Operating System Simulator - Essay Example

Operating System Simulator - Manual Introduction The CPU process-scheduling simulator has been developed using Java language, a powerful and popular software development language. The simulator is aimed at simulating behavior, illustrates the characteristics, and features various CPU scheduling algorithms including the First Come, First Served (FCFS) algorithm, Shortest Job First (SJF) algorithm, and the Round Robin (RR) scheduling algorithm. This simulator can be run in any operating system environment including UNIX systems such as Linux, so long as Java Runtime environment is installed. However, the JRE, Java Runtime environment installed should be the latest, such as the Java Runtime Environment Version 1.6 (JRE 1.6). It also supports JRE version 1.2. Java as language offers various capabilities including running the application as a Java applet or as a java application. Therefore, this CPU process-scheduling simulator can be run either as a Java applet or as a Java application. This CPU process scheduling algorithm can be used to perform several experiments on different process scheduling algorithms. Tables of data, graphs, and Gantt charts in form of log files in HTML can be produced by the simulator at the end of each experimental run. One experiment can be carried out involving several processes, for instance, the experiment can be based on eight different CPU processes. The tabular data obtained for different CPU process scheduling algorithms can then be analyzed and important conclusions drawn. Graph or Gantt chart data obtained can also be analyzed. Comparison between the various CPU scheduling algorithms can be drawn and explained based on the analysis of such data and the conclusions arrived at. The statistic to be evaluated and analyzed from the experimental runs includes data on processes throughput, CPU burst times, I/O Burst times, Waiting times, Turn Around time, and the ratio of CPU Burst Times to Time to Ready plus CPU Burst time. As noted earlier, this CPU process-scheduling simulator supports various CPU scheduling algorithms such as First Come, First Served (FCFS), Shortest Job First (SJF), and the Round Robin algorithm (RR). This simulator manual report will aim at reporting on experiments carried on two CPU process scheduling algorithms; the First Come, First Served (FCFS) algorithm, and the Shortest Job First (SJF) CPU scheduling algorithm. The experiment will be carried out on eight processes for both the algorithms and the characteristics of bot the algorithms evaluated based on those processes. Graphs, Gantt charts, and table data for both the CPU scheduling algorithms will be drawn, analyzed, and evaluated. The evaluation and analysis to be carried out is aimed at illustrating the differences between the two CPU process-scheduling algorithms based on the data obtained. Normally, it is expected that, for the Shortest Job First SJF also referred to as the shortest remaining CPU burst time first, the process with the shortest CPU burst time is the one that is executed first. For the First Come, First Served CPU scheduling algorithm, the first job to arrive in the ready queue is the one that is executed first, and it must be executed to completion before any other process takes up the CPU. However, there are scenarios such when there is an I/O request, a process being executed in the First Come, First Served algorithm is returned to the waiting time and a new process in the queue is executed before the other process continues executing. This is known as context switching and they are normally two. In the Shortest Job First CPU scheduling algorithm, there are scenarios where more than one process with the shortest CPU burst time; more than one process have the same CPU burst time exist in the ready queue. In such cases, these processes are evaluated depending on the time each job or process arrived in the ready queue, this implies some sort of First Come, First Served CPU scheduling algorithm is implemented, and the job that arrived in the ready queue first is the one that is executed first. Definition First Come, First Served CPU process scheduling algorithm implies that process or jobs are executed depending on how they arrive in the CPU ready queue. It is such that the process the first request the CPU is executed first; the