https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Operating_Systems_2014F%3A_Assignment_3 2026-06-03T00:40:32Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19391&oldid=prev 2014-10-08T18:45:56Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:45, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l17">Line 17:</td> <td colspan="2" class="diff-lineno">Line 17:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Solutions==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Solutions==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># SJF has the same turnaround time as FIFO when all of the jobs are the same size.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># SJF has the same turnaround time as FIFO when all of the jobs are the same size <ins style="font-weight: bold; text-decoration: none;">or the jobs monotonically increase in size (e.g., the shortest job arrives first, then the 2nd shortest job, then the 3rd and so on)</ins>.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">SJF delivers the same response times as RR when the scheduling quantum of RR is larger than the largest job to be serviced (so there is no preemption in RR) and when the jobs arrive in order of increasing job size.</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">As job lengths increase average response time goes up.  If the jobs are sorted in increasing job size order, then the n-th job's response time is equal to the sum of the execution time of all the previous n-1 jobs plus that of the current job.  Increasing the size of any job thus increases the response time for it and all larger jobs.</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">With RR, as quantum lengths increase response time increases because the time a process must wait for its next time slice (in the worst case) is proportional to the number of other processes and the maximum amount of time they can execute.  Thus on a system with n processes and a quantum size of Q a process will have to wait for Q(n-1) to respond to a request (in the worst case).</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers allocate resources on a per-process basis.  On a system that has only one user this isn&#039;t a factor; on a system with multiple users, however, it can be a problem because any user can increase their share of resources simply by running more processes.  Fair-share schedulers can allocate a fixed proportion of resources to each user, no matter how many processes they choose to run.  Fair-share schedulers have traditionally not been used for CPU time because of their greater complexity (because they must keep track of process groups rather than just processes); however the current Linux schedule, [http://en.wikipedia.org/wiki/Completely_Fair_Scheduler CFS], is a weighted fair share scheduler that does special accounting for blocked processes.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers allocate resources on a per-process basis.  On a system that has only one user this isn&#039;t a factor; on a system with multiple users, however, it can be a problem because any user can increase their share of resources simply by running more processes.  Fair-share schedulers can allocate a fixed proportion of resources to each user, no matter how many processes they choose to run.  Fair-share schedulers have traditionally not been used for CPU time because of their greater complexity (because they must keep track of process groups rather than just processes); however the current Linux schedule, [http://en.wikipedia.org/wiki/Completely_Fair_Scheduler CFS], is a weighted fair share scheduler that does special accounting for blocked processes.</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19390&oldid=prev 2014-10-08T17:51:03Z

<p><span dir="auto"><span class="autocomment">Solutions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:51, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l17">Line 17:</td> <td colspan="2" class="diff-lineno">Line 17:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Solutions==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Solutions==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">SJF has the same turnaround time as FIFO when all of the jobs are the same size.</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19389&oldid=prev 2014-10-08T17:50:04Z

<p><span dir="auto"><span class="autocomment">Solutions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:50, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l23">Line 23:</td> <td colspan="2" class="diff-lineno">Line 23:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers allocate resources on a per-process basis.  On a system that has only one user this isn't a factor; on a system with multiple users, however, it can be a problem because any user can increase their share of resources simply by running more processes.  Fair-share schedulers can allocate a fixed proportion of resources to each user, no matter how many processes they choose to run.  <del style="font-weight: bold; text-decoration: none;">Traditionally fair </del>share schedulers <del style="font-weight: bold; text-decoration: none;">are </del>not <del style="font-weight: bold; text-decoration: none;">so good </del>for <del style="font-weight: bold; text-decoration: none;">interactive performance, however, </del>because they <del style="font-weight: bold; text-decoration: none;">do not normally boost the priority </del>of processes <del style="font-weight: bold; text-decoration: none;">that have received input.  Note that </del>the current Linux schedule, [http://en.wikipedia.org/wiki/Completely_Fair_Scheduler CFS], is a weighted fair share scheduler that does special accounting for blocked processes.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers allocate resources on a per-process basis.  On a system that has only one user this isn't a factor; on a system with multiple users, however, it can be a problem because any user can increase their share of resources simply by running more processes.  Fair-share schedulers can allocate a fixed proportion of resources to each user, no matter how many processes they choose to run.  <ins style="font-weight: bold; text-decoration: none;">Fair-</ins>share schedulers <ins style="font-weight: bold; text-decoration: none;">have traditionally </ins>not <ins style="font-weight: bold; text-decoration: none;">been used </ins>for <ins style="font-weight: bold; text-decoration: none;">CPU time because of their greater complexity (</ins>because they <ins style="font-weight: bold; text-decoration: none;">must keep track </ins>of <ins style="font-weight: bold; text-decoration: none;">process groups rather than just </ins>processes<ins style="font-weight: bold; text-decoration: none;">); however </ins>the current Linux schedule, [http://en.wikipedia.org/wiki/Completely_Fair_Scheduler CFS], is a weighted fair share scheduler that does special accounting for blocked processes.</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19388&oldid=prev 2014-10-08T17:48:39Z

