Imprecise computation model is used in dynamic scheduling algorithm having heuristic function to
schedule task sets. A task is characterized by ready time, worst case computation time, deadline and resource
requirements. A task failing to meet its deadline and resource requirements on time is split into mandatory part
and optional part. These sub-tasks of a task can execute concurrently on multiple cores, thus achieving
parallelization provided by the multi-core system. Mandatory part produces acceptable results while optional
part refines the result further. To study the effectiveness of proposed scheduling algorithm, extensive simulation
studies have been carried out. Performance of proposed scheduling algorithm is compared with myopic and
improved myopic scheduling algorithm. The simulation studies shows that schedulability of task split myopic
algorithm is always higher than myopic and improved myopic algorithm.
Implementation and evaluation of novel scheduler of UC/OS (RTOS)Editor Jacotech
At present, there are more than a billion embedded applications either real time or non-real time. Among them, many appli cations require Prioritized queue of periodic tasks. UC/OS, one of the most widely Used real-time kernels in industry, has preemptive scheduler and doesn't Support two tasks at same priority level. This work proposes a modification in scheduler of UC/OS (RTOS) to make it more exible in handling a periodic and periodic task. The proposed scheduler allows assigning same priority to more than one task. Tasks with same priority are in queue, where their position is decided on first come (created) first Served basis. Time-slicing is used for scheduling tasks in same queue. Emendations in the task management and scheduler have been explained in detailed. Evaluation, to observe the effect of modified scheduling on Overhead of system calls is done on an evaluation board.
(Paper) Task scheduling algorithm for multicore processor system for minimiz...Naoki Shibata
Shohei Gotoda, Naoki Shibata and Minoru Ito : "Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault," Proceedings of IEEE International Symposium on Cluster Computing and the Grid (CCGrid 2012), pp.260-267, DOI:10.1109/CCGrid.2012.23, May 15, 2012.
In this paper, we propose a task scheduling al-gorithm for a multicore processor system which reduces the
recovery time in case of a single fail-stop failure of a multicore
processor. Many of the recently developed processors have
multiple cores on a single die, so that one failure of a computing
node results in failure of many processors. In the case of a failure
of a multicore processor, all tasks which have been executed
on the failed multicore processor have to be recovered at once.
The proposed algorithm is based on an existing checkpointing
technique, and we assume that the state is saved when nodes
send results to the next node. If a series of computations that
depends on former results is executed on a single die, we need
to execute all parts of the series of computations again in
the case of failure of the processor. The proposed scheduling
algorithm tries not to concentrate tasks to processors on a die.
We designed our algorithm as a parallel algorithm that achieves
O(n) speedup where n is the number of processors. We evaluated
our method using simulations and experiments with four PCs.
We compared our method with existing scheduling method, and
in the simulation, the execution time including recovery time in
the case of a node failure is reduced by up to 50% while the
overhead in the case of no failure was a few percent in typical
scenarios.
In the era of big data, even though we have large infrastructure, storage data varies in size,
formats, variety, volume and several platforms such as hadoop, cloud since we have problem associated
with an application how to process the data which is varying in size and format. Data varying in
application and resources available during run time is called dynamic workflow. Using large
infrastructure and huge amount of resources for the analysis of data is time consuming and waste of
resources, it’s better to use scheduling algorithm to analyse the given data set, for efficient execution of
data set without time consuming and evaluate which scheduling algorithm is best and suitable for the
given data set. We evaluate with different data set understand which is the most suitable algorithm for
analysis of data being efficient execution of data set and store the data after analysis
Implementation and evaluation of novel scheduler of UC/OS (RTOS)Editor Jacotech
At present, there are more than a billion embedded applications either real time or non-real time. Among them, many appli cations require Prioritized queue of periodic tasks. UC/OS, one of the most widely Used real-time kernels in industry, has preemptive scheduler and doesn't Support two tasks at same priority level. This work proposes a modification in scheduler of UC/OS (RTOS) to make it more exible in handling a periodic and periodic task. The proposed scheduler allows assigning same priority to more than one task. Tasks with same priority are in queue, where their position is decided on first come (created) first Served basis. Time-slicing is used for scheduling tasks in same queue. Emendations in the task management and scheduler have been explained in detailed. Evaluation, to observe the effect of modified scheduling on Overhead of system calls is done on an evaluation board.
(Paper) Task scheduling algorithm for multicore processor system for minimiz...Naoki Shibata
Shohei Gotoda, Naoki Shibata and Minoru Ito : "Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault," Proceedings of IEEE International Symposium on Cluster Computing and the Grid (CCGrid 2012), pp.260-267, DOI:10.1109/CCGrid.2012.23, May 15, 2012.
In this paper, we propose a task scheduling al-gorithm for a multicore processor system which reduces the
recovery time in case of a single fail-stop failure of a multicore
processor. Many of the recently developed processors have
multiple cores on a single die, so that one failure of a computing
node results in failure of many processors. In the case of a failure
of a multicore processor, all tasks which have been executed
on the failed multicore processor have to be recovered at once.
The proposed algorithm is based on an existing checkpointing
technique, and we assume that the state is saved when nodes
send results to the next node. If a series of computations that
depends on former results is executed on a single die, we need
to execute all parts of the series of computations again in
the case of failure of the processor. The proposed scheduling
algorithm tries not to concentrate tasks to processors on a die.
We designed our algorithm as a parallel algorithm that achieves
O(n) speedup where n is the number of processors. We evaluated
our method using simulations and experiments with four PCs.
We compared our method with existing scheduling method, and
in the simulation, the execution time including recovery time in
the case of a node failure is reduced by up to 50% while the
overhead in the case of no failure was a few percent in typical
scenarios.
