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1.14 - assembly line

2022-07-05 06:10:00 【It's Li sticky duck】

Catalog

One 、 The concept of pipeline

Two 、 Pipeline workflow

3、 ... and 、 No pipeline is used to execute instructions

1、 Execution process

2、 Conclusion

Four 、 Use pipeline to execute instructions

1、 Execution process

2、 Conclusion

5、 ... and 、 pipeline cycle

6、 ... and 、 Pipeline calculation formula

7、 ... and 、 Throughput of the pipeline

8、 ... and 、 Test method 1： Pipeline related calculation

One 、 The concept of pipeline

The so-called assembly line , It refers to the execution of the program , Multiple instructions overlap A quasi parallel processing implementation technology .

Two 、 Pipeline workflow

When an instruction is executed , It can usually be divided into several stages , Each stage is realized by different components ;
Divide into 3 Take the first stage as an example ： Fingering 、 analysis 、 perform ;

Fingering ： Realized by the finger taking part , Responsible for fetching instructions from memory CPU in ;

analysis ： The analysis instruction is carried out by the analysis part ;

perform ： Implemented by the execution part , Be responsible for decoding instructions , Execution instruction ;

3、 ... and 、 No pipeline is used to execute instructions

1、 Execution process

When the assembly line is not used , When the fetching part of the first instruction fetches , The analysis part and the execution part are idle ;
When the finger picking part is finished , The analysis part starts the analysis instruction , At this time, the referring part and the executing part are idle ;
When the execution of the analysis part is completed , The execution part executes instructions after compilation , At this time, the finger taking part and the analysis part are idle ;

2、 Conclusion

Thus we can see that , When instructions are executed without pipeline , Take the finger part , Analyze components , The utilization of execution parts is not high ;

Four 、 Use pipeline to execute instructions

1、 Execution process

When the first instruction starts to execute , Take the finger part and start working , Analysis part and execution part are idle ;
When the first instruction fetch is completed , The analysis part starts to work ; At this time, the finger taking part is idle , At this point, you can get the second instruction ;
When the first instruction analysis is completed , The execution part starts working ; At this time, the analysis unit is idle , At this point, you can analyze the second instruction just taken ; And since the second instruction fetching is completed , So at this time, the finger taking part is free again , So now you can get the third instruction ;

2、 Conclusion

thus it can be seen , Use pipeline to execute instructions , It can effectively improve the utilization rate of components , It effectively improves the execution efficiency of instructions ;

5、 ... and 、 pipeline cycle

At each stage of the instruction , The time of this stage with the longest execution time , Is the cycle of the assembly line ;

analysis ：
（1） For example, the workers on the assembly line , Three people work together to complete an item ; The first person needs 2 second , The second person needs 4 second , The third person needs 1 second ;
（2） If the period for completing this item is set as 1 second , So first 、 The second person can't finish his work ;
（3） Only set the period as 4 seconds , These three talents can complete their own work ;
（4） So we will generally Complete an item The time of the phase that takes the longest to execute , Set as cycle , The period in the example is 4 second ;

6、 ... and 、 Pipeline calculation formula

Time required for a single instruction +（n-1）*（ pipeline cycle ）

（1） It can be seen from the picture that , When executing the first instruction , need 3 Stages ;
（2） At the end of the first instruction , The second order zh The analysis phase has been completed , Only one execution stage is needed to complete the execution of the second instruction ;
（3） When the execution of the second instruction is completed , The third instruction has finished the analysis stage , Only one execution stage is needed to complete the execution of the third instruction ;
（4） So execute n Instruction time , Just use the time of a single instruction （ The sum of the three phases of the first instruction ）+（n-1） The time required to execute an instruction ;