Basic CS-Operating System [3i Infotech Placement]: Sample Questions 80 - 81 of 89

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Question 80

Operating System
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Describe in Detail

Essay▾

What is thrashing?

Explanation

Graph this Indicate Thrashing
  • Thrashing is little progress in a computer system because memory or other resources are either exhausted or limited to perform needed operations.
  • Caused in virtual memory schemes when the processor spends most of its time swapping pages- due to page faults.
  • It is caused when pages in memory refer other pages.
  • The large “working set” of active processes cannot be all accommodated in the real memory.
  • Virtual memory systems allows placing some pages on virtual memory- only bringing required page on demand into the RAM.
  • A thrashing system is either a very slow system might come to a halt.
  • Generally occurs when enough frames are not allocated to a process than are needed.

Two Ways to Prevent Thrashing

  • Instruct mid-term scheduler to swap out some of the process to recover from thrashing
  • Instructing the dispatcher not to load more processes after a threshold

Question 81

Operating System
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Write in Short

Short Answer▾

When reallocating memory if any other pointers point into the same place of memory do you have to readjust these other pointers or do they get readjusted automatically?

Explanation

  • Pointers are just variables that store a memory address in them.
  • We can have as many pointers that point to a single location in memory.
  • While reallocating memory the pointers are readjusted automatically.

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