Operating System
Q121.
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 ___________Q122.
Consider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the process's memory requirement. Hence, a new hole of smaller size will be created if allocation is made in any of the existing holes. Which one of the following statement is TRUE?Q123.
A computer has 1000K of main memory. The jobs arrive and finish in the following sequence. Job 1 requiring 200 K arrives Job 2 requiring 350 K arrives Job 3 requiring 300 K arrivesJob 1 finishesJob 4 requiring 120 K arrivesJob 5 requiring 150 K arrivesJob 6 requiring 80 K arrivesAmong best fit and first fit, which performs better for this sequence?Q124.
The Operating System of a computer may periodically collect all the free memory space to form contiguous block of free space. This is called:Q125.
Assume that in a certain computer, the virtual addresses are 64 bits long and the physical addresses are 48 bits long. The memory is word addressable. The page size is 8kB and the word size is 4 bytes. The Translation Look-aside Buffer (TLB) in the address translation path has 128 valid entries. At most how many distinct virtual addresses can be translated without any TLB miss?Q126.
Determine the number of page faults when references to pages occur in the order 1,2,4,5,2,1,2,4. Assume that the main memory can accommodate 3 pages and the main memory already has the pages 1 and 2, with page 1 brought earlier than page 2. (assume LRU i.e., Least-Recently-Used algorithm is applied)Q127.
Consider a process executing on an operating system that uses demand paging. The average time for a memory access in the system is M units if the corresponding memory page is available in memory, and D units if the memory access causes a page fault. It has been experimentally measured that the average time taken for a memory access in the process is X units. Which one of the following is the correct expression for the page fault rate experienced by the process?Q128.
Determine the number of page faults when references to pages occur in the following order: 1, 2, 4, 5, 2, 1, 2, 4 Assume that the main memory can accommodate 3 pages and the main memory already has the pages 1 and 2, with page one having brought earlier than page 2. (LRU page replacement algorithm is used)Q129.
Given reference to the following pages by a program0,9,0,1,8,1,8,7,8,7,1,2,8,2,7,8,2,3,8,3How many page faults will occur if the program has three page frames available to it and uses an optimal replacement?Q130.
A CPU generates 32-bit virtual addresses. The page size is 4 KB. The processor has a translation look-aside buffer (TLB) which can hold a total of 128 page table entries and is 4-way set associative. The minimum size of the TLB tag is: