What VM technique allows a now process to start cxecuting without having all pag

Question

What VM technique allows a now process to start cxecuting without having all pages loaded in main mcmory that it will cver need? O demand paging translation look-aside buffer o aptimal page replaccment virtual memory Copy-on write allows a process to O increase the amount of main memory used overal sharc the stack pages cven atter the parcnt process calls other functions O share the code (program) pages O share pages with parent after a fork) before the pages are modified Calculate the page fault rate on a mcmory with 4 frames for the FIFO page replaccment algorithm for the following sequence of page references: 1.23.4.5.13.7,14.5.2.3.7.6.2.5.1.Enter only the percent number For instance, if the result is 55.55%, enter only 55,55, What in NOT a step in handing a pag foul? 0 update the page table entry with the frame number ater the page read operation (from the swap device) O nnda free frane schodule a write oporation for the page that needs to be cxpped ou O check the address reference to see ir it is veld or not What causes the VM subsystem to handle a page fauit? O the process attempts to execute this code "p.100. try from the page tables firds the vid/invali the MMU translatesa virtual address and weer, it reads the page bit to be invalid and thus tripgers a page fauit exception O the process attempts to perform an operation (read/write/executel on a locical adddress that is not permitted by the permission bits in the page table O the MMu trandlates a irtual addross and determines the page numbar is bayond the page table ength segisters A computer uses demand paging irtual memory. Handing a page fault takes & ma and the main memory sccess timc is 2 na. What is the effective access time (in nanoseconds) if the pagc fault rate is 210? Write just the number of nanoseconds The page replacement algorithm that looks into the future is LFU O Optimal MFU LAU FIFO

Explanation / Answer

1. Demand Paging

In demand paging, pages are loaded only when they are needed so we don't need all the pages when starting a process.

2. share pages with parent after a fork() before the pages are modified.

3. 66.67

4. schedule a write operation for the page that needs to be swapped out

5. the MMU translates a virtual address and when it reads the page entry from the page tables find the valid/invalid bit to be invalid and thus triggers a page fault exception

6. 14 nanoseconds

We use the formula Effective Access Time= p*s + (1-p)*m

where p=page fault rate

s=page faut handling time

m=main memory access time

7. Optimal

It replaces that page that will not be used for the longest period of time in future

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