A PROFIT MAXIMIZATION SCHEME WITH GUARANTEED QUALITY OF SERVICE IN CLOUD COMPUTING

A PROFIT MAXIMIZATION SCHEME WITH GUARANTEED
QUALITY OF SERVICE IN CLOUD COMPUTING
Abstract—As an effective and efficient way to provide computing resources and
services to customers on demand, cloud computing has become more and more
popular. From cloud service providers’ perspective, profit is one of the most
important considerations, and it is mainly determined by the configuration of a
cloud service platform under given market demand. However, a single long-term
renting scheme is usually adopted to configure a cloud platform, which cannot
guarantee the service quality but leads to serious resource waste. In this paper, a
double resource renting scheme is designed firstly in which short-term renting and
long-term renting are combined aiming at the existing issues. This double renting
scheme can effectively guarantee the quality of service of all requests and reduce
the resource waste greatly. Secondly, a service system is considered as an
M/M/m+D queuing model and the performance indicators that affect the profit of
our double renting scheme are analyzed, e.g., the average charge, the ratio of
requests that need temporary servers, and so forth. Thirdly, a profit maximization
problem is formulated for the double renting scheme and the optimized
configuration of a cloud platform is obtained by solving the profit maximization
problem. Finally, a series of calculations are conducted to compare the profit of our

proposed scheme with that of the single renting scheme. The results show that our
scheme can not only guarantee the service quality of all requests, but also obtain
more profit than the latter.
EXISTING SYSTEM:
In this section, we review recent works relevant to the profit of cloud service
providers. Profit of service providers is related with many factors such as the price,
the market demand, the system configuration, the customer satisfaction and so
forth. Service providers naturally wish to set a higher price to get a higher profit
margin; but doing so would decrease the customer satisfaction, which leads to a
risk of discouraging demand in the future. Hence, selecting a reasonable pricing
strategy is important for service providers. The pricing strategies are divided into
two categories, i.e., static pricing and dynamic pricing. Static pricing means that
the price of a service request is fixed and known in advance, and it does not change
with the conditions. With dynamic pricing a service provider delays the pricing
decision until after the customer demand is revealed, so that the service provider
can adjust prices accordingly. Static pricing is the dominant strategy which is
widely used in real world and in research. Ghamkhari et al. adopted a flat-rate
pricing strategy and set a fixed price for all requests, but Odlyzko argued that the

predominant flat-rate pricing encourages waste and is incompatible with service
differentiation. Another kind of static pricing strategies are usage-based pricing.
For example, the price of a service request is proportional to the service time and
task execution requirement (measured by the number of instructions to be
executed), respectively. Usage-based pricing reveals that one can use resources
more efficiently.
PROPOSED SYSTEM:
In this paper, we propose a novel renting scheme for service providers, which not
only can satisfy quality-of-service requirements, but also can obtain more profit.
Our contributions in this paper can be summarized as follows.
_ A novel double renting scheme is proposed for service providers. It combines
long-term renting with short-term renting, which can not only satisfy quality-of-
service requirements under the varying system workload, but also reduce the
resource waste greatly.
_ A multiserver system adopted in our paper is modeled as an M/M/m+D queuing
model and the performance indicators are analyzed such as the average service
charge, the ratio of requests that need shortterm servers, and so forth.

_ The optimal configuration problem of service providers for profit maximization
is formulated and two kinds of optimal solutions, i.e., the ideal solutions and the
actual solutions, are obtained respectively.
_ A series of comparisons are given to verify the performance of our scheme. The
results show that the proposed Double-Quality-Guaranteed (DQG) renting scheme
can achieve more profit than the compared Single-Quality-Unguaranteed (SQU)
renting scheme in the premise of guaranteeing the service quality completely. In
this paper, to overcome the shortcomings mentioned above, a double renting
scheme is designed to configure a cloud service platform, which can guarantee the
service quality of all requests and reduce the resource waste greatly. Moreover, a
profit maximization problem is formulated and solved to get the optimal
multiserver configuration which can product more profit than the optimal
configuration.
Module 1
A Cloud SystemModel
The cloud structure consists of three typical parties, i.e., infrastructure providers,
service providers and customers. This three-tier structure is used commonly in
existing literatures. In the three-tier structure, an infrastructure provider the basic

hardware and software facilities. A service provider rents resources from
infrastructure providers and prepares a set of services in the form of virtual
machine (VM). Infrastructure providers provide two kinds of resource renting
schemes, e.g., long-term renting and short-term renting. In general, the rental price
of long-term renting is much cheaper than that of short-term renting. A customer
submits a service request to a service provider which delivers services on demand.
The customer receives the desired result from the service provider with certain
service-level agreement, and pays for the service based on the amount of the
service and the service quality. Service providers pay infrastructure providers for
renting their physical resources, and charge customers for processing their service
requests, which generates cost and revenue, respectively. The profit is generated
from the gap between the revenue and the cost.
Module 2
A Multiserver Model
In this paper, we consider the cloud service platform as a multiserver system with a
service request queue. The schematic diagram of cloud computing. In an actual
cloud computing platform such as Amazon EC2, IBM blue cloud, and private
clouds, there are many work nodes managed by the cloud managers such as

