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1. [20 points, 1 each] true or false, circle t or f.

a. A binary semaphore takes on numerical values 0 and 1 only.

b. An atomic operation is a machine instruction or a sequence of instructions

that must be executed to completion without interruption.

c. Deadlock is a situation in which two or more processes (or threads) are waiting for an event that will occur in the future

d. Starvation is a situation in which a process is denied access to a resource

because of the competitive activity of other, possibly unrelated, processes.

e. While a process is blocked on a semaphore's queue, it is engaged in busy waiting.

f. Circular waiting is a necessary condition for deadlock, but not a sufficient

condition a condition for the deadlock to occur.

g. Mutual exclusion can be enforced with a general semaphore whose initial value is greater than 1

h. External fragmentation can occur in a paged virtual memory system.

i. External fragmentation can be prevented (almost completely) by frequent use of compaction, but the cost would be too high for most systems.

j. A page frame is a portion of main memory.

k. Once a virtual memory page is locked into main memory, it cannot be written to the disk.

l. Pages that are shared between two or more processes can never be swapped out to the disk.

m. The allocated portions of memory using a buddy system are all the same size.

n. Demand paging requires the programmer to take specific action to force the

operating system to load a particular virtual memory page.

o. Prepaging is one possibility for the fetch policy in a virtual memory system.

p. The resident set of a process can be changed in response to actions by other processes.

q. The working set of a process can be changed in response to actions by other processes.

r. The translation lookaside buffer is a software data structure that supports he virtual memory address translation operation.

s. In a symmetric multiprocessor, threads can always be run on any processor.

t. Thrashing will never be a problem if the system has 1 GB of real memory.

2. [20 points, 5 each] short answers and simple diagrams.

(a) Define the resident set of a process.

(b) Define the working set of a process.

(c) What problems could occur if virtual memory pages are always allocated in groups of four?

(d) What information is used by the Least Recently Used page replacement policy, and how does this compare to the information used by the various Clock algorithms?

3. [20 points, 5 each] short answers and simple diagrams.

(a) In terms of memory allocation, what is a reference counter? Why is it needed?

(b) Explain why, or why not, internal fragmentation can be a problem when using the best fit algorithm for memory allocation.

(c) One of the options in a mainframe OS is to limit the number of jobs (processes) currently in the system. What are some of the benefits of this capability?

(d) In what circumstances of virtual memory is the placement policy an important issue?

4. [20 points, 5 each] short answers.

(a) What are four general characteristics of processor scheduling policies?

(b) Define Turnaround Time and Normalized Turnaround Time. Why are these useful for measuring the performance of a scheduling algorithm?

(c) What would be the effect of a large number of page faults by a process on that process's page allocation on a nonpreemptive operating system?

(d) What are four actions or decisions that a preemptive virtual memory operating system would make at the end of a time quantum (in response to a timer interrupt)?

5. [20 points]

This function is proposed for use in an operating system, with the definitions of

Process, Process_Set and other functions given elsewhere.

Process next_process(Process_Set available_processes) {

Process_Set A = highest_valuation(available_processes); /* priority ranking */

Process_Set B = earliest(A); /* actual arrival time */

Process c = random_selection(B); /* tie-breaker */

return c; /* run this process next */


(a) [5] Explain why this function could lead to processor starvation among the available processes.

(b) [5] Suppose one of the criteria used by the highest_valuation function is the process's fraction of virtual memory pages currently in main memory. Explain why this is not a good idea.

(c) [10] Define a version of the highest_valuation function (in the same style, but with some more descriptive comments) for the Shortest Process Next scheduling policy. Describe the data requirements and how this data is obtained.

