JPH10154116A - Data transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer transmitting data without buffering by an operating system (OS). SOLUTION: In a computer 100 at a sending end, an OS 105 communicates with an OS 205 and collectively confirms whether transmission destination user programs 203 of plural transmitting data which are designated by plural user programs 103 are separately in a receivable state. When a user program 204 at a receiving end does not issue a receiving request, the OS 105 regards the program as unreceivable, collects the transmission of plural transmitting data which are decided as transmittable and instructs a communication device 112. In the device 112, a DMA circuit 113 directly and continuously reads the transmitting data from the buffer 104 of each user program 103, and a communication circuit 114 separately transmits the transmitting data via a channel 300. In a computer 200 at the receiving end, a DMA circuit 213 directly and continuously writes each transmitting data on the buffer 204 of a user program 203 of a transmission destination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication method between computers connected by a transmission line.

[0002]

2. Description of the Related Art As a conventional data transfer method between computer systems, a high-level data link control procedure (H
DLC: High Level Data Link
Control). For example, “Data Communication”, edited by the Data Communication Board of Education, Kyoritsu Shuppan, pp. 146-64. 46--53
(1982), “High Level Data Link Control Procedure (HDLC: High Level Data Li)
nk Control ”). HDLC is a data transfer method in which a transmitting computer sends a transfer notification to a receiving computer, and data is transferred after a response is returned from the receiving computer. This data transfer method can be applied to data transfer between computers connected by a direct data transfer path. This HDLC procedure is suitable for high-speed transfer since data can be directly transferred between user programs, but cannot be applied to data transfer between arbitrary user programs controlled by the OS. HDLC
In order to speed up the data transfer by the procedure, the transmission circuit of the transmission side computer is provided with a DMA circuit for continuously reading the transmission data in the buffer of the transmission side program, and the received data is transmitted to the reception circuit of the reception side computer. There is also a device for providing a DMA circuit that continuously writes data in the buffer of the program on the receiving side.

Each operating system (O
As a method of transferring data between arbitrary user programs controlled by S), TCP / IP (Transmission)
ionControl Protocol / Inter
net Protocol). For example, the translation of "Akira Nakamura / Jin Aida / Keio / Kohei Panpei" UNIX
4.3 Design and Implementation of 3BSD ”Maruzen, pp. 169-18
5 (1991) (Original work: The Design and
Implementation of the 4.
3BSD Operating System, original author: S.M. J. Leffler / M. K. McKusic
k / M. J. Karels / J. S. Quarterm
an, Original Issuer Addison Wesley).
This data transfer method can also be used for packet data transfer between arbitrary computers connected by a computer network via another computer.

In this method, the OS performs buffering so that a plurality of user programs can simultaneously transfer data. That is, in the sending computer, the OS
Copies the data to be transmitted from the buffer area allocated to the user program to the buffer in the OS. At this time, a packet header is added to the copied data. The transmission data and the packet including the header are transmitted by the transmission circuit to the receiving computer via the network. In the receiving-side computer, the receiving circuit stores the received packet in a buffer in the receiving-side OS, and the receiving-side OS determines the user program of the receiving destination from the header of the written packet. When a reception request comes, the data in the received packet in the buffer of the receiving OS is copied to the buffer of the program on the receiving side. At this point, the receiving OS notifies the sending OS of the completion of the reception. In this data transfer method, the length of data transmitted in one packet is fixed to the size of buffers for the transmitting OS and the receiving OS. When transferring data exceeding the size of the buffer, the data is divided according to the size of the buffer, and a plurality of divided partial data are transferred by a plurality of packets. In the OS of the transmitting computer and the OS of the receiving computer, activation processing and termination processing of the communication device are performed for each packet.

