JPH0646391B2 - Data transfer device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a channel program execution control system in a data transfer device. In particular, it relates to a processing method for responding to a command repeat or command retry request from an input / output device.

[Description of Prior Art]

2. Description of the Related Art Conventionally, a processing device of this type has a channel command word (hereinafter abbreviated as CCW) to be executed by a command repeat or command retry request set in advance when receiving a command repeat or command retry request from an input / output device. ) Load the channel command word from main memory by the stored main memory address of
After exchanging and editing the optimum information necessary for executing the data transfer of this channel command word (hereinafter, a series of processing including loading, exchanging and editing of the above channel command word is described as "CCW fetch"). Yes.),
The data transfer is started by giving the information after the execution of the "CCW fetch" to the data transfer unit and the corresponding channel in the channel control device.

This "CCW fetch" is performed by the microprogram in the channel controller but cannot be completed immediately in a short time. Especially, the main memory address in the channel command word is described by the theoretical address. In a device having a channel DAT function that performs data transfer after converting to an absolute address at the time of command overrun (machine of Often, the command code sent from the channel to the I / O device will not be in time due to the constant speed), and data overrun (also the data transfer between the channel and the I / O device will not be in time). It was a cause of occurrence.

Further, generally, one microprogram exists in the channel control device and controls a plurality of subordinate channels, so that when one channel is controlled, another channel waits for a control request to the microprogram. However, since the "CCW fetch" is performed again by the command repeat request or the command retry request from the input / output device, the processing time of the microprogram becomes long, and the control request of another channel which is not under control is waited. It was a cause of increasing command overrun and data overrun of the channel.

[Object of the Invention]

The present invention solves the above-mentioned conventional drawbacks, and a retry provided in a channel-corresponding control table having "CCW fetched" information in the main memory when starting data transfer designated by a channel command word. It is stored in the information area and is intended to prevent command overruns and data overruns.

In particular, when a command repeat or command retry request from the input / output device is accepted, the data stored in the retry information area is restarted to restart the data transfer, and thus the input / output device requesting the command repeat or command retry is restarted. It responds in a short time and aims to prevent command overrun and data overrun in data transfer with the channel being controlled as much as possible, and in addition, finishes processing by command repeat or command retry request of microprogram in a short time, The purpose is to reduce command overruns and data overruns on other channels by immediately starting control of the other channels.

[Characteristics of the Invention]

Multiple channels that can execute command repeat or command retry functions according to requests from input / output devices,
In a data transfer device including a channel control device for controlling this channel and a main storage device having a control table corresponding to the channel, a retry information area secured in the control table and at least a command issued by the channel control device. When data transfer specified by a channel command word including a code, control flag, transfer byte number, and main memory address information is started, the information contained in the channel command word and the absolute data area in the main memory converted from this information Means for storing address information in the retry information area, and resuming data transfer by the information stored in the retry information area when the channel control device receives the command repeat or command retry request from the input / output device Characterized by having means To.

[Explanation of Examples]

Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a data transfer device according to an embodiment of the present invention. In this embodiment, a main memory device (hereinafter referred to as MEM
A main memory control device (hereinafter referred to as M
A central processing unit (hereinafter C) is provided on the output side of the CU 11.
PU 12 and channel controller (hereinafter referred to as CHC)
Abbreviated as 13) are connected. The channel control device 13 has a plurality of input / output devices (hereinafter abbreviated as I / O) connected via I / O interfaces 15 of respective channels (hereinafter abbreviated as CHU) 14 respectively.
It is composed of 16. The central processing unit 12 and the channel control unit 13 can access the main storage unit 10 via the main storage control unit 11, and the central processing unit 12 and the channel control unit 13 can communicate with each other via the main storage control unit 11. Is. The channel control device 13 can control a plurality of channels 14, and the channel 14 can perform a data transfer operation with a plurality of input / output devices 16 via an I / O interface 15. Main memory 10 for each channel 1
4 and a control table corresponding to each input / output device 16 (hereinafter LCE).
For short).