In the era of big data, even though we have large infrastructure, storage data varies in size,
formats, variety, volume and several platforms such as hadoop, cloud since we have problem associated
with an application how to process the data which is varying in size and format. Data varying in
application and resources available during run time is called dynamic workflow. Using large
infrastructure and huge amount of resources for the analysis of data is time consuming and waste of
resources, it’s better to use scheduling algorithm to analyse the given data set, for efficient execution of
data set without time consuming and evaluate which scheduling algorithm is best and suitable for the
given data set. We evaluate with different data set understand which is the most suitable algorithm for
analysis of data being efficient execution of data set and store the data after analysis
Job Resource Ratio Based Priority Driven Scheduling in Cloud Computingijsrd.com
Cloud Computing is an emerging technology in the area of parallel and distributed computing. Clouds consist of a collection of virtualized resources, which include both computational and storage facilities that can be provisioned on demand, depending on the users' needs. Job scheduling is one of the major activities performed in all the computing environments. Cloud computing is one the upcoming latest technology which is developing drastically. To efficiently increase the working of cloud computing environments, job scheduling is one the tasks performed in order to gain maximum profit. In this paper we proposed a new scheduling algorithm based on priority and that priority is based on ratio of job and resource. To calculate priority of job we use analytical hierarchy process. In this paper we also compare result with other algorithm like First come first serve and round robin algorithms.
Task scheduling is an important aspect to improve the utilization of resources in the Cloud Computing. This paper proposes a Divide and Conquer based approach for heterogeneous earliest finish time algorithm. The proposed system works in two phases. In the first phase it assigns the ranks to the incoming tasks with respect to size of it. In the second phase, we properly assign and manage the task to the virtual machine with the consideration of ideal time of respective virtual machine. This helps to get more effective resource utilization in Cloud Computing. The experimental results using Cybershake Scientific Workflow shows that the proposed Divide and Conquer HEFT performs better than HEFT in terms of task's finish time and response time. The result obtained by experimentally demonstrate that the proposed DCHEFT performance superiorly.
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Optimizing Linux Kernel for Real-time Performance On Multi-Core ArchitectureCSCJournals
Linux kernel developed and distributed in open source doesn’t support for Hard Real-time scheduling. The open source Linux kernels are designed in time sharing manner to obtain maximum throughput. With this, Linux Operating System is considered to be an OS, which is not supporting Real-Time Applications, natively it has some features, already included in the mainstream to provide real-time support. There are certain modified Linux kernels like RTLinux, Symbian OS, Nucleus OS, Lynx OS and Fusion RTOS [1] which are explicitly designed for hard Real-Time support [2]. These specially designed Real-Time Linux kernels is mostly targeted for special hardware’s like embedded systems, robots, safety critical etc. ,very few kernels for general purpose. Most of these kernels are be available as proprietary or closed, excluding a very few and not suitable for all hardware architecture’s.
Now a days Real-Time Performance has become universal requirement for computer games, multimedia systems, household monitoring and controlling appliances. So the general purpose Linux kernel needs to be optimized, to achieve Real-time performance to meet the user expectations. This paper tries to extract real-time performance from general kernel and suggest some techniques to optimize Linux kernel to meet real-time deadlines.
Comparative Analysis of Various Grid Based Scheduling Algorithmsiosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
SWARM INTELLIGENCE SCHEDULING OF SOFT REAL-TIME TASKS IN HETEROGENEOUS MULTIP...ecij
In this paper, a hybrid swarm intelligence algorithm (named VNABCSA) is presented for the scheduling of non-preemptive soft real-time tasks in heterogeneous multiprocessor platforms. The method is based on a combination of artificial bee colony and simulated annealing algorithms. The multi-objective function of the VNABCSA algorithm is defined to minimize the total tardiness of all tasks, total number of utilized processors, total completion time, total waiting time for all tasks, and total waiting time for all processors. We introduce a hybrid variable neighborhood search strategy to improve the convergence speed of the algorithm. Simulation results demonstrate the efficiency of the proposed methodology as compared with the
existing scheduling algorithms.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
(Slides) Task scheduling algorithm for multicore processor system for minimiz...Naoki Shibata
Shohei Gotoda, Naoki Shibata and Minoru Ito : "Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault," Proceedings of IEEE International Symposium on Cluster Computing and the Grid (CCGrid 2012), pp.260-267, DOI:10.1109/CCGrid.2012.23, May 15, 2012.
In this paper, we propose a task scheduling al-gorithm for a multicore processor system which reduces the
recovery time in case of a single fail-stop failure of a multicore
processor. Many of the recently developed processors have
multiple cores on a single die, so that one failure of a computing
node results in failure of many processors. In the case of a failure
of a multicore processor, all tasks which have been executed
on the failed multicore processor have to be recovered at once.
The proposed algorithm is based on an existing checkpointing
technique, and we assume that the state is saved when nodes
send results to the next node. If a series of computations that
depends on former results is executed on a single die, we need
to execute all parts of the series of computations again in
the case of failure of the processor. The proposed scheduling
algorithm tries not to concentrate tasks to processors on a die.
We designed our algorithm as a parallel algorithm that achieves
O(n) speedup where n is the number of processors. We evaluated
our method using simulations and experiments with four PCs.
We compared our method with existing scheduling method, and
in the simulation, the execution time including recovery time in
the case of a node failure is reduced by up to 50% while the
overhead in the case of no failure was a few percent in typical
scenarios.
Optimized Assignment of Independent Task for Improving Resources Performance ...ijgca
Grid computing has emerged from category of distributed and parallel computing where the
heterogeneous resources from different network are used simultaneously to solve a particular problem that
need huge amount of resources. Potential of Grid computing depends on my issues such as security of
resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling
is one of the core steps to efficiently exploit the capabilities of heterogeneous distributed computing
resources and is an NP-complete problem. To achieve the promising potential of grid computing, an
effective and efficient job scheduling algorithm is proposed, which will optimized two important criteria to
improve the performance of resources i.e. makespan time & resource utilization. With this, we have
classified various tasks scheduling heuristic in grid on the basis of their characteristics.
Optimized Assignment of Independent Task for Improving Resources Performance ...Ricardo014
Grid computing has emerged from category of distributed and parallel computing where the heterogeneous resources from different network are used simultaneously to solve a particular problem that need huge amount of
resources. Potential of Grid computing depends on my issues such as security of resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling is one of the core steps to
efficiently exploit the capabilities of heterogeneous distributed computing resources and is an NP-complete problem. To achieve the promising potential of grid computing, an effective and efficient job scheduling algorithm is
proposed, which will optimized two important criteria to improve the performance of resources i.e. makespan time & resource utilization. With this, we have classified various tasks scheduling heuristic in grid on the basis of
their characteristics.