In this transfer method, since the received data is temporarily stored in a buffer in the OS on the receiving side, the user program on the receiving side can issue a receiving request asynchronously with the transmission of the data. If the data transmission is unsuccessful, the OS on the transmitting side retransmits the transmission data in the buffer for the OS. Therefore, the user program on the transmitting side can request the OS on the transmitting side to transmit data regardless of whether the user program on the receiving side is in a receivable state. After being copied to the buffer, other processing can be executed without waiting for the data transfer to be completed.

In order to perform high-speed data transfer by this method, a DMA for continuously reading transmission data from a buffer of an OS of a transmission side is provided in a transmission device of a transmission side computer.
A circuit is provided and a DMA circuit for continuously writing received data to a buffer of the receiving OS is provided in the receiving device of the receiving computer. For example, Masayuki Yamai, "Ethernet Board &Card", Open Design, No. 3, CQ Publishing, pp. 109-
-113 (1994).

[0007]

In the data transfer by TCP / IP, data is copied between the buffer of the user program and the buffer of the OS in both the computer on the transmitting side and the computer on the receiving side. The time required for the data copy processing increases in proportion to the data amount, and the ratio of the data copy time to the data transfer time increases. As a result, there is a problem that even if the computers are connected by a high-speed transmission line, the data transfer speed by this method is not so much improved. As described above, this problem remains even if the DMA circuits are provided in both the transmission circuit of the transmitting computer and the receiving circuit of the receiving computer. Particularly in the field of scientific computers, it is necessary to continuously transfer a very large amount of data between computers, and the problem of the data copy time becomes extremely large.

Further, according to this method, when transferring data exceeding the size of the buffer for the transmitting OS and the receiving OS, as described above, a plurality of partial data obtained by dividing the data is divided into a plurality of packets. Transfer by
At this time, the OS of the transmitting computer and the OS of the receiving computer
Then, the start-up process and the end process of the communication device are performed for each packet. As the size of this data increases, the number of packets required to transfer it increases,
There is a problem that it takes time for the start-up process and the end process of the communication device to be performed by these OSs, thereby reducing the data transfer speed. This problem also increases when a very large amount of data is continuously transferred between computers as in the field of scientific computers.

[0009] TCP / IP data transfer can be used for data transfer via a large number of computers, but the data transfer speed is reduced due to the transfer. 2. Description of the Related Art In a system for scientific and technical calculations, it is desired to transfer data between specific computers connected by a transmission line at a higher speed without passing through other computers.

Accordingly, an object of the present invention is to provide a data transfer method for transferring data at a higher speed from a user program controlled by an OS of a transmitting computer to a user program controlled by an OS of a receiving computer, Another object of the present invention is to provide a data transfer method suitable for transferring a very large amount of data between user programs for scientific calculations without passing through another computer.

A more specific object of the present invention is to copy data between a buffer for a user program and a buffer for an OS on a transmitting computer and to copy data between a buffer for a user program and a buffer for an OS on a receiving computer. An object of the present invention is to provide a data transfer method for transferring data between user programs without performing data copy.

Another specific object of the present invention is to provide a data transfer method for transferring data specified by a user program of a transmitting computer to a user program of a receiving computer without dividing the data.

[0013]

In order to achieve the above object, a data transfer according to the present invention comprises first and second computers connected to each other by a transmission line, and the first and second computers are connected to each other. A computer executes a system having a processor, a main storage device, and a communication device that reads data stored in the main storage device, transmits the data to the transmission line, or receives data from the transmission line, and writes the data to the main storage device. Is done. First, it is determined whether or not data transfer is possible between the user program of the transmission source executed by the first computer and the user program of the transmission destination executed by the second computer. The determination is made by communication between the first OS and the second OS that controls the second computer. If it is determined that data transfer is possible between those programs, the OS
In accordance with the instruction from, the communication device of the transmitting computer and the communication device of the receiving computer directly transfer data between these user programs without passing through their OS. More specifically, (a) the data stored in the first area for the source user program is transmitted to the destination user program executed by the second computer by the source user program. Issue a transmission request to the first OS, and (b) send the second OS
S, inquires whether the destination user program is in a data receivable state, and (c) the second OS determines whether the destination user program is in a data receivable state, The second OS notifies the first OS of the inquiry result indicating the determination result, and (d) the second OS
Determines that the destination user program is in a data receivable state, the second OS receives the data specified by the transmission request and sends the data to the second area for the destination user program. (E) When the inquiry result indicates that the user program of the transmission destination is in a data receivable state, the OS of the transmission-side computer transmits the data. To the communication device of the transmitting computer, (f) reading data from the first area for the source user program by the communication device of the first computer, transferring the data to the second computer via a transmission path, (G) The data is received by the communication device of the second computer and is written to the second area for the destination user program.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a data transfer method according to the present invention will be described in more detail with reference to embodiments shown in the drawings.