FIG. 2 is a block diagram of the channel controller 13. The channel control device 13 includes a channel control unit (hereinafter abbreviated as CMU) 21 and a data transfer unit (hereinafter C as a unit) on the output side of a memory access unit (hereinafter abbreviated as MAC) 20.
22 and 22 are connected and connected to each other, and outputs of the channel control unit 21 and the data transfer unit 22 are connected to inputs of a channel connection unit (hereinafter abbreviated as CPC) 23. The channel connection unit 23
A plurality of channels 14 are connected to the output of. The memory access unit 20 includes a channel control unit 21 and a data transfer unit 22.
In response to a request from the main storage device 10, the main storage device 10 is accessed and communication with the central processing unit 12 is performed. The channel control unit 21 is controlled by a microprogram and controls communication with the central processing unit 12.
It controls the execution of the channel program, decodes the request from the input / output device 16, and gives the information necessary for the data transfer to the data transfer unit 22 and the channel 14 to instruct the operation. The data transfer unit 22 transfers data between the main storage device 10 and the channel 14 via the main storage control device 11, the memory access unit 20, and the channel connection unit 23 according to the information given from the channel control unit 21. The channel 14 is the input / output device 1 according to the information given from the channel controller 21.
6 is controlled, and data is transferred between the data transfer unit 22 and the input / output device 16 via the channel connection unit 23 and the I / O interface 15.

FIGS. 3 (a) and 3 (b) show the channel command word (CCW) of the channel program and this (CCW) as the main storage device 10.
The data after "CCW fetch", which has been loaded from, converted into the optimum data necessary for causing the data transfer unit 22 and the channel 14 to execute the data transfer, and edited, is shown.

That is, the command code (CMD) 30 and the control flag (FL
G) 31 to command flag (CFLG) 35; transfer byte number (BC) 32 to transfer byte number (BC) 36; transfer byte number (BC) 32 and main memory logical address (EDA) 3
3 to number of pages (PGCT) 34; main memory logical address (EDA) 33 to main memory absolute address (ADA) 37
And page table address (PTA) 38 are converted and edited respectively.

The number of pages (PGCT) 34 and the page table address (PTA) 38 in the figure are used to reconvert the main memory absolute address (ADA) 37 when the page of the main memory is updated during data transfer. Command flag (CFLG) 3
5, the transfer byte number (BC) 36 is stored in the data transfer unit 22, the channel 14, and the main memory absolute address (ADA) 37.
Is supplied to the data transfer unit 22 and serves as control information for data transfer.

The information shown in FIG. 3 (b) is the information stored in the retry information area 44 described later.

When a so-called chain command or chain data is most likely to be executed next in the execution of a channel program, the "CCW fetch" that is most likely to be executed next is performed in advance is called "CCW prefetch".

The "CCW prefetch" and "CCW fetch" are performed by the microprogram of the channel control unit 21,
The processing time becomes long, and particularly the processing time for converting the main memory logical address 33 into the main memory absolute address 37 becomes long.

FIG. 4 shows the format of the control table under the control of one channel control device 13 existing in the main storage device 10. There is an area in the main storage device 10 that cannot be directly accessed by software and is uniquely defined and used by the hardware of the central processing unit 12 and the channel control device 13. This area is called an "underbar area". The control table exists in this "underbar area". The control table 40 of the illustrated channel controller is the channel controller 13
The corresponding control table and channel control table 41 is a control table corresponding to the channel 14, and the input / output device control table 42 is a control table corresponding to the input / output device 16. The channel control table 41 includes a control information area 43 for managing the state of the channel 14 and a channel program being executed on the channel 14, and a retry information area 44 which is one of the constituent features of the present invention.

FIG. 5 shows a data transfer unit 22 according to information after "CCW prefetch" or "CCW fetch" in which a microprogram in the channel control unit 21 has been stored in a storage unit (for example, a scratch pad memory) in the channel control unit 21,
8 is a flowchart of a routine for instructing data transfer to the channel 14, and by storing all the contents of the information in the retry information area 44 after completion of this instruction, information necessary for command repeat or command retry request from the input / output device 16 Store and put.

FIG. 6 shows a command repeat in which the microprogram in the channel controller 21 decodes the request code from the input / output device 16 and requests the repetition of the same channel command word.
Command retry requesting the retry of the same channel command word (Both command repeat and command retry are requested by the input / output device while the channel command word chained by chain data is being executed. It is restarted from the word.) It is a flowchart which performs the process which checks whether it is a request and responds when it is the request. Command repeat,
If it is a command retry request, the "CCW fetch" process is not performed again, and the data transfer unit 22 and the channel 14 are instructed to transfer data by the contents of the retry information area 44.

Here, the reason for restarting from the first channel command word of the chain data when a command repeat or command retry request is accepted during execution of a channel command word chained by chain data will be described.

