Basic process of process scheduling

This article is mainly about the basic process of process scheduling , If you want to know more about processes and threads , Please enter the entry of this article Detailed explanation of processes and threads

Catalog

1. What is a process

2. How does the operating system manage processes

3. Process scheduling process

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1. What is a process

You need to know the scheduling process of the process , First of all, we need to understand what is the process , Let's open the task manager , You will find that the first column is the process , As shown in the figure below ：

If we open one more software , You will find that there is one more column in the task manager process , This is the process corresponding to the software , We can understand that a process is a task , When closing a task , The corresponding process will end . The process in this , Some are automatically turned on by the system , Some of them we opened manually . 

2. How does the operating system manage processes

From just to task manager , We can see that there are many processes , How are they managed by the system ？

Tip1: First describe a process
We need to clearly point out the relevant attributes in the process .

for example ： To describe a student , We need students' schools , major , Names, etc .

Tip2: Organize several processes
The system will use the appropriate data structure , Store the relevant information of each process , It is convenient to add, delete, modify and check in the future .

Tip3: Let the process work properly
If a process is to work properly , We need to allocate some system resources to him , Before a process starts , The corresponding file is stored on the hard disk , When we double-click a software , In fact, the corresponding .exe Program , It will be loaded into memory , What resources do we all need ？

1. Memory （ Used for loading .exe file ）

2. Hard disk （ For operating files ）

3.CPU（ Used to execute instructions on the process ）

3. Process scheduling process

Process scheduling It only happens in multitasking operating systems , Because the single task operating system only executes one task at a time （ process ）, So there is no such thing as scheduling .

Multitasking operating system means that there are multiple processes running at every moment , So called scheduling , It's actually time management .

Suppose Zhang San is a handsome mess of beautiful men , In good shape .
This leads to Zhang San being pursued by many girls .
In principle ： At the same time , Zhang San can only talk about one girlfriend .
Zhang San hopes his future girlfriend ： Virtuous , rich 、 White and beautiful skin .（ From the perspective of real life , The author has never seen such a person ）
But the suitors around me , There is no such person .
therefore , Zhang San ( operating system ) Talk at the same time 3 A girlfriend （3 A process / Mission ）, To gather all the characteristics of the above ideal girlfriend .（ Three tasks are performed simultaneously ）
A： rich , It's too long to say
B： Virtuous ： Very intimate , Don't say more .
C： White and beautiful skin ： Beautiful as heaven , Just a little temper 、
Set the characteristics of three people , Zhang San will have a perfect experience .
But obviously unscientific , For this reason, Zhang San needs to arrange time reasonably .
Avoid the same moment , These three people meet . As long as we don't meet , It's safe .
On this premise , Zhang San can continue this state .
A real master of time management .
How to manage time ？
Make a schedule
Monday ： and A Go shopping
Tuesday ： and B Go to the library
Wednesday ： and C go to see the films
Thursday …
Everyone arranges a specific time in turn , Through such a schedule , Manage reasonably .
From a macro point of view ： Zhang San also talked about 3 A girlfriend .
From a micro point of view ： At the same time , Zhang San is just with a girlfriend .
This is concurrency ( Concurrency in a broad sense ).
So now Zhang San has passed such a timetable , Just have a good conversation with these girlfriends “ Dispatch ”.
The process of planning a timetable , That is to say “ Dispatch ” The process of .