<Embodiment of the Invention> (1) Overview of System Configuration and Operation In the computer system shown in FIG.
200 includes processors 101 and 201, main storage devices 102 and 202, and communication devices 112 and 212, respectively. These communication devices are connected by a channel 300 which is a high-speed and highly reliable transmission path. Are directly connected via this channel 300 without going through other computers. The communication devices 112 and 212 respectively include a direct memory access (DMA) circuit 113,
213, communication circuits 114 and 214, instruction execution circuit 1
15 and 215, and the DMA circuits 113 and 213 can directly read and write areas on the main storage devices 102 and 202, respectively. OS 105, 205 is communication device 1
When the communication devices 112 and 212 are started by storing the instructions to the communication devices 112 and 212 in the DMA control lists 111 and 211 prepared on the main storage devices 102 and 202, the instruction execution circuit 1
15 and 215 interpret the instructions stored in the DMA control lists 111 and 211 and execute the instructions given by controlling the DMA circuits 113 and 213 and the communication circuits 114 and 214. Similarly, the remaining instructions are sequentially executed, all the instructions are interpreted, and when the execution is completed, a hardware interrupt is generated to the OS 105 or 205 to report the completion of the instruction. The instructions stored in the DMA control lists 111 and 211 are (1) the main storage device 1
From where on 12, 212, (2) how much
(3) It is a list of an arbitrary number of DMA control commands consisting of a specified set of whether to transmit or receive.
When a pair of DMA control commands forming a pair is executed by both the communication devices 112 and 212, communication via the communication path 300 is established. The pair of DMA control instructions that form a pair is a set of transmission DMA control instructions and reception DMA control instructions of the same size. For example, in the computer 100, when the instruction execution circuit 115 interprets the instruction “transmit a size a from the address A of the main storage device 112”, the designated area (the size a from the address A) for the DMA circuit 113 And instructs to read the result to the communication circuit 112,
The data passed to the communication circuit 112 is
0 is output. In that case, the computer 200
The instruction given to the instruction execution circuit 215 must be “receive from the address B of the main memory 212 by the size a”. Then, the communication via the transmission path 300 is started from the time when both the transmission operation of the communication circuit 112 and the reception operation of the communication circuit 212 are performed. Communication circuit 11
2, 212 waits for the occurrence of a reception operation or a transmission operation when either the transmission operation or the reception operation occurs first.

In the main storage devices 102 and 202, a plurality of user programs 103 and 203 operate under the control of OSs 105 and 205 that control the computers 100 and 200. Each of the user programs 103 and 203 is assigned a unique program identifier in each computer, and the OS 105 and 205 can interrupt or restart the operation of the user program by specifying the program identifier.

Each of the plurality of user programs 103 includes:
After storing the transmission data in the buffer 104, the OS 10
5 is issued. The OS 105 transmits the transmission data stored in the buffer 104 in each user program 103 to the reception-side computer 200.
Instruct 2 In the communication device 112, unlike the related art, the DMA circuit 113 directly and continuously reads transmission data from the buffer 104 in each user program 103. The OS 105 instructs the communication device 112 to transmit the transmission data specified by each user program 103, but does not copy the transmission data to a buffer in the OS 105 unlike the related art. The communication circuit 114 transmits the transmission data read by the DMA circuit 113 to the computer 200 on the receiving side via the channel 300.

