Microprocessors and Microsystems xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Microprocessors and Microsystems journal homepage: www.elsevier.com/locate/micpro Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor K. Prescilla a,⇑, A. Immanuel Selvakumar b a b Department of Electronics and Communication Engineering, Karunya University, Karunya Nagar, Coimbatore 641 114, India Department of Electrical and Electronics Engineering, Karunya University, Karunya Nagar, Coimbatore 641 114, India a r t i c l e i n f o Article history: Available online xxxx Keywords: Heterogeneous processors Multiprocessors Modified BPSO Novel BPSO Periodic tasks Scheduling Task assignment Real-time Systems a b s t r a c t Task assignment in a heterogeneous multiprocessor is a NP-hard problem, so approximate methods are used to solve the problem. In this paper the Modified Binary Particle Swarm Optimization (Modified BPSO) algorithm and Novel Binary Particle Swarm (Novel BPSO) Optimization are applied to solve the real-time task assignment in heterogeneous multiprocessor. The problem consists of a set of independent periodic task, which has to be assigned to a heterogeneous multiprocessor without exceeding the utilization bound. The objective is to schedule maximum number of tasks with minimum energy consumption. The execution times and deadlines of the tasks are assumed to be known. Here Modified BPSO performance is compared with Novel BPSO and Ant Colony Optimization algorithm (ACO). Experimental results show that Modified BPSO performs better than Novel BPSO and ACO for consistent utilization matrix and ACO performs better than Modified BPSO and Novel BPSO for inconsistent utilization matrix. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Scheduling of task in a real-time system is important, because many of them are implemented in critical application. Due to the need to handle, different computationally intensive applications that have diverse computational requirements by a real-time system, they incorporate heterogeneous multiprocessors. Multiprocessor in a real-time system consists of a number of tasks with different deadlines. Therefore selection of an appropriate task scheduling algorithm is central to the proper functioning of the system. Static scheduling has the ability to consider complex dependencies, communication delays, and resource contention among jobs when constructing the static schedule. It also guarantees absence of deadlocks and unpredictable delays. Scheduling of real-time tasks in multiprocessor systems can be solved by two steps (i) Task allocation to processors and (ii) Scheduling tasks on individual processors. Partitioning method is appropriate for task allocation to multiprocessors, because it reduces the complex multiprocessor scheduling into uniprocessor one. There are multiple objectives to be optimized for this problem. A heterogeneous Multiprocessor has two or more processors with different speed (or) memory space (or) special processing capabilities. Task assignment in a heterogeneous multiprocessor system is a multiobjective combinatorial optimization problem, ⇑ Corresponding author. Mobile: +91 9092412458. E-mail addresses: [email protected] (K. Prescilla), immanuel. [email protected] (A. Immanuel Selvakumar). which is NP hard [1]. Since it is an NP-hard problem, it cannot be solved within polynomial time, so approximate methods are used to get near-optimal solutions within reasonable time. Approximate algorithms are called heuristics [2]. In this paper, the heuristics selected to partition are Modified BPSO and Novel BPSO. 2. Problem statement Let s, f, X represent a minimization problem of task assignment for a heterogeneous multiprocessor system, where S represents the set of candidate schedules, f is the objective function which assigns an objective function value f(s) to each schedule s 2 S and X represents the constraint. The constraints are a task should be assigned to only one processor and the total utilization of each processor should not exceed unity. The goal is to find a globally optimal feasible solution s⁄, that is, a minimum energy feasible solution to the minimization problem. The tasks are assigned by partitioning approach. In partitioned scheduling problem each task is assigned to a specific processor and there is no inter-processor migration. The off-line version of the task assignment problem is considered, that is, determining each task’s processor assignment without exceeding each processor’s computing capacity and violating task deadlines. The