Message Tube Prep Knowledge Point explaining • Operating system processes and threads

The Information System Management Engineer is an intermediate examination in the National computer Technology and software Professional Technical Qualification Examination (hereinafter referred to as the Software Qualification examination). The examination of Information System Management engineer requires examinee to master the relevant knowledge content of computer system, operating system, database, computer network, informationization and information system. The Information System Management Engineer Exam requires a wide range of content, and what are the key points to be mastered during preparation? Follow the Greek soft exam academy to learn about the information Systems Management Engineer's operating system section about the processes and threads that need to be focused.

Information Systems Management Engineer preparation for Knowledge point explaining process and thread

1. Process

(1) Process concept

A process is the process by which a program runs on a data set, which is an independent unit of the system's resource allocation and scheduling. It consists of the program block, the Process Control block (PCB) and the data block three parts.

(2) The difference and connection between process and procedure

A process is a process of execution of a procedure, without which there is no process;

A program is a set of program statements that complete a particular function, and it is always present as long as it is not destroyed;

The program is a static concept, and the process is a dynamic concept, it is created by the creation, the completion of tasks due to revocation, the process is the system for resource allocation and scheduling of independent units, and the program is not.

(3) The process of the three-state and the conversion between

three-State description

Operating state: Possession processor is running

Ready state: Refers to the operating conditions, waiting for the system to allocate the processor to run

Wait state: Also known as a blocking state or sleep state, means that there is no running condition, waiting for an event to complete

the transformation between three states

Operation State-wait state: Wait for the use of resources, such as waiting for peripheral transmission, waiting for human intervention

Wait state-ready state: Resources are met, such as peripheral transmission end, manual intervention completed

Run state--ready state: Run time slice to, appear higher priority process

Ready state-run state: Select a ready process when the CPU is idle

(4) Process Control related concepts

Process Control: It is the implementation of all processes in the system from creation to extinction of the entire process of effective control, by the operating system kernel in the primitive language;

Primitive: Refers to a number of machine instructions, used to complete a particular function of the program segment, the original language is not allowed to be split in execution, that is, atomic operations are either done, or do not do.

Sync/Mutex:

Synchronization: is a direct constraint between the process of cooperation.

Mutual exclusion: The indirect restriction between the process of applying critical resources.

Critical resource: Refers to a resource that can be used only by one process at a time.

Critical section: The procedure in which a heap critical resource is implemented in the process.

2. Threads

(1) thread two basic properties

An independent unit that can have resources, a basic unit that can be independently dispatched and assigned;

(2) thread-to-process relationship

Threads act as the basic unit of dispatch and allocation, and processes act as units for allocating resources independently.

A thread is an entity in a process.

Threads have only a few resources to run: program counters, a set of registers, stacks.

Threads can share all the resources owned by a process with other threads of the same process.

(3) thread classification

User-level threads, kernel support-level threads

Message Tube Prep Knowledge Point explaining • Operating system processes and threads