ECE482 - Introduction to Operating Systems Project 3: User Mode Scheduling in MINIX 3
ECE482 Introduction to Operating Systems Project 3
Goals of the project
• Kernel space implementation • Scheduling algorithms • Kernel parameters
1 Introduction
Two days… Already two days that you have submitted your work on the LemonDB system and still nothing, not even a word or an email. On this cold morning of November you slowly walk to your work under the light rain, lost in your thoughts. Why? Why is this Mr. Frown so mean? Your teammates had some very nice feedback, one of them has even been promoted. But on your side, nothing! As you feel overwhelmed by frustration, you mentally devise some strategies to approach Mr. Frown. You picture yourself confronting him and showing him how valuable your are to Lemonion Inc.. You anticipate every sentence he could pronounce and prepare a striking response.
Without even realising it you have arrived to your cubicle. Stimulated by this long introspection you decide to step into Mr. Frown’s office. Arrived at his door you lift your hand and are ready to knock when you indistinctively hear Mr. Frown pronouncing your name! You slowly stop your movement and notice an upset tone in his voice. Pretending you need to lace your shoes you bow down and keep listening, while looking around to ensure nobody notices you.
After a few seconds it becomes clear that Mr. Frown is very upset with you. Not with your work, just with you. Although his words are sometimes unclear it is evident that he is furious that you worked well! He is saying that you are arrogant and want his position! Astonished by the absurdity of the situation and Mr. Frown’s preposterous non-sense, you stand up and walk back to your desk. You slowly seat down and switch your computer on while trying to regain your composure. As the computer has completed the booting sequence you notice a new email from your friend Bob.
Date: Mon. 22 Nov. 2022, 09:34:24 +0800 From: bob@coolzone.it To: n00b@lemonion.com Subject: what’s up? Hi buddy, Hope you’re all good. What has Frown said about your work? Here the company is so great, we had a giant party yesterday night so we almost all slept here! Jim, our boss (and friend) just announced that he wanted to test something new and their might be some openings. Would be great to work together, same as in college. Jim is here today, feel free to pop in and have a chat, maybe you could join the new dev team… See you buddy! Bob Bob, Software Engineer at CoolZone IT solutions.
Knowing your time is counted at Lemonion Inc. you have nothing to loose, so you grab your bag and leave, hoping to catch this perfect boss, and never to return here.
As you enter in the building of CoolZone IT solutions, you are struck by the atmosphere: you see several groups of relaxed, laid back people. A bear feet man wearing a flowery swimming-suit passes in front of you, and starts talking with a girl at the front desk. After she has given him a large bag of golf clubs he leaves the building. You now walk to the desk and inquire about the CEO. At first it seems she cannot understand you, but all of a sudden she exclaims “You mean Jim? He is on the slide! He’ll be down soon…” Feeling confused by her answer you gaze at her until she directs your attention to your right. Following her sign you walk a few steps and discover a long spiral slide coming down from the fifth floor and ending up in a giant ball pit where your recognise your friend Bob. He seems to be playing (discussing?) with a woman with long hair. However as they exit the pit you notice that the woman also has a long beard, meaning she is probably not a woman.
Feeling awkward and not knowing what to do, you choose not to move and wait for Bod and the other person to walk to you. As they are approaching he introduces Jim, his boss. Jim starts the conversation saying “Hey man, how are you keeping?” Before you can answer he carries on “Heard you were working with this – censored – Frown. We were together in college, he was a real – censored –.” At least you have some common ground with Jim: you both hate Mr. Frown.
Jim speaks a lot, really a lot. Nothing seems to stop him. Although everything sounds confused in your mind you recollect that he offers you to work on a new project, but nothing is ready yet. So his conclusion is that someone needs to work on it, why not you? From what you understand he vaguely remembers that during his undergraduates studies he heard that lottery scheduling could almost be used for real time systems. He would like to use part of his new funding to test it and see if he could launch a new smartphone with a new Operating System based on Minix 3.
His idea would be to take Minix 3 kernel, implement lottery scheduling in it, do the same with Earliest Deadline First (EDF), and compare their performance. He concludes the conversation with those few words: “You can start now, go in the ROMS, grab a laptop, and code. Organise yourself as you want, take as much holidays, free time, breaks as you want. Only requirements are that the project is completed by the end of the first week of December and that you perfectly use our Gitea system. Cheers man!” On those words he runs to the pit, performs a somersault, and disappears among the balls.
Bob smiles and says “Welcome to CoolZone IT solutions! Follow me to the ROMS, our Rest, Organize and Manage Space.” On your way to the ROMS Bob gives you a few more details regarding the project and how cool Jim is on everything but git! As this is much information you cannot fully understand everything but for sure you get that Jim wants you to perfectly handle your development workflow: you must use different branches, take advantage of labels and milestones to better organise your issues. Bob looks at you, and says “OK buddy. That’s a lot to take, but don’t worry, here there is no Frown, so relax and enjoy.” While speaking he grabs a notebook on the massive table at the center of the ROMS, hands it to you, and continues “Those are my notes, everything you need to know to work on the project. Hope you remember how to read my terrible handwriting…” His last words are punctuated by his loud laugh, but he suddenly stops and give a circular look at the room. Then he moves back toward the door, grabs another notebook, and triumphantly announces “Here, it is! The company’s directory. It seems Sylvia has already added you! So you can start working and catch your teammates as soon as you see them, some are not coming often so don’t hesitate to ask around.” On those words Bod greets you and leaves the room. As few seconds later he is back. He says “Sorry, forgot to explain about the notebook. We use different colors: blue for default tasks, orange for higher priority ones, and green for less pressing ones. So make sure to cover at least all the orange tasks!”1 After blinking his left eye to confirm his trust in you he leave the ROMS for good.
As you have no idea on where to start you seat at the table, and face the door hoping someone will comes. After grabbing a laptop, booting it up, you notice an icon labeled Minix 3.2.1, and a document called Minix 3 scheduler.pdf. While the virtual machine running Minix boots up, you start reading the scheduler document. You have made it! Here you are, ready to work in a new company! Good luck for this new adventure…