computation times and deadlines of the given tasks are known a prior and will not change over time. The tasks are independent and thus there are no precedence constraints among them. And there is no inter-task communication. Let P = {P1, P2, . . . , Pm} denotes an arbitrary Heterogeneous Multiprocessor Platform with pre-emptive processors based on CMOS 0141-9331/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.micpro.2013.05.003 Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 2 K. Prescilla, A. Immanuel Selvakumar / Microprocessors and Microsystems xxx (2013) xxx–xxx technology. Each processor Pj is limited to operating only one instruction per clock cycle, and runs at variable speed according to the type of task it is performing. si,j denotes the clock frequency, i.e., the speed, of Pj for a particular task Ti,ei,j denotes the execution time for Ti on processor Pj. Hence, ei,j and si,j are correlated by: ei,j = ci/si,j, where ci is the number of clock cycles to execute Ti. The energy consumption of Ti on Pj per period, Ei,j, is given by: Ei;j ¼ Power i;j ei;j C ef s3i;j k 2 ! ei;j ¼ C ef k 2 ci s2i;j ð1Þ where Cef and k are constants [3,4]. Therefore, the energy consumption incurred by executing Ti on Pj is almost linearly related to the product of ci and s2i;j : Ei;j / ci s2i;j A Periodic Task Set T = {T1, T2, . . . , Tn} is comprised of n real-time tasks. A real-time task Ti is represented by the tuple (e, p) where is the estimated worst-case execution time (WCET) and p is the period. Ti generates an infinite sequence of task instances of execution time at most e time units each, with instances being generated exactly p time units apart, and each instance has a deadline p time units after its arrival. The task assignment problem consists of two objectives. The first one is called resource objective; that is, searching for a solution in which each of the tasks is assigned to a specific processor in such a way that the cumulative utilization of any processor does not exceed the utilization bound of the EDF algorithm [5]. This objective represents a decision problem which is proven to be NP-hard in [6]. The second one is called energy objective; that is, minimizing the cumulative energy consumption of all assigned tasks in a solution. The resource objective is given precedence over the energy objective. 3. Related work Xu and Parnas [7] explained why pre-run-time scheduling is essential if one wishes to guarantee that timing constraints will be satisfied in a large complex hard-real-time system. Braun et al. [8] gave a Comparison of Eleven Static Heuristics for Mapping a Class of Independent Tasks onto Heterogeneous Distributed Computing Systems. A collection of 11 heuristics from the literature has been selected, adapted, implemented, and analyzed under one set of common assumptions. The objective was to minimize the makespan. Aydin and Yang [9] addressed the problem of partitioning periodic real-time tasks in a multiprocessor platform by considering both feasibility and energy-awareness perspectives. Baruah [1] proves that the heterogeneous multiprocessor partitioning problem is intractable (NP-hard in the strong sense). The author proposed an efficient (i.e., polynomial-time) algorithm for solving the Task assignment problem (TAP). His algorithm6 transforms a TAP instance into an Integer Linear Programming (ILP) problem, and then applies an approximation technique based on the idea of LP relaxations to solve the ILP in polynomial time. This algorithm is guaranteed to be able to find a feasible assignment solution to the TAP instances that meet certain constraints. Khanesar et al. [10] proposed Novel Binary Particle Swarm Optimization algorithm. It has a new interpretation for the velocity of binary PSO. The main difficulty of older version of binary PSO which is choosing proper value for w is solved. The previous direction and previous state of each particle is also taken into account and helped finding good solutions for problems. Lee et al. [11] proposed Modified Binary Particle Swarm Optimization which adopts concepts of the genotype–phenotype representation and the mutation operator of genetic algorithms. Its main feature is that the BPSO can be treated as a continuous PSO. Chen et al. [12] presented a new algorithm based on ant colony optimization (ACO) meta-heuristic for solving the problem of determining whether a set of periodic tasks can be assigned to a set of heterogeneous processors without deadline violations. A local search heuristic that can be used by various meta-heuristics to improve the assignment solution is proposed and its time and space complexity is analyzed. 