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OS · written course

What the machine is doing while your program runs

What the machine is really doing while your program runs.

Start reading32 pages · about 170 minutes

By the end of this course

Your program thinks it owns the computer. It does not: it owns a convincing illusion, built by software that decides when it runs, what memory it can see, and what happens when it asks for a file. By the end you can read a scheduling table, compute a page fault rate, spot a deadlock and explain why your laptop slows to a crawl when memory runs out.

All 32 pages

  1. 1Eight programs, four cores, no waiting5 min read
  2. 2From power on to a login prompt5 min read
  3. 3The instruction your program is not allowed to run5 min read
  4. 4How a program asks for something it cannot do5 min read
  5. 5What a process actually is5 min read
  6. 6Running, waiting, and the cost of swapping5 min read
  7. 7Where a new process comes from5 min read
  8. 8Threads, and the shared memory that bites5 min read
  9. 9Choosing between the two5 min read
  10. 10Talking across the boundary5 min read
  11. 11When two threads touch the same thing5 min read
  12. 12Mutexes, semaphores and the bathroom key5 min read
  13. 13Three tools that look alike5 min read
  14. 14Three problems worth knowing by name6 min read
  15. 15Two threads, two locks, no progress6 min read
  16. 16Four ways to deal with it5 min read
  17. 17Deciding who runs next6 min read
  18. 18Deciding who runs next6 min read
  19. 19When late is the same as wrong5 min read
  20. 20Fitting programs into memory5 min read
  21. 21Finding room for a program5 min read
  22. 22Dividing memory by meaning5 min read
  23. 23Paging: memory that is not contiguous6 min read
  24. 24Running a program bigger than your RAM6 min read
  25. 25Choosing what to evict6 min read
  26. 26When the machine stops doing work5 min read
  27. 27How a folder tree is stored on a flat disk5 min read
  28. 28How a file is actually stored6 min read
  29. 29The order requests reach the disk5 min read
  30. 30Why the disk is the slowest thing you own5 min read
  31. 31Many systems on one machine6 min read
  32. 32Who is allowed to do what6 min read

Then what

Reading is the first half. When you finish, the questions for this subject test whether it went in, and every wrong option tells you why it was wrong rather than just that it was.

See the questions for OS