Computer Science 432 Operating Systems Williams College Fall 2006

Agenda

• Announcements
  • Sigma Xi talks. Be there if you can.
• Labs 3 and 4 back
• Shell lab discussion
• Lecture assignment recap
• Deadlock
  • Deadlock avoidance
    • augmented resource allocation graphs
    • Banker's Algorithm
  • Detection and recovery
• Memory Management
  • Binding time
    • Programming or compile time
    • Load time
    • Execution time
  • Logical vs. Physical Address Space
  • Memory protection
  • Swapping
  • Contiguous allocation
    • Processes are loaded into available chunks
    • Hardware support: base/limit registers
    • Allocation algorithms:
      • first-fit
      • best-fit
      • worst-fit
  • Fragmentation
    • external fragmentation
    • internal fragmentation
  • Paging
    • break memory into fixed-sized chunks - the "page size"
    • logical memory chunks are pages
    • physical memory chunks are frames
    • can create virtual memory - larger than available physical memory
    • manage with a page table to translate logical to physical addresses
    • logical addresses consist of a page number+page offset
    • paging requires two memory accesses per logical access
    • help reduce this with a translation lookaside buffer (TLB)
    • why can we get away with this? Locality!

Lecture Assignment

Due at the start of class, Tuesday, October 31.

Turn in short answers to these questions. Please turn in a hard copy (typeset or handwritten are OK). We will discuss these questions during class, so no late submissions are accepted.

SG&G 7.11, 8.3

The readings for next time are SG&G Chapter 9.