Management of Learning Resources with FCFS and SJF Scheduling Methods

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1 World Applied Programmig, Vol (), Issue (3), March ISSN: WAP joural. Maagemet of Learig Resources with FCFS ad SJF Schedulig Methods Mehdi Mohammadi Morshid Kheirollahi Rahmatollah Mohammadipour Sciece ad Research Brach, Islamic Azad Uiversity, Kermashah, Ira. Sciece ad Research Brach, Islamic Azad Uiversity, Kermashah, Ira. Kamra Malekia Mohammad Kazemi Nejad Parvi Sivaai Roya Basati Abstract: A basic factor which plays a crucial role i educatioal techology is learig resources. I every educatioal eviromet, limitatio of shared resources is oe of challegig issues; ad the eed for maagemet of curret resources emerges. I this paper, we are goig to have a survey o two methods (FCFS ad SJF) for sharig the resource amog the learers. These methods are quoted from Operatig Systems Schedulig Algorithms. Experimets show the better results of average wait time (AWT) ad average retur time (ART) for SJF. Keywords: educatioal techology, educatioal maagemet, learig resources, FCFS, SJF INTRODUCTION Educatioal techology, sometimes termed EdTech, is the study ad ethical practice of facilitatig e-learig, which is the learig ad improvig performace by creatig, usig ad maagig appropriate techological processes ad resources [1]. The term educatioal techology is ofte associated with, ad ecompasses, istructioal theory ad learig theory. While istructioal techology is "the theory ad practice of desig, developmet, utilizatio, maagemet, ad evaluatio of processes ad resources for learig," accordig to the Associatio for Educatioal Commuicatios ad Techology (AECT) Defiitios ad Termiology Committee [2], educatioal techology icludes other systems used i the process of developig huma capability. Educatioal techology icludes, but is ot limited to, software, hardware, as well as Iteret applicatios, such as wikis ad blogs, ad activities. But there is still debate o what these terms mea [3]. Techology i educatio is most simply ad comfortably defied as a array of tools that might prove helpful i advacig studet learig ad may be measured o how ad why idividuals behave. Educatioal Techology relies o a broad defiitio of the word "techology". Techology ca refer to material objects of use to humaity, such as machies or hardware, but it ca also ecompass broader themes, icludig systems, methods of orgaizatio, ad techiques. Some moder tools iclude but are ot limited to overhead projectors, laptop computers, ad calculators. Newer tools such as smart phoes ad games (both olie ad offlie) are begiig to draw serious attetio for their learig potetial. Media psychology is the field of study that applies theories of huma behavior to educatioal techology []. 97

2 Mehdi Mohammadi, et al. World Applied Programmig, Vol (), No (3), March 201. As a academic disciplie, the study of educatioal techology prepares idividuals by helpig them acquire a deeper uderstadig ad mastery of: Learig resources: messages, people, materials, devices, techiques ad settigs; Processes for aalyzig ad devisig solutios to those problems through research, theory, desig, productio, evaluatio, utilizatio; The processes ivolved i orgaizatio ad persoel maagemet. The focus is o effective processes to facilitate learig usig techologies ad uderstadig the impacts of techology o learers ad orgaizatios [5]. Learig resources are the basic factor of learig techology. We suppose a learig system with limited learig resources. Learers wat to take advatage from curret resources ad we wat to service them i the best way ad shortest wait time for each learer. I this paper we are goig to aswer the followig questio: How ca maage the learig resources that all the learers ca have the best service ad shortest wait time? Itroduced methods for schedule the learig equipmets are [6]: A. First Come First Serve (FCFS) B. Shortest Job First (SJF) I the follow, we will get ito each oe of these algorithms ad ivestigates its features for our purpose. FIRST COME FIRST SERVE (FCFS) First-come, first-served (FCFS) sometimes first-i, first-served ad first-come, first choice is a service policy whereby the requests of customers or cliets are atteded to i the order that they arrived, without other biases or prefereces. The policy ca be employed whe processig sales orders, i determiig restaurat seatig, o a taxi stad, etc. I Wester society, it is the stadard policy for the processig of most queues i which people wait for a service. The practice is also commo amog some airlies which do ot permit seat reservatios either i advace or at check-i. These airlies allow passegers to board i small groups based upo their order of check-i ad sit i whatever seat o the aircraft they wish to. O the basis of first come, first served, the earlier they check i, the earlier they board the aircraft to get the seat they wat. Passegers are sequetially (o a first come, first served basis) assiged ito oe of several "boardig groups." The passegers are the boarded oto the plae i group order [7]. I learig eviromet, it ca be used to allocate the resources to learers. It may be oted here that FCFS is No- Preemptive. It meas that oce resource is allocated to a learer, the he/she will use it util whe it is eeded. SHORTEST JOB FIRST (SJF) Shortest Job First (SJF), also kow as Shortest Job Next (SJN), is a schedulig policy that selects the waitig learer with the smallest eedig time to resource ext [8]. SJF is a o-preemptive. It searches betwee the learers resource allocatio time [9] ad the give the resource to the oe with less time. Shortest job ext is advatageous because of its simplicity ad because it miimizes the average amout of time each learer has to wait util its allocatio is complete. However, it has the potetial for learers requests starvatio for those who eed the resource for a log time to complete if short time allocatios are cotiually added. Aother disadvatage of usig shortest job ext is that the total allocatio time of a job must be kow before resource allocatio. While sometimes it is ot possible to perfectly predict allocatio time [10]. 98

