JP2872027B2 - Process switching control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process switching control method for a computer.

[0002]

2. Description of the Related Art Conventionally, this type of process switching control method is configured to execute only one process at a time in a system or a processor group having a common memory space.

FIG. 3 is a processing flowchart of an example of a conventional process switching process. According to FIG. 3, the process switching process including the rollout process is not started at all until the processor 1j that has issued the lock request succeeds later.

[0004]

In this conventional switching control method, when a certain processor attempts to start processor switching processing, another processor in the system or in a processor group having a common memory space already has the process switching. When the process has been started, there is a problem that the process is waited at the start of the process switching process until the process is completed. If this is shown in the example of FIG. 3, it can be seen that the time during which the process switching process lock bit is set becomes longer, and the probability that the lock is unsuccessful even if the processor issues a lock request increases.

[0005]

According to the present invention, there is provided a method for switching a process in an information processing apparatus comprising a plurality of processors and controlled to perform a process switching process only on a single processor at the same time. A flag that is set when the rollout process of the running process is completed and reset when the process switching process is completed, and that when any one processor attempts to start the process switching process, When a processor other than the one processor is in the process of switching the process, the processor performs a rollout process of the process being executed on the arbitrary one processor, sets the flag, and causes the processor other than the arbitrary one of the processors to switch the process. Upon completion of the processing, the arbitrary one processor Switching process is started, and if the flag is set, control is performed so that rollout processing performed during the process switching process is not performed, and the flag is reset when the process switching process ends. Process switching control method. Features.

[0006]

The process switching process includes a process selection process for selecting a process to be executed next, a roll-out process for writing back process information of a process that has been executed up to now from the processor to the memory, and a next execution process. Roll-in processing for reading process information of a process to be tried from a memory into a processor is included.

[0007] Even if another processor is executing the process switching process, the rollout process is irrelevant to the process of the process switching process and can be executed independently. The rollout process indicates around 30% of the process switching process time. Therefore, if the rollout processing is completed in advance while another processor is executing the process switching processing, the process switching processing time can be reduced by the rollout processing time.

The present invention has been made by focusing on this point.

[0009]

FIG. 2 shows an embodiment of the present invention.
In the present embodiment, the rollout processing completion flags 100 to 1n
0, a processor 10-1n, a system control device 2, a process switching process lock bit 2
It is composed of a main memory procedure 3 provided with 0.

When one of the processors 10 to 1n starts the process switching process,
It is checked whether the process switching lock bit 20 has already been set, and if not set, it is set.

If the process switching lock bit 20 has already been set, it means that another processor is executing a process switching action. In this case, the information of the process executed so far is written back to the process information area on the memory (rollout processing), and a rollout processing completion flag is set.

Thereafter, the process switching processing lock bit 20 is checked again. At this time, if the process switching process lock bit 20 is still set, the process switching process start waiting is waited, and the process switching process lock bit 20 is checked at a certain time interval, and waits for a reset state.

When the process switching lock bit 20 is checked, if it is reset, it is set.
Start the process switching process.

When the process switching process starts, a process selection process is performed, and a process to be executed next is selected.

When the process selection process is completed, the roll-out process starts. If the roll-out process completion flag is set at this time, the process proceeds to the next roll-in process without performing the roll-out process. If the rollout processing completion flag is not set, the rollout processing is performed.

When the roll-out processing is completed, the process switching processing lock bit 20 and the roll-out processing completion flag are reset, and then the roll-in processing is started.

FIG. 1 is a processing flow chart of the above embodiment. Referring to FIG. 1, after setting a process switching process lock bit (when a lock request is issued and a lock success is received), the processor 1i performs a process switching process including a process selection process, a rollout process, and a rollin process. Before the roll-out processing is completed and the roll-in processing is started, the process switching processing lock bit is reset (a lock release request is issued).

While the process switching lock bit is set, any attempt by another processor 1i to be set is unsuccessful. As soon as the other processor 1i receives the lock failure, it performs the rollout process, sets the rollout completion flag after the rollout process is completed, and issues the lock request again. The lock request is repeated until a lock success is received, and when a lock success is received, a process selection process is performed.

After the process selection processing is completed, if the rollout completion flag is set, a lock release request is issued and then the rollin processing is performed. If the rollout completion flag is not set, a rollout process is performed, and after a lock release request, a rollin process is performed.

[0020]

As described above, conventionally, when a certain processor is executing a process switching process and another processor tries to start the process switching process, the process switching process is awaited. On the other hand, in the present invention, by executing the rollout process in advance of the process switching process start waiting time, the process time after the process switching process is started can be reduced, and as a result, competition of the process switching process in the system can be reduced. Has the effect of reducing.

[Brief description of the drawings]

FIG. 1 is a processing flowchart of an embodiment of the present invention.

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is a flowchart of a conventional process switching process.

[Explanation of symbols]

 10 to 1n processor 100 to 1n0 rollout process completion flag 2 system control device 20 process switching process lock bit 3 main storage device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 15/16 430 G06F 9/46 360 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A process switching method in an information processing apparatus comprising a plurality of processors and controlled to perform a process switching process only on a single processor at the same time. A flag that is set when the process is completed and is reset when the process switching process is completed is provided. When any one processor attempts to start the process switching process, a processor other than the arbitrary one processor is performing the process switching process. In the case of (1), when the process executed on the arbitrary one processor is rolled out, the flag is set, and when a processor other than the arbitrary one processor finishes the process switching process, the arbitrary one processor is processed. Starts the process switching process, and A process switching control method that controls not to perform a rollout process performed during the process switching process if the flag is set, and resets the flag when the process switching process ends. 2. The process switching method according to claim 1, wherein the plurality of processors share a single main memory.