Memory Management
Q11.
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?Q12.
The Operating System of a computer may periodically collect all the free memory space to form contiguous block of free space. This is called:Q13.
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?Q14.
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)Q15.
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?Q16.
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)Q17.
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?Q18.
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:Q19.
In which one of the following page replacement algorithms it is possible for the page fault rate to increase even when the number of allocated frames increases?Q20.
Let the page fault service time be 10 ms in a computer with average memory access time being 20 ns. If one page fault is generated for every 10^6 memory accesses, what is the effective access time for the memory?