on Past Exam 2021 Question 5. I'm wondering if for > > > > """ > > A computer system employing 32-bit addresses implements virtual memory > > using a two-level page table. > > The right-most 10 bits of each virtual address are used to specify the required > > offset within a page. The left-most 8 bits are used to index the primary (or > > root) page table, and the remaining ‘middle’ 14 bits are used for the secondary > > page tables. > > (a) What is the page size in this machine? > > (b) What is the size of the primary page table? > > (c) What is the number of secondary page tables? > > (d) Explain why it is sufficient to keep only the primary page table in the > > RAM. > > """ > > > > > > (b) What is the size of the primary page table? > > Does it want the amount of entries which would be 2^8 = 256 entries or would it be 2^8 x 4 bytes = 1024 bytes > > > > (c) What is the number of secondary page tables? > > Would this just be 256 since each entry in primary would mean 1 secondary page? > > > > Thanks for the help! > page size is 2^10 > primary page table size is 2^8 > There are 2^14 secondary page tables, each entry of the primary page table holds the starting address of a secondary page table. > One can bring the secondary page tables on demand (the secondary page tables are paged)
Thank you for your reply, I'd like to ask why there'd be 2^14 secondary page tables instead of the size of secondary page table being 2^14. As I understand, primary page table will hold the address to a single secondary page table. Perhaps I'm mistaken


SVG not supported

Login to reply

👍?
helpful
1:26pm Sat 26th Oct, ANONYMOUS

"Amitava Datta" <am*t*v*.*a*t*@*w*.*d*.*u> wrote:
> There are 2^14 secondary page tables
Pretty sure this is not correct. The primary page table size is 2^8=256, where each of these 256 entries points to a secondary page table. Therefore there are 2^8=256 secondary page tables, one for each index of the primary page table. Each of these secondary page tables then has 2^14=16384 entries, each one pointing to a page, so each secondary page table is of size 2^14.

The University of Western Australia

Computer Science and Software Engineering

CRICOS Code: 00126G
Written by [email protected]
Powered by history
Feedback always welcome - it makes our software better!
Last modified  8:08AM Aug 25 2024
Privacy policy