Suppose the daytime processing load consists of 55% CPU activity and 45% disk activity. Your customers are complaining that the system is slow. After doing some research, you have learned that you can upgrade your disks to make them 2.5 times as fast as they are currently. You have also learned that you can upgrade your CPU to make it 1.4 as fast. Which would you choose to yield the best performance improvement?

Suppose the daytime processing load consists of 55% CPU activity and 45% disk activity. Your customers are complaining that the system is slow. After doing some research, you have learned that you can upgrade your disks to make them 2.5 times as fast as they are currently. You have also learned that you can upgrade your CPU to make it 1.4 as fast. Which would you choose to yield the best performance improvement?

Operations Research : Applications and Algorithms

4th Edition

ISBN:9780534380588

Author:Wayne L. Winston

Publisher:Wayne L. Winston

Chapter20: Queuing Theory

Section20.10: Exponential Queues In Series And Open Queuing Networks

Problem 11P

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Suppose the daytime processing load consists of 60% CPU activity and 40% disk activity. Your customers are complaining that the system is slow. After doing some research, you learn that you can upgrade your disks for $8,000 to make them 2.5 times as fast as they are currently. You have also learned that you can upgrade your CPU to make it 1.4 times as fast for $5,000. Q. Which would you choose to yield the best performance improvement for the least amount of money?
Suppose the daytime processing load consists of 60% CPU activity and 40% disk activity. Your customers are complaining that the system is slow. After doing some research, you learn that you can upgrade your disks for $8,000 to make them 2.5 times as fast as they are currently. You have also learned that you can upgrade your CPU to make it 1.4 times as fast for $5,000. Q.Which option would you choose if you don’t care about the money, but want a faster system?
Suppose your company has decided that it needs to make certain busy servers 50% faster. Processes in the workload spend 60% of their time using the CPU and 40% on I/O. In order to achieve an overall system speedup of 25%:Q.) How much faster does the disk need to be?
Suppose the daytime processing load consists of 70% CPU activity and 30% disk activity. Your customers are complaining that the system is slow. After doing some research, you have learned that you can upgrade your disks to 2.5 times as fast as they are currently for $5,000 or you can upgrade your CPU to make it 1.5 as fast for $8000. a) Which would you choose to yield the best performance improvement for the least amount of money? b) Which option would you choose if you don't care about the money, but want a faster system?
Suppose your company has decided that it needs to make certain busy servers 30% faster. Processes in the workload spend 70% of their time using the CPU and 30% on I/O. In order to achieve an overall system speedup of 30%: a) How much faster does the CPU need to be? b) How much faster does the disk need to be?
A given computer has a single cache memory (off-chip) with a 2 ns hit time and a 98% hitrate. Its main memory has 40 ns access time.i. What is the computer’s effective access time? ii. If an on-chip cache with a 0.5 ns hit time and a 94% hit rate is added to it, what isthe computer’s new effective access time? iii. How much of a speedup does the on-chip cache give the computer?
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A company that has engaged in a business that requires fast response times has just received a bid for a new system that includes much more storage than was specified in the requirements document. When the company questioned the vendor about the increased storage, the vendor said he was bidding a set of the smallest-capacity disk drives that the company makes. Why didn’t the vendor just bid fewer disks?
In our discussion of the physical aspects of disk performance, we stated that replacing 7,200rpm disks with 10,000rpm disks can bring a 10% to 50% performance improvement. Why would an improvement of only 10% occur? Could it be that no improvement at all would occur? Explain. (Hint: Rotational latency is not the only determining factor of disk performance.)
Suppose that you currently have a computer system with the following two characteristics:There are only three components that determine the overall performance — CPU, memory, and disk.For any given computation, the system spends 30% of the time for CPU, 40% of the time for memory,and 30% of the time for disk. Now suppose that you want to purchase a new system that improves theperformance in the following ways:The memory performance is 4 times faster over your current system, the disk performance is 5 timesfaster over your current system and everything else is the same. Using Amdahl’s Law, calculate theoverall speedup of the new system over your current system.
Suppose that you build a new server with three 1TB disks. a. Which RAID would you choose in the case that most of the disk accesses are for readings and reliabitlity is required? Discuss about capacity, reliabity and performance of your choice. b. Which RAID would you choose to maximize in the case that most of the disk accesses are for writings? Discuss about capacity, reliabity and performance of your choice.
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. Install a faster CPU Install a bigger paging disk. Increase the degree of multiprogramming. Decrease the degree of multiprogramming. Install more main memory. Install a faster hard disk or multiple controllers with multiple hard disks. Add prepaging to the page fetch algorithms. Increase the page size.