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|
+--------------------+
| OS Development |
| PROJECT 0: INTRO |
| DESIGN DOCUMENT |
+--------------------+
---- GROUP ----
>> Fill in the names and email addresses of your group members.
Peter Ketscher <e9651415@mail.student.tuwien.ac.at>
Karoline Knoth <e0326266@student.tuwien.ac.at>
Manuel Mausz <manuel-uni@mausz.at>
---- PRELIMINARIES ----
>> If you have any preliminary comments on your submission, notes for the
>> TAs, or extra credit, please give them here.
>> Please cite any offline or online sources you consulted while
>> preparing your submission, other than the Pintos documentation, course
>> text, lecture notes, and course staff.
TODO
ALARM CLOCK
===========
---- DATA STRUCTURES ----
>> A1: Copy here the declaration of each new or changed `struct' or
>> `struct' member, global or static variable, `typedef', or
>> enumeration. Identify the purpose of each in 25 words or less.
struct thread:
int64_t wakeup_tick ...absolute tick when to wake up the thread
---- ALGORITHMS ----
>> A2: Briefly describe what happens in a call to timer_sleep(),
>> including the effects of the timer interrupt handler.
In case of a positive tick value we calculate the tick when to awake the
current thread and store that inside the per thread structure. Afterwards
we disable interrupts and insert the thread into our wakup list which is
sorted by wakeup-tick in ascending order. Finally we block the thread
and restore the interrupt value.
>> A3: What steps are taken to minimize the amount of time spent in
>> the timer interrupt handler?
We sort our alarm/wake-up list by wakeup-tick value in ascending order.
Thus we can return as soon as the first thread doesn't need to get unblocked.
---- SYNCHRONIZATION ----
>> A4: How are race conditions avoided when multiple threads call
>> timer_sleep() simultaneously?
TODO
>> A5: How are race conditions avoided when a timer interrupt occurs
>> during a call to timer_sleep()?
We've disabled the interrupts during list operations.
---- RATIONALE ----
>> A6: Why did you choose this design? In what ways is it superior to
>> another design you considered?
It's very simple, doesn't require any complex structures and memory allocations
and fulfills the needs of project0.
ARGUMENT PASSING
================
---- DATA STRUCTURES ----
>> A1: Copy here the declaration of each new or changed `struct' or
>> `struct' member, global or static variable, `typedef', or
>> enumeration. Identify the purpose of each in 25 words or less.
---- ALGORITHMS ----
>> A2: Briefly describe how you implemented argument parsing. How do
>> you arrange for the elements of argv[] to be in the right order?
>> How do you avoid overflowing the stack page?
---- RATIONALE ----
>> A3: Why does Pintos implement strtok_r() but not strtok()?
strtok() uses global data, so it is unsafe in threaded programs such as kernels.
>> A4: In Pintos, the kernel separates commands into a executable name
>> and arguments. In Unix-like systems, the shell does this
>> separation. Identify at least two advantages of the Unix approach.
SURVEY QUESTIONS
================
Answering these questions is optional, but it will help us improve the
course in future quarters. Feel free to tell us anything you
want--these questions are just to spur your thoughts. You may also
choose to respond anonymously in the course evaluations at the end of
the quarter.
>> In your opinion, was this assignment, or any one of the three problems
>> in it, too easy or too hard? Did it take too long or too little time?
>> Did you find that working on a particular part of the assignment gave
>> you greater insight into some aspect of OS design?
>> Is there some particular fact or hint we should give students in
>> future quarters to help them solve the problems? Conversely, did you
>> find any of our guidance to be misleading?
>> Do you have any suggestions for the TAs to more effectively assist
>> students, either for future quarters or the remaining projects?
>> Any other comments?
|