4. Binary Particle Swarm Optimization algorithms 4.1. Binary Particle Swarm Optimization (BPSO) Particle swarm optimization (PSO) was developed in 1995 by James Kennedy and Russell Eberhart. The PSO is a population based search algorithm based on the simulation of the social behavior of birds, bees or a school of fishes. PSO applies the concept of social interaction to problem solving. It uses a number of particles that constitute a swarm moving around in the search space looking for the best solution. Each particle is treated as a point in a N dimensional space which adjusts its ‘‘flying’’ according to its own flying experience as well as the flying experience of other particles. Each particle has fitness value and velocity directing the flight. Particles follow two current best solutions pbest and gbest. Each particle keeps track of its coordinates in the solution space which are associated with the best solution that has achieved so far by that particle. This value is called personal best, Pibest. Another value tracked by the PSO is the best value obtained so far by any particle in the neighborhood of that particle. This value is called Pgbest. The basic concept of PSO lies in accelerating each particle toward its pbest and the gbest locations, with a random weighted acceleration at each time step. The PSO process then is iterated a fixed number of times or until a minimum error based on desired performance index is achieved. In the binary PSO, the particle’s personal best and global best is updated as in real-valued version. The major difference between binary PSO with real-valued version is that velocities of the particles are defined in terms of probabilities that a bit will change to one. In binary PSO small numbers for Vmax promotes exploration. If Vmax = 0, then the search changes into a pure random search [13]. 4.2. Novel Binary Particle Swarm Optimization In this algorithm, Pibest the and Pgbest of the swarm are updated as in real-valued or binary version. The major difference between this algorithm and other version of binary PSO is the interpretation of velocity. Here, as in real-valued version of PSO, velocity of a particle is the rate at which the particle changes its bit’s value. There are two vectors for each particle, they are: ~ V 0j and ~ V 1j . ~ V 0j is the V 1j probability of the bits of the particle to change to zero while ~ is the probability that bits of particle change to one. The probability of change in jth bit of ith particle is defined as follows ( V ci;j ¼ V 1i;j ; if xi;j ¼ 0 ð2Þ V 0i;j ; if xi;j ¼ 1 V 0j and ~ V 1j is V ci;j is the velocity of particle. The update algorithm for ~ shown below. Consider that the jth bit of ith best particle is one, so to guide the bit jth of ith particle to its best position, the velocity of change to one ð~ V 0j Þ for that particle increases and the velocity of V 1j Þ decreases. The following rules are extracted change to zero ð~ from this concept. 1 0 0 dij;1 1 dij;1 If Pjibest ¼ 1 then dij;1 ¼ r1 c1 and dij;1 ¼ r 1 c1 Pjibest ¼ r 1 c1 ð4Þ If Pjgbest ¼ 1 then dij;2 ¼ r 2 c2 and dij;2 ¼ r 2 c2 ð5Þ If If Pjgbest ¼ 0 then ¼ 0 then 1 ¼ r 1 c1 and ð3Þ 1 0 1 dij;2 0 dij;2 ¼ r 2 c2 and ¼ r2 c2 ð6Þ 0 where dij ; dij are two temporary values, r1 and r2 are two random variable in the range of (0, 1) which are updated in each iteration. Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 3 K. Prescilla, A. Immanuel Selvakumar / Microprocessors and Microsystems xxx (2013) xxx–xxx Also c1 and c2 are two fixed variables which are determined by user. Then: 1 1 ð7Þ 0 dij;1 0 dij;2 ð8Þ V 1ij ¼ wV 1ij þ dij;1 þ dij;2 V 0ij ¼ wV 0ij þ þ where w is the inertia term. In this algorithm if the jth bit in the global best variable is zero or if the jth bit in the corre- sponding personal best variable is zero the velocity V 0ij is increased. And the probability of changing to one decreases with the same rate. In addition, if the jth bit in the global best variable is one V 1ij is increased and V 0ij decreases. In this approach previously found direction of change to one or change to zero for a bit is maintained and used, so particles make use of previously found direction. After updating velocity of particles, ~ V 0j V 1j , the velocity of change is obtained as in (2). A normaland ~ Fig. 1. Flow chart of the Novel BPSO with Local search algorithm. Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 4 K. Prescilla, A. Immanuel Selvakumar / Microprocessors and Microsystems xxx (2013) xxx–xxx ization process is also done. Using sigmoid function as introduced in (9). v 0i;j ðtÞ ¼ sigðv i;j ðtÞÞ ¼ 1=1 þ ev i;j ðtÞ ( X ij ðt þ 1Þ ¼ X ij ðtÞ; if r ij < V 0ij X ij ðtÞ; if r ij > V 0ij ð10Þ ð9Þ And then the next particles state is computed as follows: where X ij ðtÞ is the 2’s complement of Xij(t) (i.e.), if Xij = 0 then X ij ¼ 1 and if Xij = 1 then X ij ¼ 0. Here rij is a uniform random number Fig. 2. Flow chart of the Modified BPSO with Local search algorithm. Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 5 K. Prescilla, A. Immanuel Selvakumar / Microprocessors and Microsystems xxx (2013) xxx–xxx between 0 and 1. The inertia weight used here maintains the previous direction of bits of particle to the personal best bit or global best bit whether it is 1 or 0. As in real-valued PSO if the maximum velocity value considered is large, random search will happen. Small values for maximum velocity cause the particle to move less [10]. Here also the previous states of the bits of the particles are taken into account using Eq. (8). 4.3. Modified Binary Particle Swarm Optimization The Modified BPSO is described using the genotype and phenotype concept. The velocity and the binary position parameters of the original BPSO are corresponding to the genotype of position and phenotype of position of the Modified BPSO, respectively. The main difference between the PSO and the Modified BPSO is in the position update function. The next position of the BPSO is not influenced by the current position but influenced by the velocity only. This implies that when updating a position in the BPSO, it is meaningless to know where a particle is currently located in the binary search space. Because of this fact, it seems that velocity is a particle, even though the binary position already exists in the BPSO. In Modified BPSO, the concept is that, the velocity and the position of the original BPSO is taken as a particle and a solution is transformed by the sigmoid function. Let the velocity and the binary position of the original BPSO be a genotype xg,i,j and a phenotype xp,i,j, respectively. Then, the update functions of Modified BPSO are as follows [11]: v i;j ðt þ 1Þ ¼ wv i;j ðtÞ þ c1 Fig. 3. The number of task assigned for the three algorithms of consistent utilization matrix. R1 ðpbest;i;j xp;i;j ðtÞÞ þ c2 R2 ðg best;i;j xp;i;j ðtÞÞ ð11Þ where R1 and R2 are two random variable in the range of (0, 1) which are updated in each iteration. And c1 and c2 are two fixed variables which are determined by user. The value of c1 and c2 are fixed to 2 in this application xgi;j ðt þ 1Þ ¼ xgi;j ðtÞ þ v i;j ðt þ 1Þ xpi;j ðt þ 1Þ ¼ 0; if randðÞ P Sðxgi;j ðt þ 1ÞÞ 1; if randðÞ; < Sðxgi;j ðt þ 1ÞÞ ð12Þ ð13Þ where ðxgi;j ðt þ 1ÞÞ ¼ 1=1 þ exgij ðtþ1Þ Fig. 4. The number of task assigned for the three algorithms of inconsistent utilization matrix. ð14Þ 5. Implementation The algorithms are implemented on IntelÒ Core™ i3 CPU processor with 2.27 GHz processor speed and 2.87 GB usable RAM. Nine utilization matrices are generated commonly for both Modified BPSO, Novel BPSO and ACO algorithm. The utilization matrixes differ in (i) Number of processor (ii) Number of tasks (iii) Task heterogeneity and (iv) Processor heterogeneity. The algorithms are implemented on IntelÒ Core™ i3 CPU processor with 2.27 GHz processor speed and 2.87 GB usable RAM. The software used is MATLAB 7.6.0 (R2008a). The utilization matrix Unm stores the real numbers in the range [0–1], the value of ui,j denotes the maximum fraction of the computing capacity Pj of required to execute Ti. A consistent utilization matrix is generated by sorting each speed vector independently, with processor P0 always being the fastest and processor P(m1) the slowest. In contrast, inconsistent utilization matrices simulate the situation where processor Pj may be faster than processor Pk for some tasks and slower for others. These utilization matrices are left in the unsorted, random state as they are generated. The utilization matrix is created as in [12]. The quality of the solution is measured by the objective function f(s). Table 1 normalized cumulative energy consumption of all assigned tasks in solution S by the three algorithms. Problem instance Modified BPSO Novel BPSO ACO C1_P4_T100_HT_HP C2_P8_T60_HT_LP C3_P4_T80_LT_HP C4_P8_T50_LT_LP IC1_P5_T150_HT_HP IC2_P8_T60_HT_LP IC3_P4_T100_LT_HP IC4_P8_T60_LT_LP IC5_P5_T20_LT_LP 0.385581 0.014091 0.000802 0.000027 1 0.000036 0.001601 0.000064 0.000003 0.350896 0.013641 0.000758 0.000027 0.990991 