<p><span dir="auto"><span class="autocomment">Solutions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:48, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l23">Line 23:</td> <td colspan="2" class="diff-lineno">Line 23:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># MLFQ-type schedulers <ins style="font-weight: bold; text-decoration: none;">allocate resources on a per-process basis.  On a system that has only one user this isn't a factor; on a system with multiple users, however, it can be a problem because any user can increase their share of resources simply by running more processes.  Fair-share schedulers can allocate a fixed proportion of resources to each user, no matter how many processes they choose to run.  Traditionally fair share schedulers are not so good for interactive performance, however, because they do not normally boost the priority of processes that have received input.  Note that the current Linux schedule, [http://en.wikipedia.org/wiki/Completely_Fair_Scheduler CFS], is a weighted fair share scheduler that does special accounting for blocked processes.</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19387&oldid=prev 2014-10-08T17:17:33Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:17, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l22">Line 22:</td> <td colspan="2" class="diff-lineno">Line 22:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>#</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">Standard OS schedulers are not fair because they give more resources more quickly to some processes over others.  Fairness in scheduling is normally defined as giving equal shares of CPU time to each process.  With prioritization we have unfairness due to policy: some processes are marked as being more important than others, thus they get more resources in a more timely fashion.  Schedulers are also unfair in that they tend to prioritize interactive processes over other processes that have the same priority level.  We want schedulers to be unfair because some processes should be prioritized: when I am playing a game, I do not want a background virus check to cause the game to slow down.</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">MLFQ-type schedulers</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19384&oldid=prev 2014-10-08T14:23:25Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:23, 8 October 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l15">Line 15:</td> <td colspan="2" class="diff-lineno">Line 15:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Explain two ways in which standard OS schedulers (such as those in Linux or Windows) are not fair to processes and why this is a good thing!</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Explain two ways in which standard OS schedulers (such as those in Linux or Windows) are not fair to processes and why this is a good thing!</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [1] MLFQ-type schedulers are more common in systems with single users while systems that support multiple users tend to use more proportional share-type schedulers.  Why might this be?</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [1] MLFQ-type schedulers are more common in systems with single users while systems that support multiple users tend to use more proportional share-type schedulers.  Why might this be?</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">==Solutions==</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># If you define efficiency as the ratio between the amount of CPU time spent on OS services versus time spent running userspace programs, preemptive schedulers are always less efficient because they switch between processes more often and hence run the scheduler and do context switches more often.  Time spent running the scheduler and doing context switches is pure overhead.  If you define efficiency in terms of response time - how long it takes the system to respond to input - preemptive schedulers are always more efficient than non-preemptive schedulers because preemptive schedulers can quickly switch to the process/thread that needs to process the input.</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19261&oldid=prev 2014-09-24T12:36:20Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:36, 24 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">'''This assignment is not yet finalized.'''</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by midnight on Wednesday, September 24, 2014.  There 10 points in 7 questions.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by midnight on Wednesday, September 24, 2014.  There 10 points in 7 questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19255&oldid=prev 2014-09-19T02:20:08Z

