OS Memory Management

Question 151

Consider a paging system that uses 1-level page table residing in main memory and a TLB for address translation. Each main memory access takes 100 ns and TLB lookup takes 20 ns. Each page transfer to/from the disk takes 5000 ns. Assume that the TLB hit ratio is 95%, page fault rate is 10%. Assume that for 20% of the total page faults, a dirty page has to be written back to disk before the required page is read from disk. TLB update time is negligible. The average memory access time in ns (round off to 1 decimal places) is ___________ . Note - This question was Numerical Type.

• 154.5
• 155
• 755
• 725

Question 152

In the context of operating systems, which of the following statements is/are correct with respect to paging?

• Paging helps solve the issue of external fragmentation
• Page size has no impact on internal fragmentation
• Paging incurs memory overheads
• Multi-level paging is necessary to support pages of different sizes

Question 153

Consider a computer system with a byte-addressable primary memory of size 2³² bytes. Assume the computer system has a direct-mapped cache of size 32 KB (1 KB = 2¹⁰ bytes), and each cache block is of size 64 bytes. The size of the tag field is __________ bits.

• 17
• 18
• 15
• 9