这是一篇澳洲的计算机系统和网络的容量规划限时测试程序代写
Instructions:
- Time allowed – 2 hours, plus 15 minutes.
- Total number of questions to be answered – 10. Answer all questions.
- Total marks available – 100 marks, worth 50% of the total marks for the course.
- Marks available for each question are shown in the exam.
- Students are advised to read all of the examination questions before attempting to answer the questions.
- This exam cannot be copied, forwarded, or shared in any way.
- Students are reminded of the UNSW rules regarding Academic Integrity and Plagiarism.
- Your work will be saved periodically throughout the exam and will be automatically submitted when the test ends provided you are connected to the internet.
- DO NOT submit this sample exam. If you submit this exam, you will no longer be able to access it.
- In answering all the questions, it is important for you to show your intermediate steps and what arguments you have made to obtain the results. You need to note that both the intermediate steps and the arguments carry marks. Please note that we are not just interested in whether you can get the final numerical answer right, but we are more interested to find out whether you understand the subject matter. We do that by looking at your intermediate steps and the arguments that you have made to obtain the answer. Thus, if you can show us the perfect intermediate steps and the in-between arguments but got the numerical values wrong for some reason, we will still award you marks for having understood the subject matter.
- You may use these formatting shortcuts in your answers if you want:
- Instead of subscript P123 , you may write P_{123} etc.
- Instead of superscript 106, you may write 10^6 etc.
- Instead of the Greek alphabet λ, you may write lambda etc.
- This is an open-book and open-web examination. Consider a computer system which is used to support a website. The system, depicted in the figure below, consists of three devices: one distributor and two servers. Each device consists of a processor and a buffer.
When an HTTP request arrives at the website, it is first processed by the distributor. The request is then sent to one of the two servers for processing.
With probability 0.4, the request is sent to Server 1. With probability 0.6, the request is sent to Server 2. Once a request is processed by either server, the request is completed and the HTTP response is sent to the user.
During the routine operation of the web site, the following measurements are collected:
The web site is found to process 72,000 HTTP requests in one hour.
The average number of HTTP requests in the distributor is 0.2.
For Server 1, there is on average 3.2 HTTP requests waiting in the buffer for processing, and each HTTP request requires a service time of 100 milliseconds.
For Server 2, there is on average 8.1 HTTP requests waiting in the buffer for processing, and each HTTP request requires a service time of 75 milliseconds.Question 1
Read the panel on the left and then answer the questions below.
This question consists of 3 parts: Parts (a), (b) and (c).
Part (a)
What is the utilization of Server 1?
Part (b)
What is the average waiting time of Server 1?
Part (c)
What is the average response time of Server 1?
Consider a non-preemptive priority single-server queueing system with 2 classes of jobs. The two classes of jobs will be referred to as Class A and Class B where the jobs in Class A have non-preemptive priority over the jobs in Class B. Jobs from Class A obey Poisson arrival with mean arrival rate and exponential service time distribution with mean service time . Jobs from Class B obey Poisson arrival with mean arrival rate and exponential service time distribution with mean service time . You can assume that the following 4 probability distributions are independent of each other: inter-arrival time distribution of Class A jobs, inter-arrival time distribution of Class B jobs and service time distributions of Class B jobs.
The queueing system consists of 2 queues, which will be referred to as Queue A and Queue B in this question. Each queue consists of 1 buffer space.
Assuming that Queue A is used to buffer jobs from Class A alone and Queue B is used to buffer jobs from Class B alone. This non-preemptive priority queueing system can be modelled by a continuous-time Markov chain. The state of the
Markov chain is the three tuple（nA,nB,nS）where nA is the number of jobs in Queue A,nB is the number of jobs in Queue B, and nS is number of jobs in the server.
程序辅导定制C/C++/JAVA/安卓/PYTHON/留学生/PHP/APP开发/MATLAB
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