Eucalyptus, OpenNebula, and Nimbus. The clouds provide resources for jobs in
the form of virtual machine (VM). In addition, the users submit their jobs to the
cloud in which a job queuing system such as SGE, PBS, or Condor is used. All
jobs are scheduled by the job scheduler and assigned to different VMs in a
centralized way. Hence, we can consider it as a service request queue. For
example, Condor is a specialized workload management system for
computeintensive jobs and it provides a job queueing mechanism, scheduling
policy, priority scheme, resource monitoring, and resource management. Users
submit their jobs to Condor, and Condor places them into a queue, chooses when
and where to run them based upon a polic. Hence, it is reasonable to abstract a
cloud service platform as a multiserver model with a service request queue, and the
model is widely adopted in existing literature. In the three-tier structure, a cloud
service provider serves customers’ service requests by using a multiserver system
which is rented from an infrastructure provider. Assume that the multiserver
system consists of m long-term rented identical servers, and it can be scaled up by
temporarily renting short-term servers from infrastructure providers. The servers
in the system have identical execution speed s (Unit: billion instructions per
second). In this paper, a multiserver system excluding the short-term servers is
modeled as an M/M/m queuing system as follows (see Fig. 3). There is a Poisson
stream of service requests with arrival rate λ, i.e., the interarrival times are

independent and identically distributed (i.i.d.) exponential random variables with
mean 1/λ. A multiserver system maintains a queue with infinite capacity. When the
incoming service requests cannot be processed immediately after they arrive, they
are firstly placed in the queue until they can be handled by any available server.
The first-come-first-served (FCFS) queuing discipline is adopted. The task
execution requirements (measured by the number of instructions) are independent
and identically distributed exponential random variables r with mean r (Unit:
billion instructions). Therefore, the execution times of tasks on the multiserver
system are also i.i.d. exponential random variables x = r/s with mean x = r/s (Unit
second). The average service rate of each server is calculated as μ = 1/x = s/r, and
the system utilization is defined as ρ = λ/mμ = λ/m _ r/s. Because the fixed
computing capacity of the service system is limited, some requests would wait for
a long time before they are served. According to the queuing theory, we have the
following theorem about the waiting time in an M/M/m queuing system.
Module 3
The ProposedScheme
In this section, we first propose the Double-Quality- Guaranteed (DQG) resource
renting scheme which combines long-term renting with short-term renting. The

main computing capacity is provided by the long-term rented servers due to their
low price. The short-term rented servers provide the extra capacity in peak period.
The proposed DQG scheme adopts the traditional FCFS queueing discipline. For
each service request entering the system, the system records its waiting time. The
requests are assigned and executed on the long-term rented servers in the order of
arrival times. Once the waiting time of a request reaches D, a temporary server is
rented from infrastructure providers to process the request. We consider the novel
service model as an M/M/m+D queuing model. The M/M/m+D model is a special
M/M/m queuing model with impatient customers. In an M/M/m+D model, the
requests are impatient and they have a maximal tolerable waiting time. If the
waiting time exceeds the tolerable waiting time, they lose patience and leave the
system. In our scheme, the impatient requests do not leave the system but are
assigned to temporary rented servers. Since the requests with waiting time D are all
assigned to temporary servers, it is apparent that all service requests can guarantee
their deadline and are charged based on the workload according to the SLA.
Hence, the revenue of the service provider increases. However, the cost increases
as well due to the temporarily rented servers. Moreover, the amount of cost spent
in renting temporary servers is determined by the computing capacity of the long-
term rented multiserver system. Since the revenue has been maximized using our
scheme, minimizing the cost is the key issue for profit maximization. Next, the

tradeoff between the longterm rental cost and the short-term rental cost is
considered, and an optimal problem is formulated in the following to get the
optimal long-term configuration such that the profit is maximized.
CONCLUSIONS
In order to guarantee the quality of service requests and maximize the profit of
service providers, this paper has proposed a novel Double-Quality-Guaranteed
(DQG) renting scheme for service providers. This scheme combines short-term
renting with long-term renting, which can reduce the resource waste greatly and
adapt to the dynamical demand of computing capacity. An M/M/m+D queueing
model is build for our multiserver system with varying system size. And then, an
optimal configuration problem of profit maximization is formulated in which many
factors are taken into considerations, such as the market demand, the workload of
requests, the server-level agreement, the rental cost of servers, the cost of energy
consumption, and so forth. The optimal solutions are solved for two different
situations, which are the ideal optimal solutions and the actual optimal solutions. In
addition, a series of calculations are conducted to compare the profit obtained by
the DQG renting scheme with the Single-Quality-Unguaranteed (SQU) renting
scheme. The results show that our scheme outperforms the SQU scheme in terms

of both of service quality and profit. In this paper, we only consider the profit
maximization problem in a homogeneous cloud environment, because the analysis
of a heterogenous environment is much more complicated than that of a
homogenous environment. However, we will extend our study to a heterogenous
environment in the future.
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A PROFIT MAXIMIZATION SCHEME WITH GUARANTEED QUALITY OF SERVICE IN CLOUD COMPUTING

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A PROFIT MAXIMIZATION SCHEME WITH GUARANTEED QUALITY OF SERVICE IN CLOUD COMPUTING