An-Najah Blogs :: Luai Malhis's Blog http://blogs.najah.edu/author/luai-malhis An-Najah Blogs :: Luai Malhis's Blog en-us Thu, 19 Jul 2018 20:33:25 IDT Thu, 19 Jul 2018 20:33:25 IDT webmaster@najah.edu webmaster@najah.edu A Systematic Approach for Building Processors in a Computer Design Lab Course at Universities in Developing Countrieshttp://blogs.najah.edu/staff/luai-malhis/article/A-Systematic-Approach-for-Building-Processors-in-a-Computer-Design-Lab-Course-at-Universities-in-Developing-CountriesPublished ArticlesThis paper presents a systematic technique for building processors by using off-the-shelf components The main objective of this methodology is to introduce computer engineering electrical engineering and computer science students in developing countries to all phases of CPU design using very primitive ICs and home made tool kits Using this technique students enrolled in processor design lab can design and build processors for a defined instruction with readily available components set at minimal cost The proposed methodology has been implemented in the computer engineering department at An-Najah National University and has proven to be efficient in teaching computer architecture and processor design as well as boosting computer-engineering students self-confidence without requiring them to use very advanced laboratory equipment Nevertheless the sole purpose of this technique and the objective of building this microprocessor is pure educational and is not to introduce a new methodology for building microprocessors for commercial purposes In this paper we will present our methodology by giving an instruction set example then describing the design and implementation steps followed In addition we also discuss the primitive components used to build the datapath the controller and the software tools used in both the implementation and testing phases We will show that the proposed methodology is very effective in providing students with the experience of microprocessor design without the need for advanced and expensive kits and devicesAn Educational Processor: A Design Approach http://blogs.najah.edu/staff/luai-malhis/article/An-Educational-Processor-A-Design-Approach-Published ArticlesIn this paper we present an educational processor developed at An-Najah National University This processor has been designed to be a powerful supplement for computer architecture and organization courses offered at the university The project is intended to develop an easily applicable methodology by which students get a valuable experience in designing and implementing complete processor with simple readily available off-the-shelf components The proposed methodology is beneficial to computer engineering students enrolled at universities specially in developing countries where advanced laboratory equipments are rarely available The design philosophy is to build a general-purpose processor using simple and wide spread integrated circuits This methodology includes: defining an instruction set datapath layout ALU implementation memory interface controller design and implementation For testing and evaluation purposes a debugging tool is also built and implemented to serially connect the processor to a personal computer In this paper we present the methods and components used in the design and implementation phases and the tools developed to complete the design process This methodology has shown that students enrolled in the computer architecture course get the full experience in processor design without the need for advanced laboratory equipments The components used are cost efficient and methods proposed allow students to work at home hence this methodology has proven to be cost effective and yet very educationalAn Efficient Two-Stage Iterative Method for the Steady-State Analysis of Markov Regenerative Stochastic Petri Net Modelshttp://blogs.najah.edu/staff/luai-malhis/article/AN-EFFICIENT-TWO-STAGE-ITERATIVE-METHOD-FOR-THE-STEADY-STATE-ANALYSIS-OF-MARKOV-REGENERATIVE-STOCHASTIC-PETRI-NET-MODELSPublished ArticlesTo enhance the modeling power of stochastic Petri nets SPNs new steady-state analysis methods have been proposed for nets that include non-exponential transitions Theunderlying stochastic process is a Markov regenerative process MRP when at most one non-exponential transition is enabled in each marking Time-efficient algorithms for constructing and solving the MRP have been developed However the space required to solve such models is often extremely large This largeness is due to the large number of transitions in the MRP Traditional analysis methods require that all these transitions be stored in primary memory for efficient computation If the size of available memory is smaller than that needed to store these transitions a time-efficient computation is impossible using these methods To use this class of SPNs to model realistic systems the space complexity of MRP analysis algorithms must be reduced In this paper we propose a new steady-state analysis method that is both time and space efficient The new method takes advantage of the structure of the underlying process to reduce both computation time and required memory The performance of the proposed method is compared to existing methods using several SPN examplesNumerical performability evaluation of a group multicast protocolhttp://blogs.najah.edu/staff/luai-malhis/article/Numerical-performability-evaluation-of-a-group-multicast-protocolPublished ArticlesMulticast