process that arrives first in the ready queue is the one that is first executed. Any new job that arrives in the process ready queue, whether its CPU burst time is shorter, goes or is appended at the tail end of the ready queue. The next job that is run is the one that is the first in the process ready queue. Normally, the First Come First Served (FCFS) CPU scheduling algorithm is non-preemptive. This implies that, when a job starts executing in the CPU, it runs until the end of its CPU burst time without being interrupted. Therefore, FCFS CPU scheduling algorithm does not allow for context a switching or preemptive processing. This scheduling algorithm is also referred to as the First In, First Out (FIFO) algorithm. With this type of algorithm, the total CPU waiting time is always longer as well as its turnaround time. This is because, a process or job that could otherwise have been executed within a very short time is made to wait until a process taking very long to be executed is completed, and is therefore very inefficient. It results in a situation known as the convoy effect. For instance, if there are n-1 jobs in a system that are Input/output bound and one job that is CPU bound, the I/O bound jobs quickly through the ready queue. They then suspend themselves while they wait for the I/O. Those jobs that are CPU bound arrive at the front –end of the queue and are executed until completion. The processes bound for I/O then rejoin the ready queue and wait on the CPU bound processes to run to completion. At this time, the I/O devices are idle. After the completion of the CPU bound processes, the other processes join the waiting queue to wait on the I/O processes once more. At this time, the CPU is idle. This is the convoy effect. On the other hand, the Shortest Job First algorithm schedules the job with the shortest time for computation first. Usually, this scheduling algorithm is used in batch system processing. This algorithm aims at minimizing the turnaround time (TT) and has the lowest Average waiting time (AWT). This algorithm is optimal if all the jobs are simultaneously available. It is of two types, preemptive, and non-preemptive. Preemptive SJF is such that, a short job or process in the CPU ready queue preempts the process being executed as long its computation time is less than the time remaining for the process being executed. The Non-preemptive SJF is such that, whether a process in the ready queue has a shorter computational time compared to the time remaining for the process being executed, it has to wait until that process runs to completion before it can take up the CPU. Implementing the Run Starting the Simulator To start the simulator, one needs to type run-ups in the windows command prompt and executing it. Alternatively, it can be started by double clicking on the runps.bat file. The simulator can only fail to start when no Java runtime environment is installed, or it is not set in the environment variables path. On certain occasions, the simulator may fail to run because the version installed is lower than JRE 1.2. This experiment is carried out in a windows environment, in this case, Windows 7. Operating the Simulator Carrying out the experiment To carry out the experiment, the simulator needs to be started. First, a configuration file needs to be created; this described the properties of the simulator. An experiment made of either one or more runs is created, and in this experiment, the simulator was then run. The experimental results were then logged on the experimental log. The information regarding the location of the experiment, and where the results of the experimental results will be output are contained in the configuration file. Configuration File: logdir . logfn logfile.doc quiet . imagename gifim user Tahany Fergany portable true run myrun exp myexp The experimental run is also made up of processes to be executed and the scheduling algorithms. In this scenario, eight processes are run under two scheduling algorithms including SJF and FCFS. To carry out the experiments, two files had to be created. The run file, which contains information about the variables for the SJF run and for the FCFS run is one of the files created. The results are output in form of graphs, tables, and Gantt chart. Process Scheduling for Tahany Fergany generated Thu Feb 23 14:14:28 EST 2012 