JPH07182296A - Method for controlling process switching - Google Patents

Abstract

PURPOSE:To shorten processing time required after starting process switching processing by executing roll-out processing prior to the switching processing during the waiting time of start of the switching processing. CONSTITUTION:A process switching lock bit 20 is checked, and when the bit 20 is reset, the bit 20 is set up and process switching processing is started. When the switching processing is started, process selecting processing is executed to select a process to be executed next. Roll-out processing is started after the end of the selecting processing, but when a roll-out processing completion flag is set up, succeeding roll-in processing is started without executing the roll-out processing. When the completion flag is not set up, the roll-out processing is executed. At the end of the roll-out processing, the lock bit 20 and the roll-out processing completion flag are set up and then roll-in processing is started.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, this type of process switching control method has a configuration in which only one process switching control method is simultaneously executed in a system or a processor group having a common memory space.

FIG. 3 is a processing flow chart of an example of conventional process switching processing. According to FIG. 3, the process switching process including the roll-out process is not started at all until the processor 1j that has issued the lock request succeeds.

[0004]

According to this conventional switching control method, when a processor attempts to start a processor switching process, another processor in the system or a processor group having a common memory space has already switched the process. If the process has been started, there is a problem that the process is kept waiting until the process switching process starts. 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 long, and even if the processor issues a lock request, the probability of lock failure becomes high.

[0005]

According to the method of the present invention, each processor is provided in a process switching system in an information processing apparatus which is controlled to perform a process switching process only on a single processor at the same time. Is provided with a flag which is set at the end of the rollout processing of the process being executed and reset at the end of the process switching processing, and when any one processor tries to start the process switching processing, When a processor other than the one processor is in the process switching process, the process being executed on the arbitrary one processor is rolled out, the flag is set, and the processor other than the arbitrary one processor switches the process. When the processing is completed, the arbitrary one processor When the replacement process is started and the flag is set, the rollout process performed during the process switching process is controlled not to be performed, and the flag is reset when the process switching process is completed. Process switching control method. Characterize.

[0006]

[Function] The process switching process includes a process selecting process for selecting a process to be executed next, a rollout process for writing the process information of the process that has been executed up to now into the memory from the processor, and a next process executing process. It can be divided into roll-in processing to read the process information of the process to be read from the memory into the processor.

By the way, the roll-out process is independent of the process to be subjected to the process switching process even when another processor is executing the process switching process, and can be executed independently. The rollout process represents around 30% of the process switching process time. Therefore, the process switching processing time can be shortened by the rollout processing time if the rollout processing is completed before another processor is executing the process switching processing.

The present invention has been made in view of this point.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 2, which illustrates an embodiment of the present invention,
In this embodiment, the rollout process completion flags 100 to 1n
0 to each of the processors 10 to 1n, the system control device 2, and the process switching process lock bit 2
It is composed of the main memory procedure 3 provided with 0.

When one of the processors 10 to 1n is about to start the process switching process,
The process switching lock bit 20 is checked to see if it is already set, and if not set, it is set.

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

Then, the process switching 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 performed, the process switching process lock bit 20 is examined at a constant time interval, and the process is reset.

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

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

When the process selection process ends, the roll-out process starts. If the roll-out process completion flag is set at this time, the roll-out process is not performed and the next roll-in process starts. If the rollout process completion flag is not set, the rollout process is performed.

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

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

While the process switching process lock bit is set, attempts by other processors 1i will be unsuccessful. As soon as the other processor 1i receives the lock failure, it performs the rollout process, sets the rollout completion flag after the end of the rollout process, and issues the lock request again. The lock request is repeated until the lock success is received, and when the lock success is received, the process selection processing is performed.

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

[0020]

As described above, conventionally, when one processor is executing the process switching process and another processor attempts to start the process switching process, it waits for the process switching process to start. On the other hand, the present invention can shorten the processing time after the start of the process switching processing by executing the rollout processing prior to the process switching processing start waiting time, and as a result, the competition of the process switching processing in the system can be reduced. Has the effect of reducing.

[Brief description of drawings]

FIG. 1 is a process flow chart of an embodiment of the present invention.

FIG. 2 is a block diagram showing an 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 processing completion flag 2 System control device 20 Process switching processing lock bit 3 Main storage device

Claims (2)

[Claims] 1. In a process switching method in an information processing apparatus comprising a plurality of processors and controlled to perform process switching processing only on a single processor at the same time, each processor is provided with rollout processing of a process being executed A flag that is set at the end of the process and reset at the end of the process switching process is provided, and when any one processor tries to start the process switching process, a processor other than the one processor is performing the process switching process. In the case of, if the process that was being executed on the arbitrary one processor is rolled out, the flag is set, and a processor other than the arbitrary one processor completes the process switching process, the arbitrary one processor Starts the process switching process, If the flag is set, the roll-out process performed during the process switching process is controlled so as not to be performed, and the flag is reset when the process switching process is completed. 2. The process switching method according to claim 1, wherein the plurality of processors share a single main memory.