3 Mehdi Mohammadi, et al. World Applied Programmig, Vol (), No (3), March 201. Shortest job ext is used i specialized eviromets where accurate estimates of allocatio time are available. Estimatig the ruig time of queued learers is sometimes doe usig a techique called agig [11]. COMPARISON OF FCFS AND SJF I order to specify the efficiecy of SJF vs. FCFS, we decided to have a compariso betwee them. The criteria of this compariso are the average wait time (AWT) ad average retur time (ART). We suppose that there is just oe learig resource that must be shared amog learers. It ca be also exteded for may equipmets, but the purpose of cosiderig oe equipmet is for showig the way ad show the differece of FCFS ad SJF approaches to maage the resources allocatio to learers i a shared eviromet. Let learers (L1 to L) that eed allocatio time (T1 to T). Followig table shows the times. Table 1: Learers ad their allocatio times Order Learers Allocatio time 1 L L L3 70 L 0 Figure 1 shows the allocatio order based of FCFS: Wait (L2) L1 Wait (L3) Wait (L) L2 L3 L Figure 1: Resource allocatio based o FCFS 99

4 Mehdi Mohammadi, et al. World Applied Programmig, Vol (), No (3), March 201. Wait(L ) 0 Wait(L ) 60 Wait(L ) 10 Wait(L ) 210 AWT Wait(L ) Retur (L ) 60 Retur (L ) 200 Retur (L ) 10 Retur (L ) 660 ART Retur(L ) Wait (L2) L2 Wait (L3) L3 Wait (L1) L1 L Figure 2: Resource allocatio based o SJF Wait(L ) 0 Wait(L ) 170 Wait(L ) 100 Wait(L ) 0 AWT Wait(L ) Retur (L ) 100 Retur (L ) 250 Retur (L ) 170 Retur (L ) 0 ART Retur(L ) Based o the results, it is vividly see that SJF performs better i AWT ad ART. 100

5 Mehdi Mohammadi, et al. World Applied Programmig, Vol (), No (3), March 201. DISCUSSION ON FEATURES OF FCFS AND SJF Totally, the summary of preseted cotet of this paper is show i table 2 [12]. Table 2: Compariso of FCFS ad SJF Parameter FCFS SJF Preemptio o preemptive preemptive Complexity Very simple More difficult tha FCFS Allocatio Allocates the resource i the order i which the learers arrive. Allocates the resource to the learer with least usage time. Waitig Time Average waitig time is large. Average waitig time is less. Retur Time Average retur time is large. Average retur time is less. Usability Not recommeded because performace is a major issue. Problems: It eeds to kow the legth of time for which the learers eed the resource. Log time learers may face with resource allocatio starvatio with addig short time learers to system. REFERENCES [1] Richey, R.C. (2008). Reflectios o the 2008 AECT Defiitios of the Field. TechTreds. 52(1) 2-25 [2] D. Rady Garriso ad Terry Aderso (2003). E-Learig i the 21st Cetury: A Framework for Research ad Practice. Routledge. ISBN [3] Lowethal, P. R., & Wilso, B. G. (2010). Labels do matter! A critique of AECT s redefiitio of the field. TechTreds, 5(1), doi: /s y [] Educatioal techology. Article available at: [5] What is educatioal techology?, Article available at: [6] Masoud Nosrati, Roak Karimi, Mehdi Hariri. Task schedulig Algorithms Itroductio. World Applied Programmig, 2(6), [7] "First-come, first-served", Article available at: [8] Arpaci-Dusseau, Remzi H.; Arpaci-Dusseau, Adrea C. (201), Operatig Systems: Three Easy Pieces [Chapter Schedulig Itroductio], Arpaci-Dusseau Books [9] Masoud Nosrati, Roak Karimi, Hojat Allah Hasavad. "Ivestigatio of the * (Star) Search Algorithms: Characteristics, Methods ad Approaches", World Applied Programmig, Volume 2 - Issue, pp [10] Silberschatz, A.; Galvi, P.B.; Gage, G. (2005). Operatig Systems Cocepts (7th ed.). Wiley. p ISBN [11] Taebaum, A. S. (2008). Moder Operatig Systems (3rd ed.). Pearso Educatio, Ic. p ISBN [12] Akur Bhardwaj, Rachhpal Sigh, Gaurav. Comparative Study of Schedulig Algorithms i Operatig System, Iteratioal Joural of Computers ad Distributed Systems, Vol. No.3, Issue I, April-May