Process Scheduling Simulator version 1.100L288 by S. Robbins supported by NSF grants DUE-9750953 and DUE-9752165. See http://vip.cs.utsa.edu/nsf for simulator information. Java version 1.6.0_17 OS Windows 7 version 6.1 22277819664 Configuration File: logdir . logfn logfile.doc quiet . imagename gifim user Tahany Fergany portable true run myrun exp myexp Number of Run Files: 1 -------------------- name myrun comment This is a sample experimental run file algorithm FCFS numprocs 10 firstarrival 3.0 interarrival constant 5.0 duration uniform 10.0 15.0 cpuburst constant 12.0 ioburst constant 9.0 basepriority 9.0 Number of Experiment Files: 1 -------------------- name myexp comment This experiment contains 2 runs run myrun algorithm FCFS key "First Come First Served" run myrun algorithm SJF key "Shortest Job First" Experimental Run Information for 1 Run myrun:    This is a sample experimental run file    Seed: 0   Algorithm: FCFS Group Processes First Arrival Interarrival Duration CPU Burst I/O Burst 1 10 3.0 constant 5.00 uniform 10.00 15.00 constant 12.00 constant 9.00 Experimental Runs For 1 Experiment Experiment Commentary Run Modifications myexp This experiment contains 2 runs myrun_1 algorithm FCFS key First Come First Served myrun_2 algorithm SJF key Shortest Job First Starting experiment of 2 runs from myexp Thu Feb 23 14:14:30 EST 2012 Starting run from myrun_1 Starting to run events using FCFS 46 events done in 10 milliseconds Thu Feb 23 14:14:30 EST 2012 Starting run from myrun_2 Starting to run events using SJF 46 events done in 10 milliseconds Event List at Time 133.31 Process Scheduling Simulator version 1.100L288 by S. Robbins  supported by NSF grants  DUE-9750953 and DUE-9752165. Last update: February 1, 2007 Color Depth: 24 Java Version: 1.6.0_17 OS: Windows 7 version 6.1 Log File Opened File name: logfile.doc Starting experiment of 2 runs from myexp  Experimental Run for myrun   46 events done in 10 milliseconds  Experimental Run for myrun   46 events done in 10 milliseconds History List at Time 133.31 Configuration entries read: 8 Local Configuration file: psconfig  User:             Tahany Fergany  Log directory:    .  Log file:         logfile.doc  Image name:       gifim  Runs read:        1 of 1  Experiments read: 1 of 1  Repeatable random numbers Thu Feb 23 14:14:41 EST 2012 Event list size is 0 at 133.31 Thu Feb 23 14:14:43 EST 2012 Number of new processes 0 at time 133.31 Thu Feb 23 14:14:44 EST 2012 Number of waiting processes 0 at time 133.31 Thu Feb 23 14:14:47 EST 2012 Number of processes 10 at time 133.31  ID   State   Started   Finished In CPU     Used    Total  Waiting   1   done       3.00      27.97      2    13.70    13.70       2.26   2   done       8.00     100.13      2    14.68    14.68      68.45   3   done      13.00      26.26      1    11.26    11.26       2.00   4   done      18.00      38.92      1    10.95    10.95       9.97   5   done      23.00     112.15      2    12.02    12.02      68.13   6   done      28.00      73.45      1    11.75    11.75      33.70   7   done      33.00      61.70      1    11.71    11.71      16.99   8   done      38.00      49.99      1    11.07    11.07        .92   9   done      43.00     125.25      2    13.10    13.10      60.15  10   done      48.00     133.31      2    12.16    12.16      64.15 Thu Feb 23 14:14:49 EST 2012 Number of ready processes 0 at time 133.31 Thu Feb 23 14:14:51 EST 2012 Number of finished processes 10 at time 133.31  ID      Started   Finished CPU Total    3       13.00      26.26      11.26    1        3.00      27.97      13.70    4       18.00      38.92      10.95    8       38.00      49.99      11.07    7       33.00      61.70      11.71    6       28.00      73.45      11.75    2        8.00     100.13      14.68    5       23.00     112.15      12.02    9       43.00     125.25      13.10   10       48.00     133.31      12.16 Thu Feb 23 14:14:54 EST 2012 proc time in time out   time reason     idle    1     3.00    15.00  12.00 io          3.00    3    15.00    26.26  11.26 terminate           1    26.26    27.97   1.70 terminate           4    27.97    38.92  10.95 terminate           8    38.92    49.99  11.07 terminate           7    49.99    61.70  11.71 terminate           6    61.70    73.45  11.75 terminate           2    73.45    85.45  12.00 io                  5    85.45    