0.000036 0.001603 0.000065 0 0.340215 0.015264 0.000782 0.000026 0.105714 0.004701 0.001606 0.000068 0.00001 Table 2 Average CPU time consumed by the three algorithms (s) to execute different problem instances. Problem instance Modified BPSO Novel BPSO ACO C1_P4_T100_HT_HP C2_P8_T60_HT_LP C3_P4_T80_LT_HP C4_P8_T50_LT_LP IC1_P5_T150_HT_HP IC2_P8_T60_HT_LP IC3_P4_T100_LT_HP IC4_P8_T60_LT_LP IC5_P5_T20_LT_LP 2.886 7.781 18.416 10.596 51.367 0.429 1.962 14.609 0.187 0.741 1.346 0.585 1.369 1.79 1.229 0.706 1.47 0.285 1.346 1.965 0.9 1.379 3.19 1.705 1.105 1.482 0.44 Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 6 K. Prescilla, A. Immanuel Selvakumar / Microprocessors and Microsystems xxx (2013) xxx–xxx Table 3 Quality of the solution for Modified BPSO, Novel BPSO and ACO and their ranks. S. no Problem instance Quality of the solution 1 2 3 4 5 6 7 8 9 Average rank C1_P4_T100_HT_HP C2_P8_T60_HT_LP C3_P4_T80_LT_HP C4_P8_T50_LT_LP IC1_P5_T150_HT_HP IC2_P8_T60_HT_LP IC3_P4_T100_LT_HP IC4_P8_T60_LT_LP IC5_P5_T20_LT_LP Modified BPSO Novel BPSO ACO Modified BPSO Novel BPSO ACO 80.4541 49.5371 72.4197 41.5300 149.0343 59.4796 98.0576 58.1572 20.4567 74.5028 48.5523 67.4512 39.5271 145.0415 59.4796 96.0564 54.1496 20.6010 75.5418 48.5610 68.4553 40.5229 150.0749 60.1955 98.0493 57.1311 20.4841 1 1 1 1 2 2 1 1 3 1 3 3 3 3 3 2 3 3 1 3 2 2 2 2 1 1 2 2 2 2 ECðsÞ f ðsÞ ¼ AwardðsÞ þ 1 MaxEC where ECðsÞ ¼ Pm Pn j¼1 s i¼1 Ei;j :Di;j Rank of the solution ; MaxEC ¼ ð15Þ Pn 2 i¼1 ci :Maxðsi;j Þ j ¼ 1; . . . ; Ei;j ¼ C i :S2i;j m and Award(s) is equal to the number of assigned tasks in solution s. Award(s) reflects the distance between solution s and a feasible solution. EC(s) is the cumulative energy consumption of all assigned tasks in solution s, and is normalized by the maximum possible energy consumption MaxEC. The Novel BPSO with Local search algorithm is implemented as shown in the Fig. 1. The Modified BPSO with Local search algorithm is implemented as shown in the Fig. 2. 6. Result and discussion The problem instance C1_P4_T100_HT_HP-represents first consistent matrix with four processors and 100 tasks with high task heterogeneity and high processor heterogeneity. IC1_P5_T150_HT_HP represents first inconsistent matrix with five processors and 150 tasks with high task heterogeneity and high processor heterogeneity. The number of particles for each problem instance is considered as equal to the number of processors in that problem instance. Each problem instance was run on Modified BPSO algorithm and ACO algorithm until convergence and on Novel BPSO algorithm for nine iterations with varying inertia ‘w’. For Novel BPSO algorithm, the inertia was initialized to 0.9 and it is reduced by 0.1 for each iteration. This is done to have smooth convergence. The number of task assigned by Modified BPSO for problem instances of consistent utilization matrix is more when compared to Novel BPSO and ACO implementation. The number of task assigned by ACO for problem instances of inconsistent utilization matrix is slightly more when compared to Novel BPSO and Modified BPSO. The performance of Modified BPSO is better than Novel BPSO in all cases. This is because; the position update of the Modified BPSO uses the information of the current position and the velocity. The Novel BPSO and Modified BPSO require a trained input to get good solutions. The input given to the Modified BPSO Algorithm is a trained input from Ant Colony Optimization. One of the disadvantages of BPSO is slow convergence in refined search stage. So it requires a trained input and more number of iterations for convergence. ACO does not require a trained input. It is capable of training on self. So it requires less number of iterations for convergence. Fig. 3 shows the comparison between the number of task assigned for the three algorithms of consistent utilization matrix. Fig. 4 shows the comparison between the number of task assigned for the three algorithms of inconsistent utilization matrix. Energy consumed is reduced for feasible solutions by using Local Energy algorithm for all the three optimization techniques. The CPU time taken for Modified BPSO is more compared to Novel BPSO and ACO. Table 1 shows the comparison between normalized cumulative energy consumption of all as assigned tasks in solution s by the three algorithms for different problem instances. Table 2 shows the comparison between average CPU time consumed by the three algorithms for different problem instances. Table 3 shows the quality of the solution and their corresponding ranks. 