GATE CSE Memory Management & Virtual Memory – OS Practice Test | Set 1

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).

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.

Paging divides physical memory into fixed-size frames and logical memory into pages, completely eliminating external fragmentation.

Offset d = 350 < Limit (500), which is valid. Physical address = Base + Offset = 2000 + 350 = 2350.

The dirty bit is set by hardware whenever a page is modified. If set, the page must be written back to secondary storage when evicted.