Optimized Assignment of Independent Task for Improving Resources Performance ...ijgca
Grid computing has emerged from category of distributed and parallel computing where the heterogeneous resources from different network are used simultaneously to solve a particular problem that need huge amount of resources. Potential of Grid computing depends on my issues such as security of resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling is one of the core steps to efficiently exploit the capabilities of heterogeneous distributed computing resources and is an NP-complete problem. To achieve the promising potential of grid computing, an effective and efficient job scheduling algorithm is proposed, which will optimized two important criteria to improve the performance of resources i.e. makespan time & resource utilization. With this, we have classified various tasks scheduling heuristic in grid on the basis of their characteristics.
SCHEDULING DIFFERENT CUSTOMER ACTIVITIES WITH SENSING DEVICEijait
Most periodic tasks are assigned to processors using partition scheduling policy after checking feasibility conditions. A new approach is proposed for scheduling different activities with one periodic task within the system. In this paper, control strategies are identified for allocating different types of tasks (activities) to
individual computing elements like Smartphone or microphones. In our simulation model, each periodic task generates an aperiodic tasks are taken into consideration. Different sets of periodic tasks and aperiodic tasks are scheduled together. This new approach proves that when all different activities are
scheduled with one periodic tasks leads to better performance.
Job Resource Ratio Based Priority Driven Scheduling in Cloud Computingijsrd.com
Cloud Computing is an emerging technology in the area of parallel and distributed computing. Clouds consist of a collection of virtualized resources, which include both computational and storage facilities that can be provisioned on demand, depending on the users' needs. Job scheduling is one of the major activities performed in all the computing environments. Cloud computing is one the upcoming latest technology which is developing drastically. To efficiently increase the working of cloud computing environments, job scheduling is one the tasks performed in order to gain maximum profit. In this paper we proposed a new scheduling algorithm based on priority and that priority is based on ratio of job and resource. To calculate priority of job we use analytical hierarchy process. In this paper we also compare result with other algorithm like First come first serve and round robin algorithms.
Task scheduling is an important aspect to improve the utilization of resources in the Cloud Computing. This paper proposes a Divide and Conquer based approach for heterogeneous earliest finish time algorithm. The proposed system works in two phases. In the first phase it assigns the ranks to the incoming tasks with respect to size of it. In the second phase, we properly assign and manage the task to the virtual machine with the consideration of ideal time of respective virtual machine. This helps to get more effective resource utilization in Cloud Computing. The experimental results using Cybershake Scientific Workflow shows that the proposed Divide and Conquer HEFT performs better than HEFT in terms of task's finish time and response time. The result obtained by experimentally demonstrate that the proposed DCHEFT performance superiorly.
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Optimizing Linux Kernel for Real-time Performance On Multi-Core ArchitectureCSCJournals
Linux kernel developed and distributed in open source doesn’t support for Hard Real-time scheduling. The open source Linux kernels are designed in time sharing manner to obtain maximum throughput. With this, Linux Operating System is considered to be an OS, which is not supporting Real-Time Applications, natively it has some features, already included in the mainstream to provide real-time support. There are certain modified Linux kernels like RTLinux, Symbian OS, Nucleus OS, Lynx OS and Fusion RTOS [1] which are explicitly designed for hard Real-Time support [2]. These specially designed Real-Time Linux kernels is mostly targeted for special hardware’s like embedded systems, robots, safety critical etc. ,very few kernels for general purpose. Most of these kernels are be available as proprietary or closed, excluding a very few and not suitable for all hardware architecture’s.
Now a days Real-Time Performance has become universal requirement for computer games, multimedia systems, household monitoring and controlling appliances. So the general purpose Linux kernel needs to be optimized, to achieve Real-time performance to meet the user expectations. This paper tries to extract real-time performance from general kernel and suggest some techniques to optimize Linux kernel to meet real-time deadlines.
Comparative Analysis of Various Grid Based Scheduling Algorithmsiosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
SWARM INTELLIGENCE SCHEDULING OF SOFT REAL-TIME TASKS IN HETEROGENEOUS MULTIP...ecij
In this paper, a hybrid swarm intelligence algorithm (named VNABCSA) is presented for the scheduling of non-preemptive soft real-time tasks in heterogeneous multiprocessor platforms. The method is based on a combination of artificial bee colony and simulated annealing algorithms. The multi-objective function of the VNABCSA algorithm is defined to minimize the total tardiness of all tasks, total number of utilized processors, total completion time, total waiting time for all tasks, and total waiting time for all processors. We introduce a hybrid variable neighborhood search strategy to improve the convergence speed of the algorithm. Simulation results demonstrate the efficiency of the proposed methodology as compared with the
existing scheduling algorithms.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
(Slides) Task scheduling algorithm for multicore processor system for minimiz...Naoki Shibata
Shohei Gotoda, Naoki Shibata and Minoru Ito : "Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault," Proceedings of IEEE International Symposium on Cluster Computing and the Grid (CCGrid 2012), pp.260-267, DOI:10.1109/CCGrid.2012.23, May 15, 2012.
In this paper, we propose a task scheduling al-gorithm for a multicore processor system which reduces the
recovery time in case of a single fail-stop failure of a multicore
processor. Many of the recently developed processors have
multiple cores on a single die, so that one failure of a computing
node results in failure of many processors. In the case of a failure
of a multicore processor, all tasks which have been executed
on the failed multicore processor have to be recovered at once.
The proposed algorithm is based on an existing checkpointing
technique, and we assume that the state is saved when nodes
send results to the next node. If a series of computations that
depends on former results is executed on a single die, we need
to execute all parts of the series of computations again in
the case of failure of the processor. The proposed scheduling
algorithm tries not to concentrate tasks to processors on a die.
We designed our algorithm as a parallel algorithm that achieves
O(n) speedup where n is the number of processors. We evaluated
our method using simulations and experiments with four PCs.
We compared our method with existing scheduling method, and
in the simulation, the execution time including recovery time in
the case of a node failure is reduced by up to 50% while the
overhead in the case of no failure was a few percent in typical
scenarios.
Optimized Assignment of Independent Task for Improving Resources Performance ...ijgca
Grid computing has emerged from category of distributed and parallel computing where the
heterogeneous resources from different network are used simultaneously to solve a particular problem that
need huge amount of resources. Potential of Grid computing depends on my issues such as security of
resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling
is one of the core steps to efficiently exploit the capabilities of heterogeneous distributed computing
resources and is an NP-complete problem. To achieve the promising potential of grid computing, an
effective and efficient job scheduling algorithm is proposed, which will optimized two important criteria to
improve the performance of resources i.e. makespan time & resource utilization. With this, we have
classified various tasks scheduling heuristic in grid on the basis of their characteristics.