97.45  12.00 io                  2    97.45   100.13   2.68 terminate           9   100.13   112.13  12.00 io                  5   112.13   112.15    .02 terminate          10   112.15   124.15  12.00 io                  9   124.15   125.25   1.10 terminate          10   133.15   133.31    .16 terminate   7.90 Number of runs: 2 First Come First Served    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Shortest Job First    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Thu Feb 23 14:15:04 EST 2012 Bursts of Process 1 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     1.70 Thu Feb 23 14:15:07 EST 2012 Bursts of Process 2 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     2.68 Thu Feb 23 14:15:16 EST 2012 Information on Process 1    State: done       Arrival Time:              3.00    Completion Time:          27.97    Times In CPU:            2    CPU Time Total:           13.70    CPU Burst Projected:       6.00    CPU Burst Total:           1.70    CPU Burst Remaining:       1.70    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            13.70    Total Ready Wait Time:     2.26    Total Ready and CPU:      15.97    Fraction Waiting:        .85817    Total IO Wait Time:        9.00    Total Time in System:     24.97 Thu Feb 23 14:15:19 EST 2012 Information on Process 2    State: done       Arrival Time:              8.00    Completion Time:         100.13    Times In CPU:            2    CPU Time Total:           14.68    CPU Burst Projected:       6.00    CPU Burst Total:           2.68    CPU Burst Remaining:       2.68    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            14.68    Total Ready Wait Time:    68.45    Total Ready and CPU:      83.13    Fraction Waiting:        .17661    Total IO Wait Time:        9.00    Total Time in System:     92.13 Thu Feb 23 14:16:09 EST 2012 Bins: 10 Min: 0.00 Max: 80.00 Overflow: 1 Waiting Time Thu Feb 23 14:16:29 EST 2012 Bins: 10 Min: 0.00 Max: 1.00 Ratio of CPU Time to Ready Time Plus CPU Time Thu Feb 23 14:16:38 EST 2012 Bins: 10 Min: 0.00 Max: 200.00 Turnaround Time Thu Feb 23 14:17:00 EST 2012 Bins: 10 Min: 0.00 Max: 20.00 CPU Burst Times Thu Feb 23 14:18:51 EST 2012 Gantt Chart for Shortest Job First Event List at Time 133.31 Process Scheduling Simulator version 1.100L288 by S. Robbins  supported by NSF grants  DUE-9750953 and DUE-9752165. Last update: February 1, 2007 Color Depth: 24 Java Version: 1.6.0_17 OS: Windows 7 version 6.1 Log File Opened File name: logfile.doc Starting experiment of 2 runs from myexp  Experimental Run for myrun   46 events done in 10 milliseconds  Experimental Run for myrun   46 events done in 10 milliseconds Saving image gifim01.gif ...  done Saving image gifim02.gif ...  done Saving image gifim03.gif ...  done Saving image gifim04.gif ...  done Saving image gifim05.gif ...  done History List at Time 133.31 Configuration entries read: 8 Local Configuration file: psconfig  User:             Tahany Fergany  Log directory:  Log file:         logfile.doc  Image name:       gifim  Runs read:        1 of 1  Experiments read: 1 of 1  Repeatable random numbers Thu Feb 23 14:14:41 EST 2012 Event list size is 0 at 133.31 Thu Feb 23 14:14:43 EST 2012 Number of new processes 0 at time 133.31 Thu Feb 23 14:14:44 EST 2012 Number of waiting processes 0 at time 133.31 Thu Feb 23 14:14:47 EST 2012 Number of processes 10 at time 133.31  ID   State   Started   Finished In CPU     Used    Total Waiting   1   done       3.00      27.97      2    13.70    13.70       2.26   2   done       8.00     100.13      2    14.68    14.68      68.45   3   done      13.00      26.26      1    11.26    11.26       2.00   4   done      18.00      38.92      1    10.95    10.95       9.97   5   done      23.00     112.15      2    12.02    12.02      68.13   6   done      28.00      73.45      1    11.75    11.75      33.70   7   done      33.00      61.70      1    11.71    11.71      16.99   8   done      38.00      49.99      1    11.07    11.07        .92   9   done      43.00     125.25      2    13.10    13.10      60.15  10   done      48.00     133.31      2    12.16    12.16      64.15 Thu Feb 23 14:14:49 EST 2012 Number of ready processes 0 at time 133.31 Thu Feb 23 14:14:51 EST 2012 Number of finished processes 10 at time 133.31  ID      Started   Finished CPU Total    3       13.00      26.26      