protocols that provide message ordering and delivery guarantees are becoming increasingly important in distributed system design However despite the large number of such protocols little analytical work has been done concerning their performance especially in the presence of message loss This paper illustrates a method for determining the performability of group multicast protocols using stochastic activity networks a stochastic extension to Petri nets and reduced base model construction In particular we study the performability of one such protocol called Psync under a wide variety of workload and message loss probabilities The specific focus is on measuring two quantities the stabilization timethat is the time required for messages to arrive at all hostsand channel utilization The analysis shows that Psync works well when message transmissions are frequent but it exhibits extremely long message stabilization times when transmissions are infrequent and message losses occur We use this information to suggest a modification to Psync that greatly reduces stabilization time in this situation The results provide useful insights into the behaviour of Psync as well as serving as a guide for evaluating the performability of other group multicast protocolsNumerical evaluation of a group-oriented multicast protocol using stochastic activity networkshttp://blogs.najah.edu/staff/luai-malhis/article/NUMERICAL-EVALUATION-OF-A-GROUP-ORIENTED-MULTICASTPublished ArticlesGroup-oriented multicast protocols that provide message ordering and delivery guarantees are becoming increasingly important in distributed system design However despite the large number of such protocols little analytical work has been done concerning their performance especially in the presence of message loss This paper illustrates a method for determining the performability of group-oriented multicast protocols using stochastic activity networks a stochastic extension to Petri nets and reduced base model construction In particular we study the performability of one such protocol called Psync undera wide variety of workload and message loss probabilities The specic focus is on measuring two quantities the stabilization time|that is the time required for messages to ar rive at all hosts|and channel utilization The analysis shows that Psync works well when message transmissions are frequent but exhibits extremely long message stabilization times when transmissions are infrequent and message losses occur The results provide useful insight on the behavior of Psync as well as serve as a guide for evaluating the performability of other group-oriented multicast protocols Modeling recycle: a case study in the industrial use of measurementand modelinghttp://blogs.najah.edu/staff/luai-malhis/article/MODELING-RECYCLE-A-CASE-STUDY-IN-THE-INDUSTRIAL-USE-OFPublished ArticlesLarge-scale data storage systems rely on magnetic tape cartridges to store millions of data objects As these tapes age the resident data objects become invalid; consequently less and less of the tape potential capacity is effectively utilized To address this problem data storage systems have a facility called recycle in this paper that transfers valid data objects from sparsely populated tapes onto new tapes thus creating empty tapes for reuse A high performance recycle process is needed to keep the number of tape cartridges to a minimum and to maintain a continuous supply of empty tapes for storing newly created data objects The performance of such processes is not easy to determine and depends strongly on the data stored on the tapes the speed and characteristics of the computer on which recycle is executed and the nature of the algorithms themselves This paper documents an extensive report to evaluate a proposed recycle algorithm using field workload data laboratory measurements and modeling The results of the study were used to improve the recycle process and were later verified through field trials In addition yielding the results themselves the effort illustrated that modeling and measurement in an industrial setting can indeed be used successfully in the design process Dependability Evaluation Using Composed San-Based Reward Modelshttp://blogs.najah.edu/staff/luai-malhis/article/DEPENDABILITY-EVALUATION-USING-COMPOSED-SAN-BASED--REWARD-MODELSPublished ArticlesDependability evaluation is an important but difficult aspect of the design of fault-tolerant parallel and distributed computing systems One possible technique is to use Markov models but if applied directly to realistic designs this often results in large and intractable models Many authors have investigated methods to avoid this explosive state-space growth but have typically either solved the problem for a specic system design or required manipulation of the model at the state-space level Stochastic activity networks SANs a stochastic extension of Petri nets together with recently developed reduced base model construction techniques have the potential to avoid this state space growth at the SAN level for many parallel and distributed systems This paper investigates this claim by considering their application to three different systems: a fault-tolerant parallel computing system a distributed database architecture and a multiprocessor-multimemory system We show that this method does indeed result in tractable Markov models for these systems and argue that it can be applied to the dependability evaluation of many parallel and distributed systems