In the communication device 212 of the computer 200 on the receiving side, each time the communication device 214 receives the respective transmission data, unlike the conventional technology, the DMA circuit 213 causes the DMA circuit 213 to transmit the transmission data in the user program 104 in the transmission destination. The received data is directly and continuously written to the buffer 204 without passing through the OS 202 that controls the receiving computer.
The OS 205 differs from the prior art in that the received data is
It is not copied to the buffer in S205.

To transfer data by the above method,
It is necessary to synchronize the data transfer with the user program 203 on the receiving side. That is, the user program 203 of the transmission destination of the transmission data specified by each of the plurality of user programs 103 must be in a state where the data can be received. The state in which the user program 203 can be received is a buffer 2 for storing received data.
04 is prepared. In order to prevent data destruction due to overwriting of the buffer 204 when the buffer 204 is used repeatedly, the receiving user program 203 explicitly issues a receiving request to the OS 205 to confirm that the receiving preparation is completed, that is, Notify that it is possible. The reception request is issued by calling a reception reception program 206 described later. For this reason, in the present embodiment, the OS 105 collectively checks with the OS 205 whether the user program 203 of the transmission data destination specified by the plurality of user programs 103 is in a state capable of receiving data. After this confirmation, the communication device 112 is instructed to transmit a plurality of transmission data items specified by the user program 103 at once.

More specifically, the transmission reception program 106 in the OS 105 stores a plurality of transmission requests issued from the plurality of user programs 103 in the transmission request list 108, and the transmission processing program 107 A REQ command block 109 representing those stored transmission requests is created, and a DMA control list 1
11 is generated to instruct the communication device 112 to transmit the REQ command block 109. When the communication device 112 transmits this block 109 to the computer 200, the computer 20
0, one of the user programs 203
When data is to be received from any of the user programs 103 in the OS 00, a data reception request is sent to the OS 20.
5 and the reception accepting program 206 in the OS 205 transmits the reception request to the reception request list 2.
08.

When the communication circuit 214 receives the REQ command block 109, the DMA circuit 213 writes the REQ command block 209 in the main storage device 202, and the reception processing program 207 executes
ACK command or NACK indicating whether or not the destination user program specified by the REQ command block 209 is in a receivable state based on the reception request held in No. 8 and the written REQ command block 209. An ACK command block 210 including a command is created, and a DMA control list 211 is generated to instruct the communication device 212 to transmit the ACK command block 210. In the computer 100, upon receiving the ACK command block 210, the transmission processing program 107 attaches, based on the ACK command block 210, to only the transmittable ones of the previously transmitted REQ command blocks 109. Instruct the communication device 112 to transmit data.

The OSs 105 and 205 have the same structure, and each computer can transmit and receive data to and from the other computer. Therefore, the OS 105 in the computer 100 includes the reception reception program 206 and the reception processing program 2
07, a reception request list 208, and the OS 205 in the computer 200 has a transmission reception program 106, a transmission processing program 107, and a transmission request list 108. However, for the sake of simplicity, the drawing shows only those parts necessary when the computer 100 operates as a transmitting-side computer and the computer 200 operates as a receiving-side computer. Hereinafter, details of the data transfer method according to the present embodiment will be described with reference to the time chart of the operation of the main part shown in FIG. In the following, buffers 104 and 204, REQ command blocks 109 and 209, ACK command block 2
It is assumed that 10, 110 and the DMA control lists 111, 211 are continuously resident on the main storage device 102 or 202. The “continuous” area means that the area is continuously reserved on the physical main memory, not on the virtual memory, and the “resident” area is handled by a normal user program. Unlike the storage area, this means that the reserved area is always saved on the physical main storage without being saved to the disk device by the OS 105 or 205 as needed. This is because the main storage devices 102 and 202 cannot be recognized as virtual areas from the communication devices 112 and 212. Also, all command blocks 109, 210, 110, 209
Are assumed to be of equal size. It is assumed that information about the number of files to be transferred, the size of each file, and the like is clear in advance between the user programs on the transmission side and the reception side.