11.26    1        3.00      27.97      13.70    4       18.00      38.92      10.95    8       38.00      49.99      11.07    7       33.00      61.70      11.71    6       28.00      73.45      11.75    2        8.00     100.13      14.68    5       23.00     112.15      12.02    9       43.00     125.25      13.10   10       48.00     133.31      12.16 Thu Feb 23 14:14:54 EST 2012 proc time in time out   time reason     idle    1     3.00    15.00  12.00 io          3.00    3    15.00    26.26  11.26 terminate           1    26.26    27.97   1.70 terminate           4    27.97    38.92  10.95 terminate           8    38.92    49.99  11.07 terminate           7    49.99    61.70  11.71 terminate           6    61.70    73.45  11.75 terminate           2    73.45    85.45  12.00 io                  5    85.45    97.45  12.00 io                  2    97.45   100.13   2.68 terminate           9   100.13   112.13  12.00 io                  5   112.13   112.15    .02 terminate          10   112.15   124.15  12.00 io                  9   124.15   125.25   1.10 terminate          10   133.15   133.31    .16 terminate   7.90 Number of runs: 2 First Come First Served    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Shortest Job First    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Thu Feb 23 14:15:04 EST 2012 Bursts of Process 1 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     1.70 Thu Feb 23 14:15:07 EST 2012 Bursts of Process 2 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     2.68 Thu Feb 23 14:15:16 EST 2012 Information on Process 1    State: done       Arrival Time:              3.00    Completion Time:          27.97    Times In CPU:            2    CPU Time Total:           13.70    CPU Burst Projected:       6.00    CPU Burst Total:           1.70    CPU Burst Remaining:       1.70    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            13.70    Total Ready Wait Time:     2.26    Total Ready and CPU:      15.97    Fraction Waiting:        .85817    Total IO Wait Time:        9.00    Total Time in System:     24.97 Thu Feb 23 14:15:19 EST 2012 Information on Process 2    State: done       Arrival Time:              8.00    Completion Time:         100.13    Times In CPU:            2    CPU Time Total:           14.68    CPU Burst Projected:       6.00    CPU Burst Total:           2.68    CPU Burst Remaining:       2.68    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            14.68    Total Ready Wait Time:    68.45    Total Ready and CPU:      83.13    Fraction Waiting:        .17661    Total IO Wait Time:        9.00    Total Time in System:     92.13 Configuration File: logdir.  logfn logfile.doc  quiet.  imagename gifim  user Tahany Fergany  portable true  run myrun  exp myexp-------------------- Thu Feb 23 14:16:09 EST 2012 Bins: 10 Min: 0.00 Max: 80.00 Overflow: 1 Waiting Time Thu Feb 23 14:16:29 EST 2012 Bins: 10 Min: 0.00 Max: 1.00 Ratio of CPU Time to Ready Time Plus CPU Time Thu Feb 23 14:16:38 EST 2012 Bins: 10 Min: 0.00 Max: 200.00 Turnaround Time Thu Feb 23 14:17:00 EST 2012 Bins: 10 Min: 0.00 Max: 20.00 CPU Burst Times Thu Feb 23 14:18:51 EST 2012 Gantt Chart for Shortest Job First Event List at Time 133.31 Process Scheduling Simulator version 1.100L288 by S. Robbins  supported by NSF grants  DUE-9750953 and DUE-9752165. Last update: February 1, 2007 Color Depth: 24 Java Version: 1.6.0_17 OS: Windows 7 version 6.1 Log File Opened File name: logfile.doc Starting experiment of 2 runs from myexp  Experimental Run for myrun   46 events done in 10 milliseconds  Experimental Run for myrun   46 events done in 10 milliseconds Saving image gifim01.gif ...  done Saving image gifim02.gif ...  done Saving image gifim03.gif ...  done Saving image gifim04.gif ...  done Saving image gifim05.gif ...  