<p><span dir="auto"><span class="autocomment">Questions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 02:20, 19 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l16">Line 16:</td> <td colspan="2" class="diff-lineno">Line 16:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] &quot;Preemptive schedulers are always less efficient than non-preemptive schedulers.&quot;  Explain how this statement can be true if you define efficiency one way and how it is false if you define efficiency another way.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] &quot;Preemptive schedulers are always less efficient than non-preemptive schedulers.&quot;  Explain how this statement can be true if you define efficiency one way and how it is false if you define efficiency another way.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Explain two ways in which standard OS schedulers (such as those in Linux or Windows) are not fair to processes and why this is a good thing!</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Explain two ways in which standard OS schedulers (such as those in Linux or Windows) are not fair to processes and why this is a good thing!</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># [1] MLFQ-type schedulers are more common in systems with single users while systems that support multiple users tend to use more <del style="font-weight: bold; text-decoration: none;">lottery</del>-type schedulers.  Why might this be?</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># [1] MLFQ-type schedulers are more common in systems with single users while systems that support multiple users tend to use more <ins style="font-weight: bold; text-decoration: none;">proportional share</ins>-type schedulers.  Why might this be?</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19254&oldid=prev 2014-09-19T02:08:36Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 02:08, 19 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&#039;&#039;&#039;This assignment is not yet finalized.&#039;&#039;&#039;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&#039;&#039;&#039;This assignment is not yet finalized.&#039;&#039;&#039;</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by midnight on Wednesday, September 24, 2014.  There 10 points in <del style="font-weight: bold; text-decoration: none;">?? </del>questions.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by midnight on Wednesday, September 24, 2014.  There 10 points in <ins style="font-weight: bold; text-decoration: none;">7 </ins>questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Submit your answers as a single text file named &quot;&lt;username&gt;-comp3000-assign3.txt&quot; (where username is your MyCarletonOne username).  The first four lines of this file should be &quot;COMP 3000 Assignment 3&quot;, your name, student number, and the date of submission.  You may wish to format your answers in [http://en.wikipedia.org/wiki/Markdown Markdown] to improve their appearance.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Submit your answers as a single text file named &quot;&lt;username&gt;-comp3000-assign3.txt&quot; (where username is your MyCarletonOne username).  The first four lines of this file should be &quot;COMP 3000 Assignment 3&quot;, your name, student number, and the date of submission.  You may wish to format your answers in [http://en.wikipedia.org/wiki/Markdown Markdown] to improve their appearance.</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_3&diff=19253&oldid=prev 2014-09-19T02:08:01Z

<p><span dir="auto"><span class="autocomment">Questions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 02:08, 19 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l10">Line 10:</td> <td colspan="2" class="diff-lineno">Line 10:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Questions==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Questions==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># [<del style="font-weight: bold; text-decoration: none;">3</del>] For <del style="font-weight: bold; text-decoration: none;">each </del>of the <del style="font-weight: bold; text-decoration: none;">following </del>workloads<del style="font-weight: bold; text-decoration: none;">, say which simple scheduling algorithm would be most appropriate </del>and <del style="font-weight: bold; text-decoration: none;">explain your choice.  Choose from </del>the <del style="font-weight: bold; text-decoration: none;">following algorithms </del>as <del style="font-weight: bold; text-decoration: none;">defined in Chapter 7 of the textbook: FIFO, SJF, STCF, </del>RR<del style="font-weight: bold; text-decoration: none;">.</del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># [<ins style="font-weight: bold; text-decoration: none;">1</ins>] For <ins style="font-weight: bold; text-decoration: none;">what types </ins>of <ins style="font-weight: bold; text-decoration: none;">workloads does SJF deliver </ins>the <ins style="font-weight: bold; text-decoration: none;">same turnaround times as FIFO?</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#<del style="font-weight: bold; text-decoration: none;">*</del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># [1] For what types of </ins>workloads and <ins style="font-weight: bold; text-decoration: none;">quantum lengths does SJF deliver </ins>the <ins style="font-weight: bold; text-decoration: none;">same response times </ins>as RR<ins style="font-weight: bold; text-decoration: none;">?</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#<del style="font-weight: bold; text-decoration: none;">*</del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">[1] What happens to response time with SJF as job lengths increase?</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">#*</del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">[2] What happens to response time with RR as quantum lengths increase?  Explain in words and write an equation that gives the worst-case response time, given N jobs.</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] &quot;Preemptive schedulers are always less efficient than non-preemptive schedulers.&quot;  Explain how this statement can be true if you define efficiency one way and how it is false if you define efficiency another way.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] &quot;Preemptive schedulers are always less efficient than non-preemptive schedulers.&quot;  Explain how this statement can be true if you define efficiency one way and how it is false if you define efficiency another way.</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># [2] Explain two ways in which standard OS schedulers (such as those in Linux or Windows) are not fair to processes and why this is a good thing!</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># [1] MLFQ-type schedulers are more common in systems with single users while systems that support multiple users tend to use more lottery-type schedulers.  Why might this be?</ins></div></td></tr> </table>

Soma