Optimized Assignment of Independent Task for Improving Resources Performance ...Ricardo014
Grid computing has emerged from category of distributed and parallel computing where the heterogeneous resources from different network are used simultaneously to solve a particular problem that need huge amount of
resources. Potential of Grid computing depends on my issues such as security of resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling is one of the core steps to
efficiently exploit the capabilities of heterogeneous distributed computing resources and is an NP-complete problem. To achieve the promising potential of grid computing, an effective and efficient job scheduling algorithm is
proposed, which will optimized two important criteria to improve the performance of resources i.e. makespan time & resource utilization. With this, we have classified various tasks scheduling heuristic in grid on the basis of
their characteristics.
Optimized Assignment of Independent Task for Improving Resources Performance ...ijgca
Grid computing has emerged from category of distributed and parallel computing where the heterogeneous resources from different network are used simultaneously to solve a particular problem that need huge amount of resources. Potential of Grid computing depends on my issues such as security of resources, heterogeneity of resources, fault tolerance & resource discovery and job scheduling. Scheduling is one of the core steps to efficiently exploit the capabilities of heterogeneous distributed computing resources and is an NP-complete problem. To achieve the promising potential of grid computing, an effective and efficient job scheduling algorithm is proposed, which will optimized two important criteria to improve the performance of resources i.e. makespan time & resource utilization. With this, we have classified various tasks scheduling heuristic in grid on the basis of their characteristics.
SCHEDULING DIFFERENT CUSTOMER ACTIVITIES WITH SENSING DEVICEijait
Most periodic tasks are assigned to processors using partition scheduling policy after checking feasibility conditions. A new approach is proposed for scheduling different activities with one periodic task within the system. In this paper, control strategies are identified for allocating different types of tasks (activities) to
individual computing elements like Smartphone or microphones. In our simulation model, each periodic task generates an aperiodic tasks are taken into consideration. Different sets of periodic tasks and aperiodic tasks are scheduled together. This new approach proves that when all different activities are
scheduled with one periodic tasks leads to better performance.
Reinforcement learning based multi core scheduling (RLBMCS) for real time sys...IJECEIAES
Embedded systems with multi core processors are increasingly popular because of the diversity of applications that can be run on it. In this work, a reinforcement learning based scheduling method is proposed to handle the real time tasks in multi core systems with effective CPU usage and lower response time. The priority of the tasks is varied dynamically to ensure fairness with reinforcement learning based priority assignment and Multi Core MultiLevel Feedback queue (MCMLFQ) to manage the task execution in multi core system
Multiprocessor scheduling of dependent tasks to minimize makespan and reliabi...ijfcstjournal
Algorithms developed for scheduling applications on heterogeneous multiprocessor system focus on a
single objective such as execution time, cost or total data transmission time. However, if more than one
objective (e.g. execution cost and time, which may be in conflict) are considered, then the problem becomes
more challenging. This project is proposed to develop a multiobjective scheduling algorithm using
Evolutionary techniques for scheduling a set of dependent tasks on available resources in a multiprocessor
environment which will minimize the makespan and reliability cost. A Non-dominated sorting Genetic
Algorithm-II procedure has been developed to get the pareto- optimal solutions. NSGA-II is a Elitist
Evolutionary algorithm, and it takes the initial parental solution without any changes, in all iteration to
eliminate the problem of loss of some pareto-optimal solutions.NSGA-II uses crowding distance concept to
create a diversity of the solutions.
DYNAMIC TASK PARTITIONING MODEL IN PARALLEL COMPUTINGcscpconf
Parallel computing systems compose task partitioning strategies in a true multiprocessing
manner. Such systems share the algorithm and processing unit as computing resources which
leads to highly inter process communications capabilities. The main part of the proposed
algorithm is resource management unit which performs task partitioning and co-scheduling .In
this paper, we present a technique for integrated task partitioning and co-scheduling on the
privately owned network. We focus on real-time and non preemptive systems. A large variety of
experiments have been conducted on the proposed algorithm using synthetic and real tasks.
Goal of computation model is to provide a realistic representation of the costs of programming
The results show the benefit of the task partitioning. The main characteristics of our method are
optimal scheduling and strong link between partitioning, scheduling and communication. Some
important models for task partitioning are also discussed in the paper. We target the algorithm
for task partitioning which improve the inter process communication between the tasks and use
the recourses of the system in the efficient manner. The proposed algorithm contributes the
inter-process communication cost minimization amongst the executing processes.
Bragged Regression Tree Algorithm for Dynamic Distribution and Scheduling of ...Editor IJCATR
In the past few years, Grid computing came up as next generation computing platform which is a combination of
heterogeneous computing resources combined by a network across dynamic and geographically separated organizations. So, it
provides the perfect computing environment to solve large-scale computational demands. As the Grid computing demands are still
increasing from day to day due to rise in large number of complex jobs worldwide. So, the jobs may take much longer time to
complete due to poor distribution of batches or groups of jobs to inappropriate CPU’s. Therefore there is need to develop an efficient
dynamic job scheduling algorithm that would assign jobs to appropriate CPU’s dynamically. The main problem which dealt in the
paper is, how to distribute the jobs when the payload, importance, urgency, flow time etc. dynamically keeps on changing as the grid
expands or is flooded with number of job requests from different machines within the grid.
In this paper, we present a scheduling strategy which takes the advantage of decision tree algorithm to take dynamic decision
based on the current scenarios and which automatically incorporates factor analysis for considering the distribution of jobs.
Temporally Extended Actions For Reinforcement Learning Based Schedulers IJSCAI Journal
Temporally extended actions have been proved to enhance the performance of reinforcement learning
agents. The broader framework of ‘Options’ gives us a flexible way of representing such extended course of
action in Markov decision processes. In this work we try to adapt options framework to model an operating
system scheduler, which is expected not to allow processor stay idle if there is any process ready or waiting
for its execution. A process is allowed to utilize CPU resources for a fixed quantum of time (timeslice) and
subsequent context switch leads to considerable overhead. In this work we try to utilize the historical
performances of a scheduler and try to reduce the number of redundant context switches. We propose a
machine-learning module, based on temporally extended reinforcement-learning agent, to predict a better
performing timeslice. We measure the importance of states, in option framework, by evaluating the impact
of their absence and propose an algorithm to identify such checkpoint states. We present empirical
evaluation of our approach in a maze-world navigation and their implications on "adaptive timeslice
parameter" show efficient throughput time.
