Problems in Memory ManagementPowerPoint PresentationSlide 3Slide 4Problems in Memory ManagementCS 1550 RecitationOctober 9th, 2002The questions in this slide are from Andrew S. Tanenbaum's textbookpage 264.11. If an instruction takes 10 nsec and a page fault takes and additional n nsec, give a formula for the effective instruction time if page faults occur every k instructions.Consider k instructions: k-1 instructions execution without page fault:10 * (k - 1) nsec1 instuction with page fault:(10 + n) * 1nsecAverage:(10*(k-1) + (10+n)*1) / k = 10 + n/k nsec12. A machine has a 32-bit address space and an 8-KB page. The page is entirely in harware, with one 32-bit word per entry. The page table is copied to the hardware from memory, at one word every 100 nsec. If each process runs for 100 msec (including the time to load the page table), what fraction of the CPU time is devoted to loading the page tables?1 nsec = 1/1,000,000,000 sec1 msec = 1/1,000 secPage size : 8-KB # of offset bits8-KB = 2^13 BytesOffset bits : 13 bitsPage number: 32 – 13 = 19 bitsHow many pages are there?2 ^ 19 = 524288Load time:524288 * 100 nsec = 0.0524288 secCPU time:100 msec = 0.1 secFraction:0.0524288 / 0.1 = 52.4%Real World …32-bit address space == 32-bit word per
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