(2) Details of data transfer operation (A) Transmission-side computer 100 (part 1) Transmission of REQ command (A1) Issuance of transmission request from user program 103 on the transmission side It is assumed that the transmitting user program 103 is running and three receiving user programs 203 are running on the receiving computer.

Referring to the flowchart of FIG. 3, the processing of each of the three transmission-side user programs 103 has a double loop structure, and is used to hold a file to be transferred at the beginning and end of the processing. Transmission buffer 104
Is secured or released (steps 401 and 40).
8). The buffer 104 for each user program is allocated to the main memory 102 until it is released after it is allocated.
It shall be resident on and be used repeatedly throughout the entire process. The outer loop is a loop for processing a plurality of files, and the inner loop is a loop for transferring each file by a plurality of communications.

Each time the transmission-side user program 103 stores a part of the file to be transferred to the buffer 104 (step 402), it calls the transmission reception program 106 and sends a transmission request (step 403). If the result of calling the transmission reception program 106 is an error, the data transmission has failed, and since it is a hardware error or a software error, error processing is performed and the processing is terminated (step 405). When the data transmission in the buffer 104 is successfully completed, it is checked whether all the files currently being processed have been transferred, and if there are any unprocessed areas, the processing is repeated from step 402 (step 406). Each user program repeats the above steps as long as there are still files to send (step 4).
07). Thus, each transmission user program 103 uses the fixed-length buffer 104 repeatedly.
Similarly, each receiving user program 203 also uses a fixed-length buffer 204. In the data transfer using the present invention, it is possible to transfer data of any size, but the buffer of the user program needs to be a fixed length, so a fixed-length buffer is prepared and used repeatedly. I have. In the data transfer using the conventional technology, the data is divided and transferred according to the size of the system buffer of the OS regardless of the size of the buffer of the user program. Overhead exists. On the other hand, in the data transfer using the present invention, data transfer is performed in buffer units of the user program, and although division processing or integration processing by the user program still exists, an appropriate size of data in consideration of the scale of data handled by the user program. By using the user buffer, the division processing or the integration processing is only the minimum processing by the user program. Further, in the case of an application such as the file transfer system in the present embodiment, since the file is directly input / output, the data does not need to be divided or integrated at all. Each transmission-side user program 103 includes:
When calling the transmission reception program 106, the start address of the buffer 104 storing the transmission data, the transmission size indicating the size of the file in bytes, and the communication path number for specifying the communication partner are arguments. Pass as The communication path number is a specific transmission side user program 1
03, which is used to identify a combination of a specific receiving user program 203 and a unique numerical value in the system, and corresponds to a connection identifier in TCP / IP. As with TCP / IP, each of two user programs for communication explicitly establishes an end (socket) of a communication path (connection), and a known name (one another is known) at one end. , And the other end requests connection to the named end, and the named end is established by permitting the connection. A communication path identifier (connection identifier) can uniquely identify a pair of two terminations, and a user program can create or use a plurality of communication paths or terminations. A set of programs deals with one communication channel. In the following, the communication path numbers of the three user programs 103 on the transmission side are 1001 and 100, respectively.
2,1003. Also, the communication path numbers of the three user programs 203 on the receiving side, which are the communication partners of the three user programs 103 on the transmitting side, have the same communication path number. Transmission size must be greater than zero.

