01-20-2016, 06:20 PM
Question 1 Marks 25
Consider a paging system with a page table stored in memory.
(a) Marks 5
If a memory reference takes 200 nanoseconds, how long does a paged reference take (reference is retrieved from page table in memory and then program data is retrieved from memory) Assume all pages are in memory?
(b) Marks 10
If we add a Translation Look-aside Buffer (TLB), and 75 percent of all page-table references are found in the TLB i.e. the TLB hit ratio is 75%, what is the effective memory reference time on average? (Assume that finding a page table entry in TLB takes 10 nanoseconds, if the entry is there.) Assume all pages are in memory.
© Marks 10
What is the effective memory reference time if the hit ratio for TLB is 70%, the hit ratio for memory is 20%, and 10% of the time we must go out to the disk to load the faulted page in memory, where context switching, disk transfer time takes 100 m seconds.
Question 2 Marks 10
Consider a file that is 1000 disk blocks in size. Assume that a disk block is to be appended to the end of the file, which shall cause the file size to grow to 1001 blocks. How many disks read and write operations are required to update the file and the file descriptor? Assume that the file is stored as a linked list with the pointer to the next file block stored at the end of each block. Also assume that both the file and the file descriptor are initially on disk and that file buffer cache is empty. How will your answer change if a multi-level index scheme is used instead of a linked file organization?
For this case assume that the file descriptor (i-node) can store 1000 disk block entries and each indirect block has 1024 entries ==> block 1001 is in the 1st level indirect block
Question 3
Read the attached paper titled “Time-Sharing Time Warp via Lightweight Operating System Support” and answer the following questions.
a) Marks 7
How the proposed solution is based on an ad-hoc kernel module for Linux, which implements a fine grain timer-interrupt mechanism.
b) Marks 8
Describe the effectiveness of the proposed idea in terms of improvements of the execution speed of Time Warp simulations on multi-core machines.
What is the effective memory reference time if the hit ratio for TLB is 70%, the hit ratio for memory is 20%, and 10% of the time we must go out to the disk to load the faulted page in memory, where context switching, disk transfer time takes 100 m seconds.
Consider a paging system with a page table stored in memory.
(a) Marks 5
If a memory reference takes 200 nanoseconds, how long does a paged reference take (reference is retrieved from page table in memory and then program data is retrieved from memory) Assume all pages are in memory?
(b) Marks 10
If we add a Translation Look-aside Buffer (TLB), and 75 percent of all page-table references are found in the TLB i.e. the TLB hit ratio is 75%, what is the effective memory reference time on average? (Assume that finding a page table entry in TLB takes 10 nanoseconds, if the entry is there.) Assume all pages are in memory.
© Marks 10
What is the effective memory reference time if the hit ratio for TLB is 70%, the hit ratio for memory is 20%, and 10% of the time we must go out to the disk to load the faulted page in memory, where context switching, disk transfer time takes 100 m seconds.
Question 2 Marks 10
Consider a file that is 1000 disk blocks in size. Assume that a disk block is to be appended to the end of the file, which shall cause the file size to grow to 1001 blocks. How many disks read and write operations are required to update the file and the file descriptor? Assume that the file is stored as a linked list with the pointer to the next file block stored at the end of each block. Also assume that both the file and the file descriptor are initially on disk and that file buffer cache is empty. How will your answer change if a multi-level index scheme is used instead of a linked file organization?
For this case assume that the file descriptor (i-node) can store 1000 disk block entries and each indirect block has 1024 entries ==> block 1001 is in the 1st level indirect block
Question 3
Read the attached paper titled “Time-Sharing Time Warp via Lightweight Operating System Support” and answer the following questions.
a) Marks 7
How the proposed solution is based on an ad-hoc kernel module for Linux, which implements a fine grain timer-interrupt mechanism.
b) Marks 8
Describe the effectiveness of the proposed idea in terms of improvements of the execution speed of Time Warp simulations on multi-core machines.
What is the effective memory reference time if the hit ratio for TLB is 70%, the hit ratio for memory is 20%, and 10% of the time we must go out to the disk to load the faulted page in memory, where context switching, disk transfer time takes 100 m seconds.
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