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Chapter 15 I/O SCHEDULING. Quiz Question 15.1. Incorrect answer validation.


There is no right answer for Question 15.1 .
If I choose A answer then system responds that correct answers B, C.
If I choose B,C answers then system responds that correct answers A.

Isn't it funny though?

I can attach screenshot if it's needed.

Best Answers

  • fcioanca
    fcioanca Posts: 1,931
    Answer ✓

    Hi @DamirRakhimov

    The question specifies to select all correct answers, and there are multiple. If you select all the correct answers, the system will fully validate your answer. If your answer is only partially correct, it will actually show you what the remaining correct answers are. As it is currently set up, question 15.1 is correct.


  • coop
    coop Posts: 915
    Answer ✓

    Actually the question is defective as current kernels no longer even have CFQ and have BFQ etc. (on my system the correct answers were A,C,D and the only one "wrong" was "elevator" at the time this question was composed.
    We will have to review not only the question but the text to make sure what it is saying is up to date. So thanks for being vigilant.

    Please note that I/O scheduling has become less important in many scenarios due to the emerge of newer technologies for storage and we need to update to keep up with that.


  • DamirRakhimov

    @coop Thanks for detailed comment on this.

  • coop
    coop Posts: 915
    edited October 2021

    Sorry it took me a while to verify all this. It depends on distribution but the most recent kernels have dropped cfq in favor of mq-deadline, kyber, bfq and none. We need to change the answer to accept only those, so we will take mq-deadline, bfq and none as they are shown in the lecture text correctly.

    the demo video is showing its age as it was done on RHEL 7. While everything it shows is fine, the choices are the older ones including cfq. At some future date we should redo the video but it is only the very last part that is dated so it will wait for a more major course update probably.



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