JPS6361698B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Industrial Application Field The present invention provides a polling control method, particularly a polling control method in which a host processing device performs repeated polling at a predetermined timing. The present invention relates to a polling control method in which an input/output control device returns pseudo status information when it is not possible to return desired status information from an input/output device for the time being.

(B) Problems to be solved by the prior art and the invention For an input/output control device to which multiple input/output devices are connected, a host processing device issues polling corresponding to each input/output device, and performs input/output control. Status information from individual input/output devices is sent back via the output control device.

In such polling control, the polling cycle is determined in consideration of cases where the input/output device and/or input/output control device is unable to return status information within a predetermined period due to execution of an instruction, etc. It will be done. However, in this case, if an instruction with a long execution time is sometimes executed, it becomes necessary to set the polling cycle to be undesirably long.

(C) Means for solving the problem The present invention is an attempt to solve the above problem, and when it is difficult to return the desired status information, the input/output control device Pseudo status information is sent back to the device to prevent the polling cycle from becoming undesirably long. Therefore, the polling control method of the present invention includes an input/output control device to which a plurality of input/output devices are connected, and a data processing device that has a host processing device that repeatedly polls the input/output control device at a predetermined timing. In the processing system, the input/output control device includes a control unit that sends a control signal to each of the input/output devices, and transfers the polling to each of the input/output devices in response to the polling. a polling transfer unit that transfers status information from each of the input/output devices to the host processing device in response to the polling; a status information transfer unit that transfers at least the most recent status information from each of the input/output devices to the host processing device; The status memory held for each input/output device, and when the above status information from the input/output device cannot be returned in response to polling of the input/output device from the host processing unit, the above status memory is stored.
Equipped with a pseudo status information return function that returns pseudo status information corresponding to the relevant input/output device on the memory to the host processing device, and the host processing device performs polling processing based on the returned status information or pseudo status information. The feature is that it is designed to do the following. This will be explained below with reference to the drawings.

(D) Embodiment FIG. 1 is an explanatory diagram illustrating an embodiment of polling control performed in the present invention, and FIG. 2 shows a main part configuration of an embodiment of an input/output control device used in the present invention.

In the case shown in Figure 1, there are four input/output devices as shown by #1 to #4, and each device is polled at a predetermined period as shown by the solid line.
A, 2A, 3A, 4A, 1B, 2B... is applied, and response status information 1A, 2A, 3A, 4
A, 1B, . . . are shown as being returned as indicated by dotted line arrows. Under such polling control conditions,
Now, suppose that when polling 1B, 2B, and 3B are applied, the input/output control device is executing an instruction as shown in the diagram "instruction execution", and the original status information 2
Suppose that it becomes impossible to return B and 3B. In the case of the present invention, in such a case, status information 2A (corresponding to pseudo status information according to the present invention) from one cycle before is returned as the status information corresponding to device #2, and
In response to this, pseudo status information 3A is also sent back.

By doing so, it is not necessary to make the polling cycle undesirably long due to "instruction execution" that may occur by chance.

In FIG. 2, 1 is an input/output control device, 2 is a control section, 3 is a status memory, and 4 and 5 are selectors, respectively. Note that illustrated route A is a transfer route corresponding to the polling transfer section, and illustrated route B is
indicates a route for transferring control signals, illustrated route C indicates a transfer route corresponding to the status information transfer section, and illustrated route D indicates a route corresponding to the pseudo status information return function.

In the figure, when polling from the host processing device side is repeatedly issued at a predetermined timing as shown in FIG.
Correspondingly, a predetermined input/output device returns its own status information at that point in time. At this time, in the input/output control device 1,
The status information is stored in the status memory 3 corresponding to each input/output device (overwriting past status information), and the returned status information is sent to the host processing device side via the selector 5. Transfer to.

Normally, polling control is executed in the manner described above, but the polling control shown in FIG.
As shown in B and 3B, it is assumed that the input/output control device 1 is unable to return the status information 2B and 3B to the host processing device side due to "instruction execution" or the like. The situation in this case is known to the control unit 2, and based on instructions (not shown) from the control unit 2, past status information stored in the status memory 3
A and 3A (corresponding to the pseudo status information according to the present invention) are read and sent back to the host processing device side via the selector 5 (via route D) as corresponding to the polling 2B and 3B. .

(E) Effects of the Invention As explained above, according to the present invention, it is sufficient for the host processing device to repeatedly issue polling at a predetermined timing, and the polling cycle can be made undesirably long. There's no need to do that.

Note that if the return of the status information corresponding to the polling is undesirably delayed, a time-out condition will occur on the host processing device side, but if, for example, the immediately preceding status information is returned as in the case of the present invention, the above-mentioned situation can be avoided. This eliminates the occurrence of time overs and prevents the status of the input/output device from becoming extreme. In the case shown in Figure 1, for input/output device #2, the host processing device receives status information 2A, 2A, and 2C, but needless to say, even if this happens, polling cannot be performed. The period has been chosen appropriately so that there are no problems caused by missing status information 2B.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating an embodiment of polling control performed in the present invention, and FIG. 2 shows a main part configuration of an embodiment of an input/output control device used in the present invention. In the figure, 1 is an input/output control device, 2 is a control unit, 3 is a status memory, 4 and 5 are selectors, and A
denotes a route corresponding to the polling transfer section, B a route for transferring a control signal, C a route corresponding to a status information transfer section, and D a route corresponding to a pseudo status information return function.

Claims (1)

[Claims] 1. In a data processing system that includes an input/output control device to which a plurality of input/output devices are connected, and a host processing device that repeatedly polls the input/output control device at a predetermined timing, the input/output control device is , a control unit that sends a control signal to each of the input/output devices, and a polling transfer unit that transfers the polling to each of the input/output devices in response to the polling; a status information transfer unit that transfers status information from each of the input/output devices to the host processing device; a status memory that retains at least the previous status information from each of the input/output devices for each input/output device; , and a pseudo status corresponding to the input/output device in the status memory when the host processing unit is in a state where the status information cannot be returned from the input/output device in response to polling of the input/output device. A polling control characterized in that a pseudo status information return function is provided to send information back to the host processing device side, and the host processing device performs polling processing based on the returned status information or pseudo status information. method.