Questions & Answers

microeconomics study part of the economy but macroeconomic study the whole economy
Olokun Reply
studying the whole economy, solving the problem of the economy and building up the economy
micro means small while macro means large
standard of living is the footsteps of an economy because it plays important role for country to have crucial view about their budget ,import and export
it will be differ because economic agent will only take their views on some part of household
can opportunity cost be zero
OBED Reply
how many types of transportation do we have
yes. when a customer's purchasing power is high, he may have d ability to purchase all he needs, dt makes opportunity cost zero
please can give more explanation on this question
what are the factors production
Labour capital entrepreneurs
Land,capital, labour,and the entrepreneur
I will like to know use of calculus in economics
do they use it in economics?
I want to know if I should take calculus or statistics and probability my senior year of highschool
yes for example in monopolistic competitive market..... TR=TC* & THIS CALCULATED BY CHANGING( DERIVATIVE LAW) MR =MC ** WILL BE THE FORMULA THAT USE.
please in which topic in economic is the question coming from.
from PCF in economics
why is unitary proportional to responsiveness
Etim Reply
any tip for igcse economics exam?pls
Stacey Reply
What is a market
Divine Reply
what are the variables that affect demand
what are the variables that affect demand
what are the variables that affect demand
what are the variables that affect demand
what are the variables that affect demand
price of the related goods 2 price of the given commodity 3 income of the consumer 4 taste and preference 5 expectation in the future price
pls the taste and preference
explain briefly
a consumer taste and preference commodity changes for a time the man becomes
sorry sorry
is when the price of a commodity becomes high and can't afford example Samsung instead of iPhone
consumers who have high intense for goods will purchase the goods even if the price of that commodity increases because he or she preferred that commodity.people will be prefer iphone as its price increase
as usual bad taste of preference is when a consumer regrets from one commodity to another in terms of the price
thanks alot
you're welcome
#Preference; #Income #Test
#price Of Commodity #Income #Taste #Preference
#Market is The Place Where Buyers And Sellers Are Exchanging Their Goods And service. #
difference between macro and micro economics
Microeconomic Study about individual consumers market But Macroeconomis Study General economic Process Such As #Aggregate Demand #Aggregate Supples #GDp= #GNp
nice so can u run down a brife discussion on GDP
pls can someone differentiate between the perfectly elastic, perfectly inelastic and unitary
yhar Reply
and then again pls what are the types of elasticity, the methods of calculating it thank u
Perfectly inelastic is when the coefficient is equal to zero Unitary is when the coefficient is equal to one But am not sure if we have perfectly inelastic
I'm kind off confuse abt the PED, IED and co are they the types of elasticity we've
Yh the types are price elasticity cross and income elasticity of demand
do we've specific formulaes to calculate for each of them
yes. PED. changes in quantity demanded divided by changes in price
so pls what's the general name given to unitary, elastic n inelastic ? are the names given to the final result after doing the calculations?
P2-P1÷P1×100or Q2-Q1×Q1×100 PED
They are elasticity coefficient
@John I don't get u well pls
P2-P1÷P1×100or Q2-Q1×Q1×100 PED @john pls tis is what m talking abt
Yh is the formula for PED
Pls are you having a for PED
thank u very
what is economics
economics is a science which studies human behaviour as a relationship between ends and scarce means which have alternative use
is a science which study human behavior as a relationship between ends and scarce means which have alternative uses
yes this is because economic provide a body of knowledge on human economic principles under theories and these theories can be verified with real world data using science method in other words it was scientific method in arriving at solution identification of problem or basic data collection among
unitary ElasticWhen Elasticty =1 Perfectily Elastic When 0<1 inelastic when 0>
Pls is anyone having the NovDec questions?
John Reply
what is micro economics
Rakesh Reply
What is PPF
Production Possibility Frontier
It refers to a curve or graph which shows the possible contributions of maximum alternative of commodity that can be produced in an economy
Thanks John talkx of defination pls
I don't get you
guys Any One With Novdec Questions 2019?
Diana Reply
what did Adam Smith introduce?
Sunday Reply
what is supply
Awunyo Reply
supply relationship shows that the higher the price, the higher the quantity supplied. 
what are the dissadvantages of large scale production
Atanga Reply
depreciate of quality taste
Some of the Disadvantages are:- 1. Production not according to individual Tastes 2. Monopoly 3. Not Flexible 4. Over-Production 5. Heavy loss and Dislocation 6. Decline of Cottage and Small Scale Industries 7. Adverse Effect on Labourers 8. Unequal Distribution of Wealth
And what can be the advantages too
1.adequate satisfaction 2.reduce importation
Reduce importation how pls
the country will have enough products.this will reduce the level of government expenditure on imported goods especially
Some of Advantage 1. Division of Labour 2. More Production 3. Use of machines 4. Low Cost of Production 5. Standard Goods 6. Advertisements and Salesmanship
Some of its disadvantages are : (i) Less Supervision (ii) Individual tastes ignored (iii) Absence of Personal Element (iv) Possibility of depression (v) Dependence on Foreign Markets (vi) International complications and war (vii) Cut-throat Competition (viii) Less Adaptability
what are the types of trade cycle
Kenny Reply
in a comparison of the stages of meiosis to the stage of mitosis, which stages are unique to meiosis and which stages have the same event in botg meiosis and mitosis
Leah Reply
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Source:  OpenStax, Operating systems. OpenStax CNX. Aug 13, 2009 Download for free at http://cnx.org/content/col10785/1.2
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