Shulou(Shulou.com)06/01 Report--

Change (a process will go through several different forms). The daily process has the following five forms, and the first three are the fundamental forms of the process.

1) running mode: the process is running on the disposal machine. In the case of a single processor, at most one process is in operation at a time.

2) stop form: the process has been in the form of preparatory operation, that is, the process has obtained all the necessary capital except the disposal machine, and it can run once the disposal machine is lost.

3) congestion pattern, also known as waiting pattern: the process is waiting for something to stop running, such as waiting for some capital to be available (excluding the disposal machine) or waiting for the output / input to be completed. Even if the disposal machine is idle, the process will not work.

4) Creative form: the process is being created and has not yet been transferred to a proper form. The creation process usually requires multiple steps: first, request a blank PCB, and fill in some information to master and govern the process to the PCB; then allocate the necessary capital for the operation of the process in bits and pieces; initially transfer the process to a proper form.

5) completion form: the process is disappearing from the bits and pieces, which can be the normal completion of the process or other reasons for the suffix to join the operation. When the process requirements are completed and run, piecemeal start must set the process as the completed form, and then further deal with the tasks such as capital release and reception.

Pay attention to the difference between the stop form and the waiting form: the stop form means that the process only needs a short disposal machine and can be performed immediately as long as the disposal machine capital is obtained, while the waiting form refers to the process requiring other capital (in addition to the disposal machine) or waiting for something. The reason for delimiting the disposal machine and other capital is that in the time-sharing piecemeal film wheel color system, each process is allocated several milliseconds. In other words, the time for the process to lose the disposal machine is very short and very frequent, and the process is frequently converted to a proper form in practice; while the use and allocation of other capital (such as peripherals) or the occurrence of something (such as the completion of IUnip O operation) is absolutely long, and the number of times the process changes to the waiting form is absolutely less. From this point of view, the stop form and the waiting form are two completely different forms in the process life cycle, which obviously need to be distinguished.

Figure 2-1 illustrates the transformation of the five process forms, and the transformation between the three fundamental forms is as follows:

Figure 2-1 Transformation of five process forms

Proper form-> running form: after the process of being in the proper form is adjusted, the disposal machine capital is obtained (the allocation and disposal of the machine worker piece), and the process is changed from the disorderly form to the running form.

Operation form-> stop form: the process in the running form has to give up the disposal machine after the use of the worker film, so that the process changes from the running form to the proper form. In addition, in the disposable operation bits and pieces, when there is a higher priority process, the adjustment level transforms the process being performed into an appropriate form, allowing the higher priority process to be performed.

Operation pattern-> congestion pattern: when a process pleads for the use and dispatch of a certain capital (such as peripherals) or waits for something to happen (such as the completion of the Icano operation), it changes from a running form to a congested form. The process asks for the service of operating piecemeal supply in the form of piecemeal misappropriation, which is a special way for operating fragmentary kernel processes to be misappropriated by running user-mode programs.

Congestion pattern-> stop pattern: when something waiting for the process arrives, such as when the operation or infix is completed, the infix disposal program must change the form of the response process from the congestion form to the stop form.

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