(A2) Reception of Transmission Request by Transmission Reception Program 106 As shown in the flowchart of FIG. 4, when called, the transmission reception program 106 first creates a new transmission request item 510 (FIG. 5) (step 411). ), And fill the items therein (step 412). As shown in FIG. 5, the transmission request item 510 includes a transmission start address 511 indicating a head address of a buffer holding transmission data in the main storage device 102, a transmission size 512 indicating how much data to transmit. , A transmission path number 513 for specifying the transmission destination, a request source program identifier 514 indicating who transmitted the transmission destination item 510, and a next pointer 515 for linking the transmission request item 510. Transmission start address 511 and transmission size 51 of new transmission request item 510
2 and the communication path number 513 store information given as an argument when called from the user program 103, and the request source program identifier 514 stores the program identifier of the calling user program 103.

Thereafter, the transmission receiving program 106 stores the created transmission request item 510 in the transmission request list 108.
(Step 413). That is, the next pointer 515 of the created transmission request item 510 includes the newest transmission request item 51 in the transmission request list 108.
Stores the starting address of 0. When adding a new transmission request item 510 to the transmission request list 108, each transmission request item 510 in the transmission request list 108 is checked, and the same communication path number 513 is included in the transmission request items 510.
And whether there is a transmission request item 510 having a transmission size 512 of zero. Such a transmission request item 510 is used for a transmission failure report described later, and is deleted from the transmission request list 108 because it has already been used at this point.

Thereafter, the transmission receiving program 106 freezes the currently executing process and pauses until the process is thawed again to wait for a transmission completion report (step 414).
The transmission reception program 106 is called by the user program 103, and during execution, the user program 103
With a program identifier of The pause is described as “the user program 10 calling the transmission reception program 106”.
3 ", when another user program 103 calls the transmission reception program 106 while one user program 103 is suspended, the transmission reception program 106 has the program identifier of the latter user program 103. Works. In the present embodiment, the instruction to restart is performed by the transmission processing program 107 described later.

(A3) Transmission Processing Program 107 (Part 1) Transmission of REQ Command As shown in FIG.
The transmission request list 108 is periodically checked (step 43).
1, 432), if there is a new transmission request item 510, it is taken out and deleted from the transmission request list 108 (step 433). At this time, the transmission request item 510 whose transmission size 512 is zero is ignored because it is a transmission request item for a transmission failure report described later. A REQ command is created for each of the extracted transmission request items 510 and sent to the receiving computer 200 (step 43).
4).

More specifically, the transmission processing program 107
Creates the REQ command block 109 from the plurality of transmission request items in step 434. As shown in FIG. 7A, the REQ command block 109 includes one REQ command for each transmission request item. Each REQ command has a command code 53
1, a transfer size 532, and a communication channel number 533. As a specific example in the present embodiment, three REQs newly issued from three user programs 103 on the transmission side.
The command is transmitted to the transmission processing program 107 in step 4
Assume that it was detected at the time of execution of 31, 432. FIG.
As shown in (a), these three REQ commands are respectively 1001, 10
02, 1003, and 30 as the transfer size 532
Suppose we have 0, 300, 500.

The transmission processing program 107 further writes a transmission instruction in the DMA control list 111 to transmit the REQ command block 109, and activates the communication device 112. As shown in FIG. 7B, the DMA control list 111 is composed of a plurality of entries each corresponding to one transmission / reception instruction, and each entry is a transmission / reception instruction 501 indicating whether it is a transmission instruction or a reception instruction. When the transmission / reception command 501 is a transmission command, it indicates the head address of data to be transmitted on the main storage device 102, or when the transmission / reception command 501 is a reception command, the main storage device for storing data to be received A transmission / reception start address 502 indicating a head address on the PID 102 and a transmission / reception size 503 indicating a size of transmission data or reception data are included. In this case, in order to transmit the REQ command block 109, a transmission instruction is transmitted to the transmission / reception instruction 501 as one entry of the DMA control list 111, and the transmission / reception start address 50
2 is the start address of the REQ command block 109,
The REQ command block 109 is set in the transmission / reception size 503.
The size (fixed length) of each is stored.

