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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Dr. Foreback,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I think there might be an error in the second formula:<o:p></o:p></span></p>
<p class="MsoNormal">P3 turn around time = (24-3) = 31<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Should be:<o:p></o:p></span></p>
<p class="MsoNormal">P3 turn around time = (24-3) = 21<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I kept trying to get my code for average turnaround time to equal 22.67 and then recalculated everything.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">David<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> cs33211-bounces@cs.kent.edu [mailto:cs33211-bounces@cs.kent.edu]
<b>On Behalf Of </b>Dianne Foreback<br>
<b>Sent:</b> Friday, March 17, 2017 4:51 PM<br>
<b>To:</b> cs33211@cs.kent.edu<br>
<b>Subject:</b> [cs33211] Project 2 computing average wait time and turnaround time<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hello OS Class:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Project 1 output has a slight mistake for the FCFS average turnaround time. It should be 22.67.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I've had a couple questions on how to compute the average wait time and average turnaround time. My explanation relates to the FCFS scheduling algorithm using the input from project 1.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">pid<span class="gmail-apple-tab-span"> </span>arrival<span class="gmail-apple-tab-span">
</span>burst<span class="gmail-apple-tab-span"> </span><o:p></o:p></p>
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<p class="MsoNormal">---------------------<o:p></o:p></p>
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<p class="MsoNormal">1<span class="gmail-apple-tab-span"> </span>0<span class="gmail-apple-tab-span">
</span>10<span class="gmail-apple-tab-span"> </span><o:p></o:p></p>
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<p class="MsoNormal">2<span class="gmail-apple-tab-span"> </span>0<span class="gmail-apple-tab-span">
</span>9<o:p></o:p></p>
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<p class="MsoNormal">3<span class="gmail-apple-tab-span"> </span>3<span class="gmail-apple-tab-span">
</span>5<span class="gmail-apple-tab-span"> </span><o:p></o:p></p>
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<p class="MsoNormal">4<span class="gmail-apple-tab-span"> </span>7<span class="gmail-apple-tab-span">
</span>4<o:p></o:p></p>
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<p class="MsoNormal">5<span class="gmail-apple-tab-span"> </span>10<span class="gmail-apple-tab-span">
</span>6<o:p></o:p></p>
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<p class="MsoNormal">6<span class="gmail-apple-tab-span"> </span>10<span class="gmail-apple-tab-span">
</span>7<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The average wait time is the average amount of time each process waits in the readyQ.<o:p></o:p></p>
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<p class="MsoNormal">So, for each process the wait time is the time the process gets access to the CPU minus <o:p></o:p></p>
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<p class="MsoNormal">the time the process arrives.<o:p></o:p></p>
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<p class="MsoNormal">P1 wait time is (0 - 0) = 0<o:p></o:p></p>
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<p class="MsoNormal">P2 wait time is (10 - 0) = 10<o:p></o:p></p>
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<p class="MsoNormal">P3 wait time is (19-3) = 16<o:p></o:p></p>
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<p class="MsoNormal">P4 wait time is (24-7) = 17<o:p></o:p></p>
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<p class="MsoNormal">P5 wait time is (28-10) = 18<o:p></o:p></p>
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<p class="MsoNormal">P6 wait time is (34-10) = 24<o:p></o:p></p>
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<p class="MsoNormal">To get the average, add all of these together and divide by 6:<o:p></o:p></p>
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<p class="MsoNormal">(0+10+16+14+18+24)/6 = 14.17<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The average turnaround time is the average amount of time that it takes from the time it is<o:p></o:p></p>
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<p class="MsoNormal">submitted to the time it finishes. So, for our project, this is the average amount of time starting from when the process finishes minus the time the process arrives.<o:p></o:p></p>
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<p class="MsoNormal">P1 turn around time = (10-0) = 10<o:p></o:p></p>
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<p class="MsoNormal">P2 turn around time = (19-0) = 19 <o:p></o:p></p>
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<p class="MsoNormal">P3 turn around time = (24-3) = 31<o:p></o:p></p>
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<p class="MsoNormal">P4 turn around time = (28-7) = 21<o:p></o:p></p>
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<p class="MsoNormal">P5 turn around time = (34-10) = 24<o:p></o:p></p>
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<p class="MsoNormal">P6 turn around time = (41-10) = 31<o:p></o:p></p>
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<p class="MsoNormal">To get the average, add all of these together and divide by 6:<o:p></o:p></p>
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<p class="MsoNormal">(10 + 19+31+21+24+31)/6 = 22.67<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best,<o:p></o:p></p>
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<p class="MsoNormal">Dianne<o:p></o:p></p>
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