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Questions and Answers
What is the term used for a program that is currently executing and has progress in a sequential manner?
What is the term used for a program that is currently executing and has progress in a sequential manner?
Which of the following states indicates that a process is waiting for an event to occur?
Which of the following states indicates that a process is waiting for an event to occur?
Which of these is NOT part of a Process Control Block (PCB)?
Which of these is NOT part of a Process Control Block (PCB)?
What information does a Process Control Block not provide?
What information does a Process Control Block not provide?
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Which queue consists of all processes that are currently ready and waiting to execute?
Which queue consists of all processes that are currently ready and waiting to execute?
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Which state represents a process that has completed its execution?
Which state represents a process that has completed its execution?
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What is the purpose of process migration between various queues?
What is the purpose of process migration between various queues?
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Which of the following is an example of a device queue?
Which of the following is an example of a device queue?
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Where is a process placed when it issues an I/O request?
Where is a process placed when it issues an I/O request?
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What does the long-term scheduler primarily control?
What does the long-term scheduler primarily control?
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What is the role of a medium-term scheduler?
What is the role of a medium-term scheduler?
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Which scheduler is invoked most frequently to manage process execution?
Which scheduler is invoked most frequently to manage process execution?
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What is required for P and Q to communicate effectively?
What is required for P and Q to communicate effectively?
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In direct communication, which process is needed to send a message?
In direct communication, which process is needed to send a message?
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What happens during a context switch?
What happens during a context switch?
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What characterizes an I/O-bound process?
What characterizes an I/O-bound process?
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How many links exist between each pair of communicating processes?
How many links exist between each pair of communicating processes?
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Which statement best describes a communication link?
Which statement best describes a communication link?
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What does the term 'process creation' refer to?
What does the term 'process creation' refer to?
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Which scheduler would be the slowest in terms of invocation frequency?
Which scheduler would be the slowest in terms of invocation frequency?
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What characteristic describes the recipient in an asymmetric addressing scheme?
What characteristic describes the recipient in an asymmetric addressing scheme?
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What is a key characteristic of the resources shared between a parent process and its child processes?
What is a key characteristic of the resources shared between a parent process and its child processes?
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What does the fork system call do in UNIX?
What does the fork system call do in UNIX?
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Under what condition may a parent process terminate its child processes!
Under what condition may a parent process terminate its child processes!
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What distinguishes cooperating processes from independent processes?
What distinguishes cooperating processes from independent processes?
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What is the primary function of the receive operation in Interprocess Communication (IPC)?
What is the primary function of the receive operation in Interprocess Communication (IPC)?
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Which of the following describes the bounded-buffer scenario in the producer-consumer problem?
Which of the following describes the bounded-buffer scenario in the producer-consumer problem?
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Which of the following is a primary reason for providing an environment supporting process cooperation?
Which of the following is a primary reason for providing an environment supporting process cooperation?
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What happens when a process executes its last statement and requests the operating system to terminate it?
What happens when a process executes its last statement and requests the operating system to terminate it?
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What is required for processes to communicate using indirect communication?
What is required for processes to communicate using indirect communication?
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Which of the following describes a property of a communication link?
Which of the following describes a property of a communication link?
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What operation is NOT included in the indirect communication model?
What operation is NOT included in the indirect communication model?
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In which scenario might a blocking send operation occur?
In which scenario might a blocking send operation occur?
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Which type of message passing is considered asynchronous?
Which type of message passing is considered asynchronous?
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What describes a zero capacity buffering system?
What describes a zero capacity buffering system?
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Which statement about mailbox sharing is true?
Which statement about mailbox sharing is true?
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Which is NOT a primitive operation in indirect communication?
Which is NOT a primitive operation in indirect communication?
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Study Notes
Process Concept
- Operating systems execute various programs, categorized as batch systems for jobs and time-shared systems for user tasks.
- A process is a program in execution, progressing sequentially and comprising a program counter, stack, and data section.
Process State
- Process states include:
- New: process being created.
- Running: instructions are being executed.
- Waiting: process waiting for an event or resources.
- Ready: process waiting to be assigned to a CPU.
- Terminated: process execution completed.
Process Control Block (PCB)
- PCB is a data structure representing a process in memory, storing various information including:
- Current process state
- Program counter
- CPU registers
- Scheduling information
- Memory management data
- Accounting info
- I/O status data
Process Scheduling Queues
- Job queue: contains all processes in the system.
- Ready queue: contains processes ready for execution in main memory.
- Device queues: contains processes awaiting I/O devices.
Schedulers
- Long-term scheduler: selects processes for the ready queue from the job queue; invoked infrequently.
- Short-term scheduler: selects the next process to be executed; invoked very frequently.
- Medium-term scheduler (MTS): handles process swapping in and out of memory for better performance.
Context Switch
- A context switch occurs when the CPU switches to a different process, requiring the saving of the old process's state and loading of the new one.
- Context-switch time introduces overhead, as the system does not perform useful work during the switch.
Process Creation
- Parent processes create child processes, forming a process tree, with each child having one parent.
- Resources may be shared between processes, but address spaces are separate, preventing changes in one from affecting the other.
-
UNIX example:
fork
system call creates a new process;exec
replaces the child's memory with a new program.
Process Termination
- A process terminates when it executes its last statement and requests termination, leading to resource deallocation and removal from system lists.
- Parents may also terminate child processes under specific conditions, leading to cascading termination in some operating systems.
Cooperating Processes
- Independent processes operate without affecting each other, while cooperating processes can influence one another for purposes such as:
- Information sharing
- Speed-up in computation
- Modularity
- Convenience of programming
Producer-Consumer Problem
- Involves cooperating processes where a producer creates information consumed by a consumer.
- Unbounded-buffer: has no limit on buffer size, allowing producers to process without waiting.
- Bounded-buffer: has a fixed size, requiring producers to wait if the buffer is full.
Interprocess Communication (IPC)
- IPC mechanisms enable processes to communicate and synchronize actions, primarily through message passing.
- Operations include
send(message)
andreceive(message)
involving either fixed or variable length messages. - Establishes communication links, which can be physical or logical.
Direct Communication
- Requires processes to name each other explicitly for message exchange:
-
send(P, message)
sends a message to process P. -
receive(Q, message)
receives a message from process Q.
-
Indirect Communication
- Involves mailboxes (or ports) for message exchange, characterized by:
- Unique identifiers for mailboxes.
- Permitting communication only between processes sharing a mailbox.
- Links may be unidirectional or bi-directional.
Buffering
- Message queuing can be implemented with:
- Zero capacity: sender waits for receiver.
- Bounded capacity: finite queue length; sender waits if full.
- Unbounded capacity: infinite length; sender never waits.
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Description
Explore the key concepts of processes in operating systems through this quiz. You'll learn about process scheduling, interprocess communication, and the differences between batch and time-shared systems. Test your knowledge on the important aspects of processes and their management.