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Mac OS X Panther Operating System

Mac OS X Panther Operating System. Tomomi Kotera CS 550 Section 3 Fall 2003. Presentation Overview. Overview of Mac OS X System Architecture Key technologies CPU scheduling Symmetric Multiprocessing Memory Management Conclusion. Overview of Mac OS X.

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Mac OS X Panther Operating System

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  1. Mac OS X PantherOperating System Tomomi Kotera CS 550 Section 3 Fall 2003

  2. Presentation Overview • Overview of Mac OS X • System Architecture • Key technologies • CPU scheduling • Symmetric Multiprocessing • Memory Management • Conclusion

  3. Overview of Mac OS X • UNIX-based Operating System with the intuitive user interface called Aqua • “Classic” Mac OS vs. Newer Mac OS • Four major successes of Mac OS X • Preemptive Multitasking • Symmetric Multiprocessing • Memory Protection • Virtual Memory

  4. System Architecture • Four layers of system software • Application Environments • Application Services • Core Services • Kernel Environments

  5. Preemptive Multiprocessing • Cooperative multitasking (Classic Mac OS) vs. Preemptive Multiprocessing (Mac OS X) • Preemptive Multiprocessing • Multilevel Feedback Queue Scheduling Algorithm • Round Robin Scheduling Algorithm

  6. Preemptive Multiprocessing (cont.) • Multilevel Feedback Queue Scheduling Algorithm • 128 priority levels are divided into four bands • Normal (0-51) • System High Priority (52-79) • Kernel Mode Only (80-95) • Real-Time Threads (96-127) • Real-Time Threads are treated differently • Avoid Starvation • Threads migrate within a given band

  7. Symmetric Multiprocessing • Dual processor capabilities • Share Memory and I/O bus • Kernel can execute on any processor

  8. Crush Resistant Processes are isolated in own memory spaces Cannot interfere one another If one applications crashes, the system, and other applications are unaffected - no restarts Memory Protection

  9. Virtual Memory • Classic Mac OS uses Segmentation • Mac OS X adopts Demand Paging • Large, sparse virtual address spaces • Mapping a page reference to a physical address pager application Address space Function call Page fault resume

  10. Virtual Memory (cont.) • VM Object (Virtual Memory Object) • Object-oriented nature of Mach • Contiguous repository for data indexed by byte • All data in an address space is provided through VM objects • Track and manage the resident and nonresident pages • Memory Sharing • Inheritance (shared, copy, none) • Copy-on-Write

  11. Virtual Memory (cont.) • Content of a VM object

  12. Virtual Memory (cont.) • Second-chance first in, first out (FIFO) Algorithm • Three lists of physical memory pages

  13. Virtual Memory (cont.) • Continuously check the free list • When the number of pages in the free list dips below this threshold, remove pages from the inactive list to place them on the free list • Always maintains a few pages on the inactive list • Once the free list size exceeds the target threshold, the pager rests • FIFO-like page replacement • The inactive list serves as a second chance

  14. Conclusion • Technical Success of Mac OS X • Marriage of stability, reliability and security of UNIX, with the ease of use of the Macintosh GUI • Benefits from UNIX features • Preemptive Scheduling • Symmetric Multiprocessing • Memory Management • Target both home users and IT professionals

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