【COMP9334】Capacity Planning of Computer Systems and Networks

Due 5:00pm, Fri 17 March 2023 (Friday Week 5)

Change log and version info

Updates, changes and clarifications will appear in this box.

• Version 1.01 (7 March 2023) revises the wording in Question 1.

• Version 1.00 issued on 27 February 2023

Instructions

(1) There are 3 questions in this assignment. Answer all questions.

(2) The total mark for this assignment is 20 marks.

(3) The submission deadline is 5:00pm Friday 17 March 2023. Submissions made after the

deadline will incur a penalty of 5% per day. Late submissions will only be accepted

until 5:00pm Wednesday 22 March 2023, after which no submissions will be accepted.

(4) In answering the questions, it is important for you to show your intermediate steps and

state 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, we are more inter-

ested 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 get the numerical values wrong for some reason, we will still award you marks for

having understood the subject matter.

You can take a look at the solution to revision problems to get some ideas the level of

explanation that is required.

(5) If you use a computer program to perform any part of your work, you must submit the

program or you lose marks for the steps.

(6) This is an individual assignment.

(7) Your submission should consist of:

     (a) A report describing the solution to the problems. This report can be typewritten

or a scan of handwritten pages. This report must be in pdf format and must be

named report.pdf. The submission system will only accept the name report.pdf.

     (b) One or more computer programs if you use them to solve the problems numerically.

You should use zip to archive all the computer programs into one file with the name

supp.zip. The submission system will only accept this name. The report must refer

to the programs so that we know which program is used for which part.

(8) Submission can be made via the course website.

(9) You can submit as many times as you wish before the deadline. A later submission will

over-write the earlier one. We will only mark the last submission that you make.

(10) If you want to ask questions on the assignment, you can attend a consultation (see the

Timetable section of the course website for dates and times) or post your question on

the forum. Please note that if your forum post shows part of your solution or code, you

must mark that forum post private .

(11) Additional assignment conditions:

• Joint work is not permitted on this assignment.

     – This is an individual assignment. The work you submit must be entirely your

own work: submission of work even partly written by any other person is not

permitted.

     – Do not request help from anyone other than the teaching staff of COMP9344.

     – Do not post your assignment work or code to the course forum.

     – Assignment submissions are routinely examined both automatically and man

ually for work written by others.

Rationale: this assignment is designed to develop the individual skills needed to

solve problems. Using work/code written by, or taken from, other people will stop

you learning these skills. Other CSE courses focus on skills needed for working in

a team.

• The use of AI generative tools, such as ChatGPT, is not permitted on this assign

ment.

Rationale: this assignment is designed to develop your understanding of basic con

cepts. Using AI tools will stop you learning these fundamental concepts, which will

significantly impact your ability to complete future courses. Moreover, ChatGPT

has been found to give incorrect answers for advanced problems covered in this

course.

• Sharing, publishing, or distributing your assignment work is not permitted.

 

  – Do not provide or show your assignment work to any other person, other than

the teaching staff of COMP9334. For example, do not message your work to

friends.

  – Do not publish your assignment code via the Internet. For example, do not

place your assignment in a public GitHub repository.

Rationale: by publishing or sharing your work, you are facilitating other students

using your work. If other students find your assignment work and submit part

or all of it as their own work, you may become involved in an academic integrity

investigation.

• Sharing, publishing, or distributing your assignment work after the completion of

COMP9334 is not permitted.

  – For example, do not place your assignment in a public GitHub repository after

this offering of COMP9334 is over.

Rationale: COMP9334 may reuse assignment themes covering similar concepts and

content. If students in future terms find your assignment work and submit part

or all of it as their own work, you may become involved in an academic integrity

investigation.

 

Question 1 (5 marks)

Assuming that you are the administrator of an interactive computer system. The computer

system consists of a multi-core CPU and a disk. During an observation time of 1800 seconds,

you obtained the following measurements from the system:

 

This computer system is used by 16 interactive users and the thinking time per interactive

user is 45 seconds.

You consider the current throughput of the system is too low. You are considering a

proposal to upgrade the current CPU, which has 4 cores, to a new CPU with 6 cores and the

same processing speed per core as that of the current CPU.

For this question, you can assume that the total workload remains the same before and

after the upgrade. You can also assume that the workload is requests (note the plural) are

almost evenly distributed among the cores at the moment and the workload requests can still

be evenly distributed among the cores after the upgrade. As the system administrator, you

know that when the workload each request (note the singular) uses the CPU, it uses only one

core at a time, i.e., the workload a request does not use multiple cores concurrently.

Answer the following questions.

(a) Determine the current average service demand of a core.

(b) What will the average service demand per core be if the proposed CPU upgrade is

carried out?

     Hint: The service demand of a core depends on two factors: the number of visits to the

core and the service time needed per visit to the core. For the set up of this question,

one of these two factors remains the same after the upgrade, while the other factor will

change.

(c) What will the throughput bound of the computer system be if the proposed CPU

upgrade is carried out?

     Reminder: If you use a computer program to derive your numerical answers, you must

include your computer program in your submission. Do not forget to show us your steps to

obtain your answer.