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CS 5204 Operating Systems Lecture 11

CS 5204 Operating Systems Lecture 11. Godmar Back. Announcements. Last week: milestone meetings Submit revisions where indicated before MS2 Switched presentations – see reading list. Plan for Today. Midterm Brief overview of kernel systems research in 1980-2000

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CS 5204 Operating Systems Lecture 11

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  1. CS 5204Operating SystemsLecture 11 Godmar Back

  2. Announcements • Last week: milestone meetings • Submit revisions where indicated before MS2 • Switched presentations – see reading list CS 5204 Fall 2005

  3. Plan for Today • Midterm • Brief overview of kernel systems research in 1980-2000 • Create context for Exokernel/SPIN CS 5204 Fall 2005

  4. Problem Review • Problem 1: Lauer & Needham • Problem 3: VTRR: {SA=10, SB=5, SC=2, SD=1} • A B C C A B A B C A B A B A B A B B • A B C D A B A C B A B A A A B A A A • A B C D A B A B C A B A A A B A A A • Problem 4: • Write-through vs. write-back • False sharing for multiple file lease CS 5204 Fall 2005

  5. C0 C1 C2 Problem 2: Capriccio Initial checkpoint (for consistency with Figure 5, not required for credit) main S=8+ Back edge – requires checkpoint MaxPath=4096 requires this checkpoint since path main  g  s has length 8508+3 > 4096 g S=500+ s S=8000+ r S= random S= Not required for full credit – could assume random() is inlined CS 5204 Fall 2005

  6. A (somewhat selective) History of OS/Kernels • 70s: Unix (AT&T and BSD) • Plus many architecture-specific OSes • 80s: Mach (followed Accent) • Pioneered microkernel idea • 90s: • Tanenbaum vs Torvalds debate • Engineering of Windows NT & contemporary Unixes • In Parallel: decade of “Extensible OS” Research • 00s: • Virtual machine monitors • Virtual machines CS 5204 Fall 2005

  7. Cheriton 1994 The Red Line • Separates user mode & kernel mode • Q: what should go above the red line, and what should stay below CS 5204 Fall 2005

  8. Microkernels Source: Tanenbaum Distributed Systems… CS 5204 Fall 2005

  9. Microkernels (II) • Idea of “OS personality” • Provided on top using servers • Noteworthy projects: • L4 microkernel [L4] • Focus on making message-passing fast • Fluke • Industry: • NT, OSX – started with -Kernel approach, moved away – mostly for performance reasons CS 5204 Fall 2005

  10. The Torvalds/Tanenbaum Debate • Should you develop a new OS as a monolithic kernel in 1992? • Questions [Torvalds/Tanenbaum] • Microkernel vs. monolithic • How important is OS structure? • Portability • What defines portability? • Free Software • How important is the development process? CS 5204 Fall 2005

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