Which of the following components contribute to TOTAL DISK ACCESS TIME? (Set 6)
Total Disk Access Time = Seek Time + Rotational Latency + Transfer Time + Controller Overhead.
Which of the following techniques help mitigate or eliminate EXTERNAL FRAGMENTATION?
Compaction moves memory contents to merge free space. Paging uses fixed frames to eliminate external fragmentation entirely.
A process references pages in the order: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5. Using LRU page replacement with 3 page frames initially empty, how many page faults occur? (Question 57)
Tracing LRU with 3 frames: [1] (f1), [1,2] (f2), [1,2,3] (f3), [4,2,3] (f4), [4,1,3] (f5), [4,1,2] (f6), [5,1,2] (f7), [5,1,2] (hit), [5,1,2] (hit), [3,1,2] (f8), [3,4,2] (f9), [3,4,5] (f10). Total = 10 page faults.
In operating system storage architecture, what is defined as 'Controller Overhead'? (Set 34)
Definition of Controller Overhead: The administrative delay imposed by the disk controller logic during an I/O operation.
Consider a system with 64-bit virtual addresses, 4 KB page size, and 8-byte page table entries. In a multi-level paging system where every level page table fits in one page, how many levels of page tables are required? (Question 31)
Page size = 4 KB = $2^12$ B. PTE size = 8 $B = 2^3 B$. Entries per page = $2^12 / 2^3$ = $2^9$ = 512 entries (9 bits per level). Offset = 12 bits. Remaining bits = 64 - 12 = 52 bits. Number of levels = ceil(52 / 9) = 6 levels (or 5 levels for 48-bit canonical physical memory space).