Historical Perspective

OS in structure way

• pros:
  • easy to develop and debug
  • Increased protection (information hiding between layers)
• cons:
  • hard to define the layers
  • circular dependency
  • low performance
  • less flexibility
  • Difficult to divide system layers

processes communication

• Shared memory

  • pros
    • efficient
    • easy to program
  • cons
    • fault intolerant (because one process may corrupt the shared data)
    • Race condition (the output is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when events do not happen in the order the programmer intended. The term originates with the idea of two signals racing each other to influence the output first)

• Message passing

  • pros
    • Scalable
    • Safer
  • cons
    • Message copy overhead

Memory Management

• logical address/virtual address: An address generated by the CPU
• physical address: the one loaded into the memory-address register of the memory
• logical address space: The set of all logical addresses generated by a program.
• physical address space: The set of all physical addresses corresponding to these logical addresses