TEMPORALLY EXTENDED ACTIONS FOR REINFORCEMENT LEARNING BASED SCHEDULERSijscai
Temporally extended actions have been proved to enhance the performance of reinforcement learning agents. The broader framework of ‘Options’ gives us a flexible way of representing such extended course of action in Markov decision processes. In this work we try to adapt options framework to model an operating system scheduler, which is expected not to allow processor stay idle if there is any process ready or waiting for its execution. A process is allowed to utilize CPU resources for a fixed quantum of time (timeslice) and subsequent context switch leads to considerable overhead. In this work we try to utilize the historical performances of a scheduler and try to reduce the number of redundant context switches. We propose a machine-learning module, based on temporally extended reinforcement-learning agent, to predict a better performing timeslice. We measure the importance of states, in option framework, by evaluating the impact of their absence and propose an algorithm to identify such checkpoint states. We present empirical evaluation of our approach in a maze-world navigation and their implications on "adaptive time slice parameter" show efficient throughput time.
TEMPORALLY EXTENDED ACTIONS FOR REINFORCEMENT LEARNING BASED SCHEDULERSijscai
Temporally extended actions have been proved to enhance the performance of reinforcement learning
agents. The broader framework of ‘Options’ gives us a flexible way of representing such extended course of
action in Markov decision processes. In this work we try to adapt options framework to model an operating
system scheduler, which is expected not to allow processor stay idle if there is any process ready or waiting
for its execution. A process is allowed to utilize CPU resources for a fixed quantum of time (timeslice) and
subsequent context switch leads to considerable overhead. In this work we try to utilize the historical
performances of a scheduler and try to reduce the number of redundant context switches. We propose a
machine-learning module, based on temporally extended reinforcement-learning agent, to predict a better
performing timeslice. We measure the importance of states, in option framework, by evaluating the impact
of their absence and propose an algorithm to identify such checkpoint states. We present empirical
evaluation of our approach in a maze-world navigation and their implications on "adaptive timeslice
parameter" show efficient throughput time.
An adaptive algorithm for task scheduling for computational grideSAT Journals
Abstract
Grid Computing is a collection of computing and storage resources that are collected from multiple administrative domains. Grid resources can be applied to reach a common goal. Since computational grids enable the sharing and aggregation of a wide variety of geographically distributed computational resources, an effective task scheduling is vital for managing the tasks. Efficient scheduling algorithms are the need of the hour to achieve efficient utilization of the unused CPU cycles distributed geographically in various locations. The existing job scheduling algorithms in grid computing are mainly concentrated on the system’s performance rather than the user satisfaction. This research work presents a new algorithm that mainly focuses on better meeting the deadlines of the statically available jobs as expected by the users. This algorithm also concentrates on the better utilization of the available heterogeneous resources.
Keywords: Task Scheduling, Computational Grid, Adaptive Scheduling and User Deadline.
An enhanced adaptive scoring job scheduling algorithm with replication strate...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJCER (www.ijceronline.com) International Journal of computational Engineeri...ijceronline
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Efficient Dynamic Scheduling Algorithm for Real-Time MultiCore Systems
1. IOSR Journal of Computer Engineering (IOSR-JCE)
e-ISSN: 2278-0661,p-ISSN: 2278-8727, Volume 17, Issue 6, Ver. I (Nov – Dec. 2015), PP 77-86
www.iosrjournals.org
DOI: 10.9790/0661-17617786 www.iosrjournals.org 77 | Page
Efficient Dynamic Scheduling Algorithm for Real-Time Multi-
Core Systems
Pratap Suryawanshi1
, Radhakrishna Naik2
, Ishwar Chaudhary3
1,2,3
(Computer Science and Engineering Department, Marathwada Institute of Technology, India)
Abstract : Imprecise computation model is used in dynamic scheduling algorithm having heuristic function to
schedule task sets. A task is characterized by ready time, worst case computation time, deadline and resource
requirements. A task failing to meet its deadline and resource requirements on time is split into mandatory part
and optional part. These sub-tasks of a task can execute concurrently on multiple cores, thus achieving
parallelization provided by the multi-core system. Mandatory part produces acceptable results while optional
part refines the result further. To study the effectiveness of proposed scheduling algorithm, extensive simulation
studies have been carried out. Performance of proposed scheduling algorithm is compared with myopic and
improved myopic scheduling algorithm. The simulation studies shows that schedulability of task split myopic
algorithm is always higher than myopic and improved myopic algorithm.
Keywords: Dynamic real time scheduling, heuristic, imprecise computation, multi-core, real time systems,
resource requirement.
I. Introduction
In real time systems, correct computational results generated on time are required for a system to work
properly [1]. With wide applications of real time systems need for high computing hardware platform is also
there. Multi-core systems are emerging rapidly in real time systems. Multi-core system has high computing
power, more reliability and low energy consumption which makes them suitable for real- time systems. To
optimally exploit these high computing platforms efficient scheduling algorithms are also needed.
Many efficient algorithms are there which take processor requirement into consideration. Stankovic and
Ramamritham proposed heuristic scheduling algorithms which take processor requirement as well as resource
requirement into consideration [2]. Locking of resources and waiting of tasks might cause tasks to miss their
deadlines and thus reducing the predictability in real time systems [2]. In this paper dynamic scheduling
algorithm is developed which exploits the parallelization in tasks and strives to meet deadlines of tasks with
reduced computational complexity.
Optimal scheduling algorithms such as Rate Monotonic, Earliest Deadline First etc. do not take
resource requirement into consideration. Heuristic scheduling algorithm performs better than these algorithms.
Heuristic scheduling algorithm considers complete task set while searching for feasible schedule and hence has
a computational complexity of (O(n2
)). Myopic scheduling algorithm using heuristic function for scheduling
considers only three tasks of complete task set while searching for feasible schedule [3]. Myopic algorithm has
reduced complexity of (O(n)). Task split myopic algorithm developed in this paper has same computational
complexity as that of myopic algorithm but with higher schedulability and less slack times between tasks
executing on cores.
Parallelizable task scheduling algorithm in [4] exploits parallelization in periodic tasks to schedule task
sets. Performance of myopic algorithm on heterogeneous processors is show in [5]. Minimal earliest finish time
algorithm shows that processor having smallest earliest available time performs better. Effect of different
window size and processing times of tasks on the performance of algorithm is shown in [6]. Myopic algorithm
performs better with tasks having smaller processing times and performance further increases for larger window
sizes.
Main purpose of task split myopic algorithm is to exploit the parallelization provided by the multi-core
processing platform. Parallelization in task set is exploited through imprecise computation model which splits
task into mandatory sub-task and optional sub-task. Task not meeting its deadline is allowed to execute on
multiple cores, thus achieving parallelization and better utilization of all executing cores. Better utilization of
executing cores increases the probability of task meeting its deadline.
Rest of the paper is organized as follows; Section 2 gives brief information on background model. In
section 3, related work is discussed. In section 4, task split myopic scheduling algorithm is proposed. In section
5, case studies and simulation results are presented. In section 6, performance analysis of improved myopic and
task split myopic is illustrated. Section 7 concludes the paper.
2. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 78 | Page
II. Background
2.1 Multi-Core Processing Model
Multi-core processing model is assumed for scheduling proposed algorithm. A quad core processing
platform is considered having shared global memory. Core0 is reserved for scheduling and decision making also
called as scheduler while core1, core2 and core3 will be executing scheduled tasks also called as executing-cores.
In shared global memory model task are loaded into shared global memory and arrive at scheduler
(core0). Scheduler distributes these tasks to executing-cores for execution. The communication between
scheduler and executing-cores is through dispatch queues, each executing core has its dispatch queue. Scheduler
will be running in parallel with executing-cores scheduling newly arrived tasks and updating dispatch queues.
This organization ensures executing-cores will always find some tasks in dispatch queues when they finish
executing current tasks.
Executing-cores are of homogeneous kind and do not impose any relationship between them and tasks,
thus tasks are free to execute on any executing-core. Task finds a first available core among executing-core for
execution.
Task
Queue
hfeuighieug New Tasks Core 0
Scheduling Core Current Schedule
Core 1
Core 2
Core 3
Sorted Queue Feasible Schedule
Figure: 1 Multi-Core Architecture for Split Myopic Algorithm
1.2 Task Model
Tasks are dispatchable entities and have following notations:
Task arrival time, AT
Task deadline, DT
Task worst case execution time, PT
Task resource requirement, RT
Assumptions of tasks
Task consist of mandatory sub-task and optional sub-task
Tasks are independent, non preemptive and non-periodic
Task uses a resource either in shared mode or exclusive mode
For a schedule to be feasible following condition must be true for every task,
0 A EST D PT T T T …. (1)
where, ESTT is the earliest start time of a task
2.3. Terminology
i. Feasible Task: A task is said to be feasible if its timing constraints and resource requirements are met in the
schedule.
ii. Partial Schedule: A partial schedule is a feasible schedule for a subset of tasks. A partial schedule is said to
be strongly feasible if all the schedules obtained by extending the current schedule by any of the remaining tasks
are also feasible.
iii. ( )s kEAT EAT : It is the earliest time when resource R becomes available for shared (or exclusive) usage.
iv. ( )iEST T : It is the earliest start time of a task at which it can start its execution. Assume, ir is the ready
time of a task. C is the set of cores, iR be the resource requested by the task, ( )iEST T is given by,
( ) ( , ( ( )), ( ))i i j c kEST T MAX T Min availtime j MAX EAT …. (2)
3. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 79 | Page
( )iEST T where ( )availtime j denotes the earliest time at which the core jC becomes available for
executing a task and the third term denotes the maximum among the earliest available times of the resource
requested by task ( )iT , in which u s for shared mode and u e for exclusive mode.
v. LAXITY (T): Expresses the laxity degree of task T , it is given by,
( )
( )
D
C
T EST T
LAXITY T
T
.... (3)
vi. Mandatory sub-task: Sub-task ( ')iT of task ( )iT that is required to complete its execution before its
deadline to produce acceptable imprecise results.
vii. Optional sub-task: Sub-task ( '')iT of task ( )iT , refines the imprecise result upon its completion before its
deadline, but can be terminated at its deadline even if its execution is still going on.
viii. Upper Bound Utilization of Cores ( ( ))iUB C : Core ( )uC among executing cores having busy time
greater than other two cores is given by,
( ) ( , , )i j kUB T MAX C C C ….. (4)
where , ,i j kC C C are executing cores.
ix. Lower Bound Utilization of Cores ( ( ))iLB C : Core ( )lC among executing cores having busy time less
than other two cores is given by,
( ) ( , , )i j kLB T MIN C C C ….. (5)
where , ,i j kC C C are executing cores.
x. Middle Bound Utilization of Cores ( ( ))iMB C : Core ( )mC among executing cores having busy time in
between UB core and LB core is given by,
..… (6)
where , ,i j kC C C are executing cores.
III. Related Work
3.1 Imprecise Computation Model
If any time critical task fails to complete and produce results by its deadline, timing fault occurs.
Imprecise computation technique minimizes this difficulty; it achieves graceful degradation and produces
approximate results of acceptable quality [7].
Mandatory Sub-Task Optional Sub-Task
Figure: 2 Logical Decomposition of Task
Basic strategy is to minimize effect of timing faults by leaving less important tasks unfinished if
necessary. Imprecise Computation technique splits task into mandatory sub-task and optional sub-task.
Programmers structure every time critical task so that it can be logically decompose into mandatory sub-task
and optional sub-task [7]. Mandatory sub-task is required to complete its execution before deadline to generate
acceptable result. Optional sub-task refines this result. It can be left unfinished and can be terminated at its
deadline, if necessary.
The result produced by task which completes its execution before deadline is precise, has a zero error.
If the task is terminated before its completion, the intermediate result produced at that point is acceptable as long
as mandatory sub-task is complete. This intermediate result is called imprecise computation.
