PT2

38問 • 2年前

問題一覧

any pre-existing hardware environment, a piece of software that is designed to run within it, and any associated facilities used with it.

Computing Platform

Punch cards and machine language programming.

(1945–55) Vacuum Tubes

is an abstraction of a running program. It enables doing several things at the same time. support the ability to have (pseudo) concurrent operation

Process

an activity of some kind

Process

is something that may be stored on disk, not doing anything

Program

This rapid switching back and forth is called

Multiprogramming

All the runnable software on the computer, sometimes including the operating system, is organized into a number of

Sequential Process

a new process is created by having an existing process execute a

Process Creation

Process Termination: Which of these are voluntary?

Normal Exit, Error Exit

Process Termination: Which of these are involuntary?

Fatal Error, Killed by another process

Process States: actually using the CPU at that instant

Running

Process States: runnable; temporarily stopped to let another process run

Ready

Process States: unable to run until some external event happens

Blocked

process-structured operating system handles interrupts and scheduling.

Lowest Layer

sequential processes.

Above Layer

One entry per process. Contains important information about the process’ state. Information that must be saved when the process is switched from running to ready or blocked state so that it can be restarted later.

Process Table

Skeleton of what the lowest level of the operating system does when an interrupt occurs.

Interrupt Handling and Scheduling

CPU utilization as a function of the number of processes in memory.

Modelling of Multiprogramming

In many applications, multiple activities are going on at once. Give the ability for the parallel entities to share an address space and all of its data.

Threads

reads incoming requests for work from the network and chooses an idle (i.e., blocked) worker thread to hand the request

Dispatcher

the situation of allowing multiple threads in the same process

Multithreading

Processes frequently need to communicate with other processes: To pass information from process to another To enable proper sequencing when dependencies are present

Inter-process Communication (IPC)

Two or more processes are reading or writing some shared data and the final result depends on who runs precisely when

Race Conditions

No two processes may be simultaneously inside their critical regions.

Mutual Exclusion (mutex)

No assumptions may be made about speeds or the number of CPUs.

No Assumption

No process running outside its critical region may block other processes.

Progress

No process should have to wait forever to enter its critical region

No Starvation

the part of the program where shared variables are accessed

Critical Region

two processes strictly alternate in entering their critical regions It is not really a serious candidate as a solution because it violates condition

Strict Alternation

Classical IPC Problems: Models access to a bounded buffer. Producer won't try to add data into the buffer if it's full.

Producer Consumer Problem

Classical IPC Problems: Models processes competing for exclusive access to a limited number of resources such as I/O devices

Dining Philosophers Problem

Classical IPC Problems: Models access to a database. Two readers can read at once. A writer should not wait longer than needed.

Readers Writers Problem

What are the units of execution?

Processes

How are those units of execution represented?

Process Control Blocks (PCBs)

How are processes created?

CreateProcess (Windows), fork/exec (Unix)

How does a process move from one state to another?

Scheduling, I/O, creation, termination

What are the possible execution states of a process?

Running, ready, waiting

How is work scheduled in the CPU?

Process states, process queues, context switches

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dulsetnet · 54問 · 1年前

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