Basic CS-Operating System [Redpine Infotech Placement]: Sample Questions 2 - 3 of 4

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Question 2

Operating System

Question

MCQ▾

What are the different types of IPC mechanisms?

Choices

Choice (4)

a.

Indirect communication (mailbox)

b.

Synchronous/Asynchronous communication (Naming.) .

c.

Context switching

d.

Direct communication (messages)

Answer

d.

Explanation

  • IPC mechanisms are a set of programming interfaces that allow a programmer to coordinate activities among different program processes or threads.
  • Threads can run concurrently in an operating system.
  • For example, they allow a program to handle many user requests at the same time each with different thread.
  • Direct communication is an IPC mechanism.
  • Each process that wants to communicate must name the recipient or sender of the communication.
  • Send and receive primitives are defined as bellow:
    • Send (P, message) - send a message to process P.
    • Receive (Q, message) - Receive a message from process Q.

Question 3

Operating System
Edit

Describe in Detail

Essay▾

Specify any 3 items related to the context of process?

a. Process state.

b. Process Attribute.

c. Accounting Information.

d. PCB (Process control Block)

e. Advantages and disadvantages of cache buffer?

f. Increasing memory- many page faults occur?

Explanation

Process State

  • Process state is the state field in the process descriptor.
  • A process descriptor is a task_struct-type data structure with fields containing all of the information about a single process.
  • Also referred to as a task, process is an instance of a program in execution.
  • The state field in the process descriptor describes what is currently happening to a process.
  • Each process has an execution state, which indicates what it is currently doing
    • Ready: waiting to be assigned to CPU
      • Could run, but another process has the CPU
    • Running: executing on the CPU
      • Process currently controls the CPU
    • Waiting: waiting for event
      • Cannot make progress until event.

PCB

  • A data structure in the operating system kernel containing the information needed to manage a particular process.
  • Used for storing the collection of information about the processes.
  • This information is used by the CPU at the run time.
  • Below information is stored into PCB
    • Name of the process.
    • State of the process- ready, active, wait.
    • Resources allocated to the process
    • Memory provided to the process.
    • Scheduling information.
    • Input and output devices used by the process.

Advantages and Disadvantages of Cache Buffer

Cache buffer is used to cache the data read or written to the disk

Advantages:

  • Use of buffer allows uniform disk access.
  • Makes it simple to design system.
  • Provides fast access
  • Promotes good compression performance

Disadvantages:

  • System now has longer memory access time
  • Requires inverted page table
  • Use of the buffer cache requires an extra data copy when reading and writing to and from user processes.
  • Suffers from internal fragmentation

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