3.2 Efficient Dynamic Scheduling Algorithm for Multiprocessor Real Time System
Efficient scheduling algorithms based on heuristic functions were proposed by Ramamritham and
Stankovic. Following simple heuristic functions were compared,
Minimum Deadline First ( _ )Min D
Minimum Processing Time First ( _ )Min P
( ) i j kMB T C C C UB LB
4. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 80 | Page
Minimum Earliest Time First ( _ )Min S
Minimum Laxity First ( _ )Min L
Out of these functions ( _ )Min D performed better. Above simple heuristic functions were further
integrated to give better results. Integrated heuristic functions take resource requirement into consideration
while simple heuristic functions only consider processor requirement [2]. Following are the integrated heuristic
functions,
_ _Min D Min P
_ _Min D Min S
Among the above functions, _ _Min D Min S performs better.
3.3 Myopic Scheduling Algorithm
Myopic algorithm was also proposed by Ramamritham and Stankovic with a heuristic function which
considers deadline and resource requirements. At each search level myopic algorithm searches tasks within a
window for partial feasible schedule. In myopic algorithm partial schedule is extended by one of the remaining
task in a specified window and having best heuristic value.
Myopic algorithm has a reduced computational complexity of O(n) than original heuristic algorithm
O(n2
). Complexity is reduced due to limiting the search space for finding a feasible partial schedule.
{Tasks-remaining}: The tasks that remain to be scheduled. Tasks in {Tasks-remaining} are arranged
in the order of increasing deadlines.
rN : Number of tasks in {Tasks-remaining}.
k : Maximum number of tasks in Tasks-remaining considered for myopic scheduling algorithm
kN : Actual number of tasks in { Tasks-remaining} considered by the myopic algorithm at each step
of scheduling, given by,
min( , )k rN k N … (7)
{Tasks-considered}: The first kN tasks in {Tasks remaining}.
Termination conditions of algorithm are either,
A complete schedule is obtained.
Maximum number of backtracks or number of evaluations of H functions has been reached.
No more backtracking is possible.
3.4 Improved Myopic Scheduling Algorithm
Improved myopic scheduling algorithm was proposed by Zhu Xiangbin. Myopic algorithm does not
consider processing time while calculating heuristic value of task. Zhu Xiangbin added laxity parameter to
heuristic function. Due to this task having low laxity has a higher probability of getting processor time than task
with high laxity [8]. In improved myopic scheduling algorithm heuristic function was given by,
1 2( ) * ( ) * ( )DH T T W IEST T W Laxity T …... (8)
Steps in improved myopic scheduling algorithm,
Begin;
1) Order the task in non-decreasing order of their deadlines and then start with an empty partial schedule.
2) Determine whether the current vertex is strongly feasible by performing feasibility check for k tasks in the feasibility
check window. If the current vertex is strongly feasible, feasible=TRUE, otherwise, feasible=FALSE;
3) If (feasible is TRUE)
3.1) Computer the values of H function for all tasks in feasibility check window.
3.2) Extend the schedule by the task having the smallest H value.
4) Else
4.1) Backtrack to the previous search level.
4.2) Extend the schedule by the task having the next best H value
5) Move the feasibility check window by one task.
6) Repeat steps 2-5 until terminal condition is met.
End;
5. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 81 | Page
IV. Task Split Myopic Scheduling Algorithm
In this section proposed dynamic scheduling algorithm is discussed, which exploits parallelism present
in tasks to meet their deadlines. The proposed task split myopic algorithm is a variant of myopic scheduling
algorithm in [1]. Myopic or improved myopic algorithm checks first k tasks for feasibility, which is also
known as feasibility check window. Larger the size of feasibility check window, higher the scheduling cost.
The proposed scheduling algorithm is similar to myopic and improved myopic scheduling algorithm except that
it parallelizes task when there is not enough capacity left on core to meet that task’s deadline.
Steps in task split myopic scheduling algorithm,
Begin;
1) Order the task in non-decreasing order of their deadlines and then start with an empty partial schedule.
2) Determine whether the current vertex is strongly feasible by performing feasibility check for k tasks in the
feasibility check window. If the current vertex is strongly feasible, feasible=TRUE, otherwise, feasible=FALSE;
3) If (feasible is TRUE)
3.1) Computer the values of H function for all tasks in feasibility check window.
3.2) Extend the schedule by the task having the smallest H value.
4) Else
4.1) Split the task leading to infeasibility into mandatory sub-task and optional sub-task
4.2) Extend the schedule by the task having the next best H value
5) Move the feasibility check window by one task.
6) Repeat steps 2-5 until terminal condition is met.
End;
The termination conditions are either
1) A complete feasible schedule has been found or,
2) Maximum number of backtracks are reached or,
3) No more task splitting is possible
The heuristic function 1 2( ) * ( ) * ( )DH T T W IEST T W Laxity T is an integrated heuristic
which captures the deadline, resource requirement and laxity of a task [4]. The algorithm instead of backtrack
splits the task into mandatory sub-task and optional sub-task when the task cannot meet its deadline. Mandatory
sub-task will execute on earliest available core while optional sub-task will execute on second earliest available
core. Tasks use the required resource in shared or exclusive mode. Resource requirements are denoted as below,
1 2( (1), (2),..... ( ))R R R RNT T T T r , where
0, _ _ _ _RT T does not require resource
1, _ _ ( )_ _ _ modR iT T require resource R in shared e
2, _ _ ( )_ _ _ modR iT T require resource R in exclusive e
The complexity of proposed algorithm for scheduling non-periodic, non-preemptive tasks is O(kn)
which is same as that of myopic algorithm and improved myopic algorithm.
V. Performance Evaluation
To study the effectiveness of imprecise computation model in meeting task’s deadline, three case
studies have been stimulated. Here focus is on whether or not all the tasks in the task set finish before their
deadlines. Therefore the most important metric is success ratio, which is defined as number of task sets found
schedulable to the number of task sets considered for scheduling.
Here it is shown how the workload of task sets are distributed to the executing cores under the
influence of imprecise computation model in task split myopic scheduling algorithm. Another performance
metric considered is upper bound utilization which is defined as the time instance till which executing cores are
remaining busy while executing task sets. Low upper bound utilization denotes equal distribution of tasks to
executing cores and less time required to complete a task set.
Simulation Parameters
Three case studies, each with different scenario are simulated here. There are three executing cores and
two single instance resources ( 1R and 2R ). Values of 1 2,W W and number of task splits are fixed to 1, 1 and
2 respectively. Textured boxes represent the mandatory sub-task while shaded boxes represent optional sub-task
in schedules obtained by task split myopic algorithm.
6. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 82 | Page
Simulation Notations
Task ID is denoted by, IDi
Ready time of task, Ri.
Computation time of task, Ci.
Computation time of mandatory sub-task, Mi.
Computation time of optional sub-task, Oi.
Deadline of task, Di.
Resource requirement of task, RESi.
Generation of Tasks
i) The computation time iC of task iT is randomly chosen between _ (1)Min C and _ (50)Max C .
ii) The deadline of each task iT is randomly chosen in the range computation time at max, maxC and
maxC R , where R , is the simulation parameter also called as laxity parameter and
max Re _ ( )i iC ady Time R C ….… (10)
iii) The resource requirements of a task are generated based on the input parameters USeP and ShareP.
5.1 Case Study 1
Table 1: Task Set 1
In case study I there are six tasks having resource requirements. Their parameters are shown in Table 1.
At the first node, feasibility check window is having tasks T1, T2 and T3 task with best heuristic value (T1) will
be selected and it will execute on core1. At this stage first partial feasible schedule is obtained, now the window
will have tasks T2, T3, T4, again task T2 is having best heuristic value, so it will execute on core2. Feasibility
window will move by one step having tasks T3, T4, T5, T3 is having best heuristic value, it will execute on core3,
and so on.
Figure 3: Feasible schedule of improved myopic for case study I
Figure 4: Feasible schedule of task split myopic for case study I
IDi Ri Ci Mi Oi Di RESi
1 0 10 5 5 12 2
2 0 8 4 4 18 1
3 0 20 10 10 28 0
4 6 15 8 7 34 2
5 8 4 2 2 43 1
6 15 23 12 11 52 0
7. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 83 | Page
Fig. 3 represents the schedule obtained by improved myopic algorithm while Fig. 4 represents the
schedule obtained by task split myopic algorithm. Both are feasible schedules. In Fig. 4 every task executes its
sub-tasks in sequential manner or mandatory and optional sub-task are executing on single core for every task
because no task in schedule is leading to infeasibility. Tasks in task set are meeting their deadlines after
scheduling them with improved myopic or task split myopic. Upper bound utilization is 38 time units for both
scheduling algorithms.
5.2 Case Study II
Table 2: Task set 2
IDi Ri Ci Mi Oi Di RESi
1 0 10 5 5 12 2
2 0 14 7 7 18 1
3 0 27 14 13 28 1
4 8 11 6 5 38 0
5 12 14 7 7 40 2
6 15 30 15 15 51 1
In second case there are again six tasks and their parameters are as shown in table 2. Below Fig. 5
represents the schedule obtained by improved myopic algorithm while Fig. 6 represents the schedule obtained
by task split myopic algorithm for case study II. Both are feasible schedules. In Fig. 3, while building schedule
at window T4, T5, T6, task T6 is leading to infeasibility so improved myopic algorithm will backtrack to next best
task in window, hence, T5 will execute first on earliest available core, then T6 will execute and lastly T4 will
execute, thus finding a feasible schedule.
Figure 5: Feasible schedule of improved myopic for case study II
Figure 6: Feasible schedule of task split myopic for case study II
In task split myopic algorithm while scheduling task set in case study II, task T6 is leading to
infeasibility as shown in Fig. 5, so it will be split and mandatory sub-task will execute on earliest available core
i.e. core1 and optional sub-task will execute on middle bound core i.e. core3. Upper bound utilization of cores is
45 time units for improved myopic algorithm while it is 42 time units for task split myopic algorithm.
8. Efficient Dynamic Scheduling Algorithm for Real-Time Multi-Core Systems
DOI: 10.9790/0661-17617786 www.iosrjournals.org 84 | Page
5.3 Case Study III
Table 3: Task set 3
IDi Ri Ci Mi Oi Di RESi
1 0 20 10 10 22 1
2 0 23 12 11 23 2
3 0 40 20 20 47 0
4 15 20 10 10 50 1
5 25 25 13 12 60 0
6 30 44 22 22 74 2
Third case study consists of six tasks and their parameters are shown in Table 3. Fig. 7 shows the
infeasible schedule obtained by improved myopic algorithm and Fig. 8 shows the feasible schedule obtained by
task split myopic algorithm for the task set in case study III.
Figure 7: Infeasible schedule of improved myopic for case study III
Figure 8: Feasible schedule of task split myopic for case study III
In Fig. 7, while building schedule at window T4, T5, T6, task T6 is leading to infeasibility so improved
myopic algorithm will backtrack to next best task in window, hence T5 will execute first on earliest available
core, then T6 will execute and lastly T4 will execute, but this T4 task also leading to infeasibility. Improved
myopic algorithm is not able to find feasible schedule even after backtrack for the task set in case study III. In
task split myopic algorithm while scheduling task set, task T6 is leading to infeasibility, so it will be split and
mandatory sub-task will execute on earliest available core i.e. core1 or core3 and optional sub-task will execute
on core1 or core3 whichever not used by mandatory sub-task. Upper bound utilization of cores is 74 time units
for improved myopic algorithm while it is 62 time units for task split myopic algorithm.
VI. Performance Analysis
Performance analysis of improved myopic algorithm and task split myopic algorithm is carried out on
the basis of three parameters namely, Upper bound utilization, success ratio and average waiting time of task
set.
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DOI: 10.9790/0661-17617786 www.iosrjournals.org 85 | Page
Upper bound utilization of executing cores is given by the core having highest busy time among three
executing cores. It also denotes time required by cores to finish execution of a task set.
Waiting time of task in a task set is given by, . . ( ) Re _ ( )i iW T EST T ady Time R .. (11)
It shows for much time task has to wait once it is ready till it gets scheduled.
Table 4: Comparative Study of Algorithms with respect to Upper Bound Utilization
UpperBoundUtilization
Algorithm
Case Study
Improved Myopic
(time units)
Task Split Myopic
(time units)
Case Study I 38 38
Case Study II 45 42
Case Study III 74 62
Figure 9: Upper Bound Utilization Analysis
Table 5: Comparative Study of Algorithms with respect to Average Waiting Time
AverageWaitingTime
Algorithm
Case Study
Improved Myopic
(time units)
Task Split Myopic
(time units)
Case Study I 1 1
Case Study II 3.5 1.3
Case Study III 4.16 2.5
Figure 10: Average Waiting Time Analysis