Operating System



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Consider a demand-paged computer system where the degree of mult

Consider a demand-paged computer system where the degree of multiprogramming is currently fixed at four. The system was recently measured to determine utilization of the CPU and the paging disk. The results are one of the following alternatives. For each case, what is happening? Can the degree of multiprogramming be increased to increase the CPU utilization? Is the paging helping? a. CPU...

Consider a demand-paging system with a paging disk that has

Consider a demand-paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one...

Consider a demand-paging system with the following time-measured

Consider a demand-paging system with the following time-measured utilizations: CPU utilization …………….. 20% Paging disk ………………… 97.7% Other I/O devices ………….. 5% For each of the following, say whether it will (or is likely to) improve CPU utilization. Explain your answers. a. Install a faster CPU. b. Install a bigger paging disk. c. Increase the degree of...

Consider a distributed system with two sites, A and B.

Consider a distributed system with two sites, A and B. Consider whether site A can distinguish among the following: a. B goes down. b. The link between A and B goes down. c. B is extremely overloaded, and its response time is 100 times longer than normal. What implications does your answer have for recovery in distributed systems?

Consider a failure that occurs during 2PC for a transaction.

Consider a failure that occurs during 2PC for a transaction. For each possible failure, explain how 2PC ensures transaction atomicity despite the failure.

Consider a file currently consisting of 100 blocks. Assume that

Consider a file currently consisting of 100 blocks. Assume that the file­ control block (and the index block, in the case of indexed allocation) is already in memory. Calculate how many disk I/O operations are required for contiguous, linked, and indexed (single-level) allocation strategies, if, for one block, the following conditions hold. In the contiguous-allocation case, assume that there is...

Consider a file system in which a file can be

Consider a file system in which a file can be deleted and its disk space reclaimed while links to that file still exist. What problems may occur if a new file is created in the same storage area or with the same absolute path name? How can these problems be avoided?

Consider a file system on a disk that has both

Consider a file system on a disk that has both logical and physical block sizes of 512 bytes. Assume that the information about each file is already in memory. For each of the three allocation strategies (contiguous, linked, and indexed), answer these questions: a. How is the logical-to-physical address mapping accomplished in this system? (For the indexed allocation, assume that a file is always...

Consider a file system that uses a modified contiguous-allocatio

Consider a file system that uses a modified contiguous-allocation scheme with support for extents. A file is a collection of extents, with each extent corresponding to a contiguous set of blocks. A key issue in such systems is the degree of variability in the size of the extents. What are the advantages and disadvantages of the following schemes? a. All extents are of the same size, and the size...

Consider a file system that uses inodes to represent files.

Consider a file system that uses inodes to represent files. Disk blocks are 8 KB in size, and a pointer to a disk block requires 4 bytes. This file system has 12 direct disk blocks, as well as single, double, and triple indirect disk blocks. What is the maximum size of a file that can be stored in this file system?