7. Conclusion This work has analyzed the performance of different heuristic algorithms, on scheduling heterogeneous multiprocessor platform. The major contribution of this work is the application of Modified BPSO combined with a local search algorithm for solving task assignment in heterogeneous multiprocessor platform. The task assignment problem for a heterogeneous multiprocessor is solved using modified particle swarm optimization and Novel Binary Particle Swarm Optimization algorithm and it is compared with Ant Colony Optimization algorithm. This was done to find the best suitable algorithm for this application. The results show that modified particle swarm optimization assigns more number of tasks for problem instances with consistent utilization matrix, when compared to ACO. But Modified BPSO gives slightly lower performance for inconsistent utilization matrix compared to ACO. This is because BPSO has weak local search ability. The Modified BPSO performance is higher compared to Novel BPSO for both consistent and inconsistent utilization matrix. This is because; the position update of the Modified BPSO uses the information of the current position and the velocity. Energy optimization is done for feasible solutions found by all the algorithms. In the case of objective function maximization (i.e. energy minimization) MBPSO performs better for most of the problem instances. But MBPSO takes more time to solve the problem instance. Since the problem considered is offline scheduling the increase in execution time can be tolerated. The execution time of the algorithms on nine different problem instances are simulated using MATLAB 7.6.0 (R2008a). The average execution time taken for Modified BPSO is more compared to Novel BPSO and ACO because the number of iterations required to get the optimum result is more compared to other algorithms. References [1] S. Baruah, Task partitioning upon heterogeneous multiprocessor platforms, Real-Time and Embedded Technology and Applications (2004) 1–8. [2] Marco Dorigo, Thomas Stützle, Ant Colony Optimization, MIT Press, 2004. [3] T.D. Burd, R.W. Brodersen, Energy efficient CMOS microprocessor design, in: Proc. Hawaii Int’l Conf. System Science, January 1995, pp. 288–297. [4] D. Zhu, R. Melhem, B.R. Childers, Scheduling with dynamic voltage/speed adjustment using slack reclamation in multiprocessor real-time systems, IEEE Transactions on Parallel and Distributed Systems 14 (7) (2003) 686–700. [5] Albert M.K. Cheng, Real-Time Systems: Scheduling, Analysis, and Verification, John Wiley & Sons, 2002. Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003 K. Prescilla, A. 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[11] Sangwook Lee, Sangmoon Soak, Sanghoun Oh, Witold Pedrycz, Moongu Jeon, Modified binary particle swarm optimization, Progress in Natural Science 18 (2008) 1161–1166. [12] Hua Chen, Albert Mo Kim Cheng, Ying-Wei Kuo, Assigning real-time tasks to heterogeneous processors by applying ant colony optimization, Journal of Parallel Distributed Computing 71 (2011) 132–142. [13] J. Kennedy, R.C. Eberhart, A discrete binary version of the particle swarm algorithm, in: IEEE International Conference on Systems, Man, and Cybernetics, 1997. 7 K. Prescilla received the bachelor’s degree in Electrical and Electronics Engineering from Coimbatore Institute of Technology, India, in 2004. M.E. in Applied Electronics from Karunya University, India in 2006. She is currently pursuing her Ph.D. in real time systems under the supervision of Prof. Dr. A. Immanuel Selvakumar of Karunya University. Her research interest is scheduling in real-time systems. She has four years of teaching and research experience and she was a member of IEEE. A. Immanuel Selvakumar received the B.E. degree in Electrical and Electronics Engineering and M.E. degree in Power system Engineering from Thiagarajar College of Engineering, Madurai, India. He received Ph.D. degree in Electrical and Electronics engineering from Anna University, Chennai, India. His research topics include power system operation and control, soft computing techniques and meta-heuristic optimization techniques. He is a member of IEEE. He has presented eight papers in referred International Journals. Please cite this article in press as: K. Prescilla, A. Immanuel Selvakumar, Modified Binary Particle Swarm optimization algorithm application to real-time task assignment in heterogeneous multiprocessor, Microprocess. Microsyst. (2013), http://dx.doi.org/10.1016/j.micpro.2013.05.003
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