A plurality of channel command words chained by the chain data are equivalent to one channel command word when viewed from the input / output device. Chain data uses the command in the first channel command word of the chain data, and the area of multiple main memory specified in the multiple channel command words chained by the chain data that includes this first channel command word. This is a function to transfer data between the input and output devices. In both the command repeat and the command retry, the input / output device receives the command corresponding to the data transfer currently being executed from the channel again and re-executes it, so that the channel command word at the beginning of the chain data is naturally restarted.

The minimum required to execute command repeat or command retry is the address of the channel command word being executed if it is not chained with chain data, or the channel command at the beginning of chain data if it is chained with chain data. Is the address of a word.
When a command repeat or command retry request is received from the I / O device, the channel information word at the beginning of the data transfer is restarted.
The data transfer unit 22 and the channel 14 are instructed to transfer data according to the contents of No. 4, but the second and subsequent channel command words are the addresses of the channel command words held in the same manner as in normal execution. Is fetched from the main memory, the logical address in the channel command word is converted into an absolute address, and the data is transferred.
However, for the second and subsequent channel command words, that channel command word can be fetched before it is actually needed, and the logical address in the channel command word can be converted and placed as an absolute address, so command overrun, data over Runs can be reduced.

Search-type commands are equivalent to write-type commands when viewed from the channel controller. Regarding command repeat and command retry, search commands are executed in the same manner as write commands.

The TIC command is invisible to the I / O device. The channel controller performs an unconditional branch of the channel program by the TIC command, and continues the channel program by the channel command word of the branch destination. Therefore, since the input / output device does not request the command repeat and the command retry for the TIC command, no special consideration is required.

[Explanation of effects]

According to the present invention, as described above, the retry information area holds the information included in the channel command necessary for channel control and the absolute address information of the data area in the main memory converted from this information. Data can be transferred in response to a command repeat request or a command retry request from the device, and the processing time of the microprogram can be shortened, and command overrun and data overrun can be easily reduced in the channel control device.

[Brief description of drawings]

FIG. 1 is a system configuration block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram of the channel control device. FIG. 3 (a) is a channel command word format diagram. FIG. 3 (b) is a data format diagram after completion of the channel command word "CCW fetch". FIG. 4 is a control table format diagram under the channel control device in the main memory. FIG. 5 is a flow chart when the microprogram stores information in the retry information area. FIG. 6 is a flowchart of a process in which the microprogram responds to a command repeat or command retry request from the input / output device. 10 ... Main memory unit (MEM), 11 ... Main memory control unit (MCU), 12 ... Central processing unit (CPU), 13
...... Channel control unit (CHC), 14 ...... Channel (CHU), 15 ...... I / O interface, 16 ......
Input / output device (I / O), 20 ... Memory access unit (M
AC), 21 ... Channel control unit (CMU), 22 ...
Data transfer unit (CDU), 23 ... Channel connection unit (C
PC), 30 ... Command code, 31 ... Control flag, 3
2 ... Transfer byte number, 33 ... Main memory logical address, 3
4 ... Page number, 35 ... Command flag, 36 ... Transfer byte number, 37 ... Main memory absolute address, 38 ... Page table address, 40 ... Channel control unit control table (IOCE), 41 ... Channel control table (PCE), 42 ... Input / output device control table (LC
E), 43 ... Control information area, 44 ... Retry information area.

Continuation of the front page (56) Reference JP-A-58-40644 (JP, A) JP-A-54-51741 (JP, A) JP-A-51-23044 (JP, A) JP-A-48-20446 (JP , A) JP-A-54-133852 (JP, A) JP-A-55-124826 (JP, A) Masami Yamatani, "Introduction to Virtual Computer System for Illustrated Computer Series", Ohmsha, October 10, 1978. Issued, PP. 97-100

Claims (1)

[Claims] 1. A plurality of channels for executing a command repeat or command retry request from an input / output device, a channel control device for controlling the channels, and a main storage device having a control table corresponding to the channels. In the data transfer device, the retry information area secured in the control table, and the data transfer specified by the channel control device by a channel command word including at least a command code, a control flag, the number of transfer bytes, and main memory address information. Means for storing the information contained in the channel command word and the absolute address information of the data area in the main memory converted from this information in the retry information area when the channel command word is started from the input / output device. Command repeat or command repeat Lai upon receiving the request data transfer apparatus characterized by comprising a resuming unit data transfer by the information stored in the retry information area.