CS4410/4411: Operating Systems

Fall 2010, Prof. Sirer


  • Dec 5: On the first day of class, I mentioned the Therac-25 incident from the 80s where errors in a synchronization primitive ended up killing people. It turns out radiation treatments still cause deaths due to computer errors. I'm confident none of your code will be involved in such mishaps.
  • Nov 26: TCP slow-start in the news. Apparently, some companies disable slow-start or else pick large initial window sizes to speed up the delivery of their home pages. Note the alternative description of slow-start: expanding the window size by 1 for every ack received is equivalent to doubling the window size once the entire window makes it to the other side without loss.
  • Nov 23: MP4 is out. MP4 is OPTIONAL for students in CS4411.
  • Nov 20: You should read Alex Slover's essay on how to test your programs: I Shall Not Mutate My Program, I Shall Use Correct Default Values, and Override Them by Passing Appropriate Command Line Parameters for Testing. (BTW, you should name the specific exception you're catching as in "except IOError,ioe:", and refrain from using the all-too-powerful "except:").
  • Nov 19: Di's monkeys wish you a Happy Thanksgiving (but only if your solution did not kill them!):
  • Nov 19: BGP in the news here and here.
  • Nov 17: Unofficial sample solutions for the triad problem are posted. The file contains a mix of elegant and correct, kludgy but correct, and incorrect solutions. A comment before each solution summarizes the problem with that solution. Keep in mind that the correctness of this code was not checked mechanically, so there may well be typos (in a transcription this long, we'd expect that) or we may have miscategorized the solution, so, as always, look at all code critically.
  • Nov 17: Unofficial sample solutions for MP3 essay questions are posted.
  • Nov 15: Ironically, there was a mail hiccup on our servers between 1:30am and 10am, as we tweaked our own mail servers to cut down on spam. Mail delivery has now been restored to its old settings. If your message to the course staff bounced earlier, please send it again and it should go through.
  • Nov 14: Additional clarifications in the MP3 FAQ. No changes to any spec, so no need to read if you are done with the assignment.
  • Nov 10: Prof. Sirer will be holding office hours today from 5-6pm.
  • Nov 5: We made a small clarification to the README in the CMS bundle; if you have been reading the MP3 FAQ, there is no need for you to update.
  • Nov 3: MP3 is REQUIRED for everyone registered in CS4410, including those of you who are also registered in 4411.
  • Nov 3: Clarifications about MP3 timeouts posted to the FAQ.
  • Nov 2: MP3 is out today, along with its FAQ The due date has been pushed back from Nov 11th to Nov 15th.
  • Nov 4: Prof. Sirer will be eating at the Oakenshield from 6:30pm onwards tonight. (We announced 7pm in class, but the dining hall apparently closes at 7:30).
  • Oct 31: The TCP three-way handshake illustrated:
  • Oct 31: In the scary Halloween spirit and even named appropriately: this is what happens when you let Hipsters mix with Goths. Get your synchronization right everyone, the world can only handle so many bad bands from the UK!
    The Horrors.
  • Oct 28: Some people were confused by the use of an optimization (where a Python None was used to simulate a page table entry with the valid bit set to False) in the MMU simulator. We have modified MP2 to not use this optimization. Those of you who picked up MP2 earlier should not have to change anything, and those of you picking it up now should now see the new code which should leave less room for misunderstanding the operation of an MMU. A second file shows the handful of lines that were affected. By the way, it's a good idea to check the MP2 FAQ periodically, as we post new information.
  • Oct 26: Tai Chen will be holding office hours Sun 4-6pm and Thu 7-9pm.
  • Oct 26: Michael George will be holding office hours MWF from 9-10am.
  • Oct 26: Per your feedback: we have additional TAs, as announced earlier, and we'll try to have them hold their office hours in the mornings and "off" days and hours.
  • Oct 25: Change to Final location now posted.
  • Oct 25: Histogram of MP1 grades:
  • Oct 23: There is now a MP2 FAQ, with some hints to guide you along.
  • Oct 23: Prof. Sirer is having second thoughts about his policy of not using Comic Sans, given conflicting evidence.
  • Oct 23: We have two additional PhD TAs! Welcome Tai Yang Chen and Michael George to the course staff.
  • Oct 23: MP1 grades are out. Please go over questions you missed; the TAs and I will be happy to go over your MP1s during office hours.
  • Oct 20: Per your feedback: those of you seeking additional readings or a different perspective can check out the optional supplemental textbook, as well as the supplemental readings.
  • Oct 20: Per your feedback: We've placed some additional synchronization questions and answers online. Those of you who missed some of the synchronization questions on Prelim I should have a go at these problems.
  • Oct 19: Per your feedback: for the record, Prof. Sirer has never knowingly used the "Comic Sans" font in his life. PowerPoint may have mapped a non-existent font to Comic Sans, or else Tahoma, Verdana or Arial exhibit some problems that bug at least one budding typographer. Please point these out and I'll be happy to fix them -- I use POwerpoint only for slides; the rest of the toolchains I use enforce typographic principles going back to Gutenberg.
  • Oct 19: Per your feedback: we've added PDF versions of the slide sets to the lectures page.
  • Oct 18: Deniz Altinbuken's Office Hours are cancelled this week.
  • Oct 14: MiniProject 2 has been released. It is OPTIONAL for students in CS4411, REQUIRED for students taking CS4410 but not CS4411.
  • Oct 14: Prelim I grades have been released on CMS. The grade distribution looks as follows:

    Please do not hesitate to talk to the course staff if you have any questions, but keep in mind that this is only the first prelim, that the weight of the first prelim is going to be relatively low, and that there are ample opportunities to compensate for any issues. Having said that, please do use those opportunities: we have an extensive schedule of office hours, so please drop by and discuss your prelim if you have any questions.

  • Oct 5: PRELIM 1. Will cover everything discussed in the course (in lectures, readings, and miniprojects) until the minute before the prelim starts. Closed book, no electronic devices allowed during the exam. Study up on deadlocks, synchronization, scheduling, threads, processes, and architectural support for OSes.
  • Sep 29: There was a typo in Q12 of MiniProject1, the typo is fixed and the zip is updated on CMS accordingly. (the forloop for popping the stack should look like: for i in range(0, depth-d+1:))
  • Sep 24: Some of you were confused about the barbershop problem as it was formulated in MP1 in Q6 and Q7, so we provided alternative versions that might be a bit easier to solve. If you solved Q6 and/or Q7 already, great, you do not need to solve or even look at the alternative versions. If you found Q6 or Q7 hard, try solving Q6ALT and/or Q7ALT. You only need to solve one of Q6 and Q6ALT. Same for Q7. Hope this helps.
  • Sep 16: Miniproject 1 has been released, it is due on Sep 29th at midnight.
  • Sep 20: The readme file for Miniproject 1 is updated with clarifications about submission and a bug is fixed in q4.py. The new zip file is uploaded in CMS.
  • Sep 14: The CS4411 Project 1 and FAQ1 project pages have been updated.
  • Sep 14: Prof. Sirer's office hours are canceled today.
  • Sep 7: 4411 group assignments have been made. If you are in 4411, please check to see if your netid is on the list. If it isn't, you must come to class on Thursday to get a partner assigned.
  • Sep 7: CS4411 Project 1 has been released on CMS.
  • Aug 31: Those of you wishing to recap old material on computer architecture can read Chapters 5.1-5.4, 8 and 7 of Computer Organization and Design: The Hardware/Software Interface by Patterson and Hennessy.
  • Aug 31: Two links to two different Python tutorials added! Check them out on the left hand side menu.
  • August 26: Welcome to the course!

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