JPS599925B2 - Priority processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a priority processing system, and in particular to a system comprising a control device and a large number of controlled devices controlled by the control device, in which the control device has 15 controlled devices. The present invention relates to a priority processing method for request acceptance in a system in which other controlled devices are forced to wait even if they send a processing request signal to a control device and must resend the processing request signal later.

20 In the case of a device system consisting of a control device and a large number of controlled devices that transmit processing request signals to the control device, the control device starts processing of the controlled device based on the processing request signal from the controlled device, When a large number of controlled devices simultaneously issue processing request signals one after the other, if the 25 control devices are able to accept processing, the processing for the controlled device that sent the signal earliest is started; If not, other requests will have to wait until processing can be accepted.

Depending on the device system, requests made to wait can be handled by creating a queue and starting processing in the order in which the processing requests were sent or in the reverse order;
Commonly used methods include creating a queue and starting processing in order of priority among the queues, and a method of not creating a queue and transmitting a processing request again at a later time.

35 Now, the input/output device system of a computer consists of several channel processing devices and a large number of input/output devices, especially a large number of large storage devices.The channel processing device controls the input/output devices, that is, selects the input/output devices. , sends input/output commands, monitors the status of input/output devices, retrieves data transfer requests from input/output devices, transfers data to input/output devices, etc.

When a channel processing device controls a large storage device, such as a drum device or a disk device, it first issues data read/write commands to these devices. By issuing this command, the channel processing device and its large storage device are temporarily disconnected, and the channel processing device then starts other processing. When the large storage device receives the read/write command, the address on the circumference from which data is to be read/written on the rotating storage medium rotates just before the magnetic head for reading/writing, and the data is read/written. Sends a processing request signal to start transfer. At this time, if the channel processing device is not able to accept the request, the large storage device is made to wait again, and when the read/write portion on the medium rotates once and is in a position where it can start data transfer again, the processing request signal is sent to the channel. Send to processing equipment. When the data transfer request is accepted, the channel processing device and the large storage device are connected again, and data transfer is started. By the way, in an electronic computer, a large number of large storage devices that store online data and large storage devices that store batch data are controlled by several channel processing devices.

Data transfer in a large online storage device must be completed in a short time, while data transfer in a batch storage device can be delayed. Traditionally, both online and batch large storage devices have been given priority.
A method for selectively selecting processing request signals has not been developed. There was a drawback that the online data transfer time was insufficiently designed for transfer.

jThe purpose of this invention is to overcome the above-mentioned drawbacks, and this purpose is to provide a control device comprising a control device and a large number of controlled devices that transmit processing request signals to the control device to trigger the start of processing. ,
If the control device is not capable of accepting four processes at the time the controlled device sends the processing request signal, a time counting means is installed in the device system that sends the processing request signal again later, and the controlled device that has been kept waiting for a certain period of time is From then on, the control device becomes able to accept requests and continues to send processing request signals until the processing request is accepted, and starts processing processing requests that have been waiting for a certain period of time with priority, thereby reducing the upper limit of the processing time. This is achieved through a priority processing method as specified.

This invention will be explained in detail below with reference to the drawings.

FIG. 1 is a diagram showing an example of the connection of a large storage device in a computer system, and FIG. 2 is a diagram showing the configuration of an embodiment of the large storage device based on the present invention.

In FIG. 1, 11 is a central processing unit, 12 is a channel processing unit, 13 is a main storage device, 21-23 and 31-
33 is a large storage device such as a magnetic drum or a disk. In FIG. 2, 12 is a channel processing device, and 21 is a large storage device.

51 is an interface control unit, 52 is a sequence register, 53 is a read/write circuit, 54 is a read/write magnetic head, 55 is a target register, 56 is a sense circuit, 57 is a match circuit, and 58 is an interrupt circuit. It is.

61 is a number counting circuit based on the present invention, 71 is a subtraction generation circuit, 72 is a maximum counter, 73 is an arithmetic circuit,
74 is a determination circuit.

In FIG. 1, when the central processing unit 11 sends an input/output command to the channel processing unit, the channel processing unit 12 sends the input/output command if the large storage device, for example, the large storage device 21 that is the target of the input/output command, is available. , receives the input/output command, and transmits the input/output command to the large storage device 21.

When the large storage device 21 accepts this command, the connection between the channel processing device and the large storage device 21 is severed, and the channel processing device starts processing to another large storage device. Large storage device 2
1 reads the input/output command received from the channel processing device 12, determines the address on the large storage medium to be read/written, and reads the specified address on the large storage medium attached to the large storage device 21, that is, When an arc on a specified circumference on the large storage medium reaches the read/write head position, and when the arc to be read or written reaches the read/write position, the channel processing device 12 Sends a processing request signal. At this time, if the channel processing device is processing another large storage device and cannot accept the request, the large storage device 21 becomes rotary and reads/writes again.
When the arc to be written is at the read/write head position, a processing request signal is sent to the channel processor 12. When this request is accepted by the channel processing device, the main storage device 13, channel processing device 12, and large storage device 21 are connected, and read/write data transfer is started. When the data transfer is completed, the connection between the main storage device 13, channel processing device 12, and dog storage device 21 is again disconnected, and the channel processing device 12 issues an interrupt to the central processing unit to indicate the end of the input/output command. In FIG. 2, when the large storage device 21 receives an input/output command from the channel processing device 12, the interface control section 51 sets its read/write address in the target register 55.

The output of the sense circuit 56 and the value of the target register 55 are detected by the match circuit 57, and when a match is found, the interrupt circuit 5
8 sends a processing request signal to the channel processing device. When this processing request is accepted by the channel processing device 12, the data transferred to and from the main storage device is transferred to the interface control unit 5.
1. The data is read/written to a rotating medium (not shown) via the sequence register 52, read/write circuit 53, and magnetic head 54. For the above functions, the time counting means according to the present invention, when this device sends a processing request, performs a fixed number of checks determined from the rotational speed of the recording medium until the sending request is accepted by the channel processing device. A frequency counting circuit 61 is provided to count the maximum number of waiting rotations by utilizing the characteristic of transmitting a processing request signal. The interface control unit sets a maximum capacity counter 72 when receiving an input/output command, and sends a signal to the subtraction generation circuit 71 every time the matching circuit 57 issues a processing request signal. Here, the subtraction generating circuit 71 is 7
The value of -1, , is sent to the arithmetic circuit 73, and the value of the maximum holding counter 72 is subtracted by 1. The determining circuit 74 determines whether the value of the maximum holding counter becomes zero, and if it is not zero, it sets that value again in the maximum holding counter 72, and when the result of the subtraction becomes zero, it sends a signal to the interrupt circuit 58. In response to this signal, the interrupt circuit 58 continues to send processing request signals until the processing request is accepted by the channel processing device 12, and processing requests that have waited for a certain period of time or longer are processed preferentially. Note that the value of the maximum duration counter can be fixed to the large storage device, and by using this method, it is possible to set the maximum duration for each large storage device.

Also, the value of this maximum counter can be designed so that it can be changed freely on the channel processing device side.
Using this method, the channel processing device can dynamically change the priority of each large storage device depending on the transmission status of input/output commands. Furthermore, the value of this maximum counter can be designed so that it can be specified in the input/output command sent from the central processing unit to the channel device, and by using this method, the maximum duration can be set for each input/output command. It becomes possible to do so. In an actual computer system, a large number of large storage devices are cross-connected to several channel processing devices, so that rotational locking occurs when none of the channel processing devices is able to accept requests.

However, due to the large number of large storage devices and the large number of data transfer requests, rotational locking occurs frequently, and the method of the present invention has made it possible to efficiently solve the rotational locking problem. In a device system other than a computer, if one control device can process n items at the same time and controls m controlled devices at a time (n<m), requests after the (n+1)th The technique based on this invention can preferentially solve problems.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electronic computer system, and FIG. 2 is a block diagram of an embodiment of a large storage device based on the present invention. In FIG. 1, 11 is a central processing unit, 12 is a channel processing unit, 13 is a large storage device, and 21-23 and 31-33 are large storage devices.

Claims (1)

[Scope of Claims] 1 A processing request signal is intermittently transmitted to a control device until a request is accepted, and after the request is accepted by the control device, a predetermined process is performed based on the control of the control device. In a priority processing method in a system equipped with a large number of controlled devices, the controlled device generates a signal to determine whether a predetermined time has elapsed after the first processing request signal from a predetermined controlled device is generated. A time monitoring means is provided for monitoring by counting periodic signals, and if a request is not accepted by the controlled device before the predetermined period of time has elapsed, the controlled device continuously sends a request until the request is accepted. A priority processing method characterized by generating a processing request signal. 2. Once the processing request signal has started to be transmitted, the time monitoring means is used to send the processing request signal to the group of controlled devices that send the processing request signal at regular intervals until the processing request is accepted by the control device. The priority processing system according to claim 1, characterized in that it is constituted by a number counting means for counting the number of times. 3. The priority processing method according to claim 1 or 2, characterized in that the value of the predetermined time is set for each controlled device. 4. The priority processing method according to claim 1 or 2, wherein the value of the predetermined time can be changed by a control device. 5. The priority processing method according to claim 1 or 2, wherein the predetermined time value is supported each time the control device starts up the controlled device.