Square6 small piece of code stub used to locate the

Info icon This preview shows pages 9–17. Sign up to view the full content.

square6 Small piece of code, stub , used to locate the appropriate memory-resident library routine. square6 Stub replaces itself with the address of the routine, and executes the routine. square6 Operating system needed to check if routine is in processes’ memory address. square6 Dynamic linking is particularly useful for libraries.
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Silberschatz, Galvin and Gagne 2002 9.10 Operating System Concepts Overlays square6 Keep in memory only those instructions and data that are needed at any given time. square6 Needed when process is larger than amount of memory allocated to it. square6 Implemented by user, no special support needed from operating system, programming design of overlay structure is complex
Image of page 10
Silberschatz, Galvin and Gagne 2002 9.11 Operating System Concepts Overlays for a Two-Pass Assembler
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Silberschatz, Galvin and Gagne 2002 9.12 Operating System Concepts Swapping square6 A process can be swapped temporarily out of memory to a backing store , and then brought back into memory for continued execution. square6 Backing store – fast disk large enough to accommodate copies of all memory images for all users; must provide direct access to these memory images. square6 Roll out, roll in – swapping variant used for priority-based scheduling algorithms; lower-priority process is swapped out so higher-priority process can be loaded and executed. square6 Major part of swap time is transfer time; total transfer time is directly proportional to the amount of memory swapped. square6 Modified versions of swapping are found on many systems, i.e., UNIX, Linux, and Windows.
Image of page 12
Silberschatz, Galvin and Gagne 2002 9.13 Operating System Concepts Schematic View of Swapping
Image of page 13

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Silberschatz, Galvin and Gagne 2002 9.14 Operating System Concepts Contiguous Allocation square6 Main memory usually into two partitions: handptright Resident operating system, usually held in low memory with interrupt vector. handptright User processes then held in high memory. square6 Single-partition allocation handptright Relocation-register scheme used to protect user processes from each other, and from changing operating-system code and data. handptright Relocation register contains value of smallest physical address; limit register contains range of logical addresses – each logical address must be less than the limit register.
Image of page 14
Silberschatz, Galvin and Gagne 2002 9.15 Operating System Concepts Hardware Support for Relocation and Limit Registers
Image of page 15

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Silberschatz, Galvin and Gagne 2002 9.16 Operating System Concepts Contiguous Allocation (Cont.) square6 Multiple-partition allocation handptright Hole – block of available memory; holes of various size are scattered throughout memory. handptright When a process arrives, it is allocated memory from a hole large enough to accommodate it.
Image of page 16
Image of page 17
This is the end of the preview. Sign up to access the rest of the document.
  • Spring '12
  • kavitha
  • Virtual memory, Gagne, Galvin

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern