In your responses, critically review your peer’s analysis of the scenario and discuss whether or not your peer correctly identified the scheduling criteria conflicts that would occur. Indicate aspects of the post that effectively address the issues of CPU scheduling. Suggest additional issues (if any) not considered in your peer’s initial post. Describe a priority scheme that you would recommend to resolve these conflicts.
Response 1
Jesse Neubauer
Jun 3, 2021 at 7:50 PM
Describe a scenario where several systems are connected to a single printer through a network:
A single floor in a corporate office building will often share a single printer. Sometimes, access to that printer will be restricted to manager-level employees and above. Sometimes, every employee on the floor will have access to the printer. In my experience, jobs are sent to the printer from any workstation on the floor, and must be retrieved from the printer’s queue in person, by logging in to the printer’s interface (using the same credentials as the ones used on the workstation which transmitted the print job) and selecting the job to be printed. It is then printed on the spot, using whatever paper is currently loaded into the appropriate tray. Unclaimed print jobs will expire after an hour and be removed from the print queue.
Explain the scheduling criteria conflicts that would occur in the scenario that you described:
By requiring this secondary step of manually retrieving a job from the printer’s queue, most scheduling conflicts arise between users in person. A user will (usually) remain in the vicinity of the printer until their job is fully printed, which provides other users with a visual indicator that the printer is in use. This emulates the first-come-first-serve algorithm. If a user intends to print a large number of pages, it is courteous to check with the rest of the workers on the floor beforehand, to see if they have anything short/urgent to print first, so they won’t be left waiting a long time. This emulates a combination of shortest-job-first and priority-scheduling. If a user anticipates a printing job which will likely take several hours to complete, the user may break the job into chunks and send them as multiple jobs, in order to facilitate round-robin-scheduling – printing a chunk at a time, after allowing other users to print their jobs in between each chunk.
Indicate factors that would impede or improve overall utilization and performance:
The scenario described above is one which does not constantly put the printer to use. Employees on the floor with the single printer will likely have very rare occasion to need to print anything, meaning that overall utilization will be at a minimum, and performance will rarely be an issue. In a more busy scenario, such as a mail-generation room, it is far more likely to have multiple printers on the network, but it is also likely that the print jobs in such a scenario will be roughly equivalent in size and priority, meaning that first-come-first-serve scheduling will likely be employed.
Response 2
Joseph Shives
Jun 4, 2021 at 12:38 AM
Hi Everyone,
Several computers can be connected to the same printer through Wi-Fi. Printers often utilize first come, first serve basis (FCFS). This is where they execute based on how the printer receives the instructions. Another method is shortest job first (SJF). This means that the printer will execute whatever job takes the shortest amount of time. This would be optimal for larger environments, where a long printing job will slow down the rest of the environment. Priority scheduling executes jobs that are labelled as high priority first. This would be optimal in the emergency room. The prognosis and scans of a gun shot victim are more imperative than the discharge papers of a patient with a urinary tract infection. There are multiple conflicts that can occur through the printing process. For priority scheduling, each worker is in charge of designating what is most important. This doesn’t translate well when multiple people have various priorities. For instance, say it is 2 o’clock and you need these pamphlets for the 2:15 meeting. You would label something high priority. But, another worker is unaware of something you need, as they also need to print something for the 2:15 meeting. The computer would have 2 items that are labelled high priority. It would then become either first come, first serve or shortest job first. If it would be shortest job first, this is determined by an algorithm. Maybe one person is printing 30 of the same document that contains 4 sheets and another is printing 50 copies of a 2 page document. It might choose the 30 page document first then the 50 page document.
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