done History List at Time 133.31 Configuration entries read: 8 Local Configuration file: psconfig  User:             Tahany Fergany  Log directory:  Log file:         logfile.doc  Image name:       gifim  Runs read:        1 of 1  Experiments read: 1 of 1  Repeatable random numbers Thu Feb 23 14:14:41 EST 2012 Event list size is 0 at 133.31 Thu Feb 23 14:14:43 EST 2012 Number of new processes 0 at time 133.31 Thu Feb 23 14:14:44 EST 2012 Number of waiting processes 0 at time 133.31 Thu Feb 23 14:14:47 EST 2012 Number of processes 10 at time 133.31  ID   State   Started   Finished In CPU     Used    Total  Waiting   1   done       3.00      27.97      2    13.70    13.70       2.26   2   done       8.00     100.13      2    14.68    14.68      68.45   3   done      13.00      26.26      1    11.26    11.26       2.00   4   done      18.00      38.92      1    10.95    10.95       9.97   5   done      23.00     112.15      2    12.02    12.02      68.13   6   done      28.00      73.45      1    11.75    11.75      33.70   7   done      33.00      61.70      1    11.71    11.71      16.99   8   done      38.00      49.99      1    11.07    11.07        .92   9   done      43.00     125.25      2    13.10    13.10      60.15  10   done      48.00     133.31      2    12.16    12.16      64.15 Thu Feb 23 14:14:49 EST 2012 Number of ready processes 0 at time 133.31 Thu Feb 23 14:14:51 EST 2012 Number of finished processes 10 at time 133.31  ID      Started   Finished CPU Total    3       13.00      26.26      11.26    1        3.00      27.97      13.70    4       18.00      38.92      10.95    8       38.00      49.99      11.07    7       33.00      61.70      11.71    6       28.00      73.45      11.75    2        8.00     100.13      14.68    5       23.00     112.15      12.02    9       43.00     125.25      13.10   10       48.00     133.31      12.16 Thu Feb 23 14:14:54 EST 2012 proc time in time out   time reason     idle    1     3.00    15.00  12.00 io          3.00    3    15.00    26.26  11.26 terminate           1    26.26    27.97   1.70 terminate           4    27.97    38.92  10.95 terminate           8    38.92    49.99  11.07 terminate           7    49.99    61.70  11.71 terminate           6    61.70    73.45  11.75 terminate           2    73.45    85.45  12.00 io                  5    85.45    97.45  12.00 io                  2    97.45   100.13   2.68 terminate           9   100.13   112.13  12.00 io                  5   112.13   112.15    .02 terminate          10   112.15   124.15  12.00 io                  9   124.15   125.25   1.10 terminate          10   133.15   133.31    .16 terminate   7.90 Number of runs: 2 First Come First Served    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Shortest Job First    Times CPU Entered:         15    Times Ready Queue Entered: 15    Times I/O Started:         5 Thu Feb 23 14:15:04 EST 2012 Bursts of Process 1 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     1.70 Thu Feb 23 14:15:07 EST 2012 Bursts of Process 2 at time 133.31      CPU Burst     IO Burst    1.    12.00         9.00    2.     2.68 Thu Feb 23 14:15:16 EST 2012 Information on Process 1    State: done       Arrival Time:              3.00    Completion Time:          27.97    Times In CPU:            2    CPU Time Total:           13.70    CPU Burst Projected:       6.00    CPU Burst Total:           1.70    CPU Burst Remaining:       1.70    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            13.70    Total Ready Wait Time:     2.26    Total Ready and CPU:      15.97    Fraction Waiting:        .85817    Total IO Wait Time:        9.00    Total Time in System:     24.97 Thu Feb 23 14:15:19 EST 2012 Information on Process 2    State: done       Arrival Time:              8.00    Completion Time:         100.13    Times In CPU:            2    CPU Time Total:           14.68    CPU Burst Projected:       6.00    CPU Burst Total:           2.68    CPU Burst Remaining:       2.68    Times Waiting For IO:    1    IO Burst Time:             9.00    CPU Time Used:            14.68    Total Ready Wait Time:    68.45    Total Ready and CPU:      83.13    Fraction Waiting:        .17661    Total IO Wait Time:        9.00    Total Time in System:     92.13 Configuration File: logdir.  logfn logfile.doc  quiet.  imagename gifim  user Tahany Fergany  portable true  run myrun  exp myexp-------------------- Works Cited Bhatt, Pramod CP. An Introduction to Operating Systems: Concepts and Practice. PHI Learning Pvt. Ltd., 2004. Print. Garrido, Jose M. Performance modeling of operating systems using object-oriented simulation: a practical introduction. Springer, 2000. Print. Garrido, Jose M. and Schlesinger, Richard. Principles of modern operating systems. Jones & Bartlett Learning, 2008. Print. McHoes, Ann M, Flynn, Ida M. Understanding Operating Systems. New York: Cengage Learning, 2010. Print. Read More