Chapter 3 OS Processes

A process is a program in execution.

A program is a passive executable stored on disk while a process is an active program running in memory.

Text section, data section, heap, stack, program counter, and CPU registers.

Executable program instructions.

Global and static variables.

Local variables, function parameters, and return addresses.

Dynamically allocated memory.

Memory allocated during program execution using functions such as malloc().

The heap.

The address of the next instruction to execute.

To store temporary execution data and intermediate values.

New, Ready, Running, Waiting, and Terminated.

The process is being created.

The process is waiting to be assigned to the CPU.

The CPU is currently executing the process.

The process is waiting for an event such as I/O completion.

The process has finished execution.

A data structure used by the operating system to store information about a process.

Process state, program counter, CPU registers, scheduling information, memory information, accounting information, and I/O information.

It allows the operating system to pause and later resume a process.

The smallest unit of CPU execution within a process.

Code section, heap, and data section.

Stack, program counter, and CPU registers.

The operating system selecting which process receives CPU time.

To maximize CPU utilization and system responsiveness.

The set of processes waiting for CPU execution.

The set of processes waiting for an event such as I/O completion.

The CPU switching from one process to another.

The old process state is saved and the new process state is loaded.

In the Process Control Block.

Because no useful work is performed while switching processes.

Operating system complexity, PCB complexity, and hardware support.

A process that creates one or more child processes.

A process created by another process.

fork().

0.

The PID of the child process.

-1.

exec().

wait().

exit().

abort().

A terminated child process whose parent has not called wait().

A child process whose parent terminated before it did.

When termination of a parent process causes all child processes to terminate.

A mechanism that allows processes to communicate and synchronize.

Information sharing, computation speedup, modularity, and convenience.

Shared memory and message passing.

A memory region shared between processes for communication.

The user processes.

Synchronization.

Processes communicating by sending and receiving messages.

send(message) and receive(message).

Processes explicitly name each other when sending messages.

Processes communicate through mailboxes or ports.

A shared communication object used for indirect communication.

Communication where the sender or receiver waits.

Communication where execution continues immediately.

When both send and receive operations are blocking.

The queue of messages attached to a communication link.

No messages are queued and sender and receiver must synchronize.

The communication link holds a limited number of messages.

The communication link can hold unlimited messages.

A synchronization problem where one process produces data and another consumes it.

A buffer with no practical size limit.

A buffer with a fixed maximum size.

A communication channel between two processes.

A unidirectional pipe that typically requires a parent-child relationship.

Anonymous pipes.

A bidirectional pipe that does not require a parent-child relationship.

An endpoint for communication.

An IP address and a port number.

127.0.0.1.

A mechanism that allows a process to call a procedure on another machine as if it were local.

A proxy on the client side that marshals parameters and contacts the server.

A proxy on the server side that unpacks parameters and executes the procedure.

task_struct.

PID, process state, parent process, children, open files, and memory information.