Silberschatz - Operating System Concepts 9th-cap9

Silberschatz - Operating System Concepts 9th-cap9

1. Virtual Memory

   • Page sharing benefits
     • System libraries can be shared by several processes through mapping of the shared object into a virtual address space.
     • processes can share memory
     • Pages can be shared during process creation, speeding up process creation
   • Demand Paging
     • Lazy Swapper
   • copy-on-write
     • allows childs proccesses to to initially share the same pages
   • Page Replacement
     • Basic page replacement
       • 1. Find the location of the desired page on the disk
       • 2. Find a free frame
       • 3. Read the desired page into the newly freed frame; change the page and frame tables
       • 4. Continue the user process from where the page fault occurred
     • FIFO Page replacement
     • Optimal page replacement
     • LRU page replacement
     • LRU Approximation Page Replacement
     • Counting-based Page Replacement
     • Page Buffering
     • Application and page replacement
   • Allocation of frames
     • Minimum Number of Frames
     • Allocation Algorithm
     • Thrashing
   • Allocating Kernel Memory
     • Buddy system
     • Slab Allocation