GATE 2024 Operating System Foundation Quiz 64

A computer system using segmented paging architecture for virtual memory. The memory is byte addressable. Both virtual and physical address spaces contain 256 KB each. The virtual address space is divided into 8 non-overlapping equal-size segments. The page tables are stored in the main memory and consist of 2-byte page table entries. What is the minimum page size in bytes so that the page table for a segment requires at most one page to store?

Consider a demand paging system with four page frames (initially empty) and LRU page replacement policy. For the following page reference string

7, 2, 7, 3, 2, 5, 3, 4, 6, 7, 7, 1, 5, 6, 1

the page fault rate, defined as the ratio of number of page faults to the number of memory accesses (rounded off to one decimal place) is_________.

Consider a system using paging hardware with a TLB to reduce EMAT. Assume that the entire page table and all the pages are in the physical memory. It takes 30 millisec to search the TLB and 110 millisec to access the physical memory. If the TLB hit ratio is 0.6, the EMAT (in millisec) is _____.[in integer]

During a particular program execution in a pure demand paging system the address generated with 20 records per page with only 1 free main memory frame is recorded are:

150, 199, 209, 480, 290, 599, 400, 780, 690

The number of page faults is _____[in integer]

Assume that we have a demand-paged memory. The page table is held in registers. It takes 8 milliseconds to service a page fault if an empty frame is available or if the replaced page is not modified and 20 milliseconds if the replaced page is modified. Memory-access time is 100 nanoseconds. Assume that the page to be replaced is modified 70 percent of the time. What is the maximum acceptable page-fault rate for an effective access time of no more than 200 nanoseconds?