(A4) Communication Device 112 (Part 1) (A41) Transmission of REQ Command Block 109 When the communication device 112 is activated, the instruction control circuit 115
Reads the first entry of the DMA control list 111 from the main storage device 102, and in this case, since this entry contains a transmission command, the transmission operation is started. That is, according to the transmission / reception start address 502 and the transmission / reception size 503 included in the first entry, REQ
DMA so that a plurality of REQ commands included in the command block 109 are continuously read from the main storage device 102.
Instruct the circuit 113 to instruct the communication circuit 114 to immediately transmit the read REQ command block 109 to the communication device 212 of the computer 200 via the channel 300. The instruction control circuit 115 controls the DMA control list 1
Eleven subsequent entries respond to any valid instruction, but in this case, DMA control list 111 has no such subsequent valid instruction.

(A42) Notification of completion of transmission When this transmission is completed, the instruction control circuit 115 generates a hardware interrupt and notifies the transmission processing program 107 of the completion of transmission. The transmission processing program 107 confirms the completion of transmission by detecting this interrupt.

(B) Receiving-Side Computer 200 (Part 1) (B1) Receiving-Side User Program 203 (Part 1) Issuance of a Receiving Request In this embodiment, the transmitting-side user program 103
A transmission request is issued to S105, and the user program 203 on the receiving side is configured to issue a reception request to the OS 205. As described later, transmission data from the user program 103 that has issued the transmission request Is transmitted after any one of the destination user programs 203 is ready to receive the data, specifically, after the destination user program 203 issues a reception request for the data. It is transferred to the previous user program.

As shown in the flowchart of FIG. 8, the processing of the receiving-side user program 203 also has a double loop structure similar to the processing of the transmitting-side user program 103, and the file transferred at the beginning and end of the processing. Is secured or released (steps 451 and 458). The outer loop is a loop for processing a plurality of files, and the inner loop is a loop for transferring each file by a plurality of communications.

Each receiving-side user program 203 calls the receiving receiving program 206, notifies the receiving request (step 452), and stores the data stored in the buffer 204 as a part of the file (step 45).
5).

When the reception accepting program 206 is returned from the call, the return value from the call is checked, and if an error is found, error processing is performed and the processing is terminated (step 454). When the output to the file is completed, it is checked whether all the files currently being processed have been transferred, and if there are unprocessed areas, the processing is repeated from step 452 to process them (step 456). Each user program repeats the above steps as long as there are still files to be transmitted (step 457).

(B2) Reception of a reception request by the reception reception program 206 As shown in the flowchart of FIG. 9, when the reception reception program 206 is called, first, a new reception request item 520 is created (step 421). Are filled in (step 422). Receive request item 520
As shown in FIG. 10, a reception start address 521 indicating from which address position the received data is stored in the main storage device 202, a maximum reception size 522 indicating how much data can be received, The communication channel number 523 defined for the set of the original user program and the user program that has issued the reception request, the identifier 524 of the user program of the reception request source, and the next It consists of a pointer 525. The information provided as an argument at the time of calling from the user program of the reception request source is stored in the reception start address 521, the maximum reception size 522, and the communication channel number 523 of the created new reception request item 520, and the request source program identifier 524 Is the receiving user program 2 that is the caller
03 is stored. Note that the maximum reception size 522 must be larger than zero.

The reception reception program 206 adds the created reception request item 520 to the reception request list 208 (step 423). That is, the address of the newest reception request item 520 in the reception request list 208 is stored in the next pointer 525 of the created reception request item 520. Note that a new reception request item 520
Is added to the reception request list 208, each reception request item 520 in the reception request list 208 is examined, and the reception request items 520 having the same communication path number 523 therein and the maximum reception size 522 being zero are checked. Request Item 52
Check whether 0 exists. Such a reception request item 520 is used for reporting a reception failure described later, and has already been used at this time, so that the reception request list 208
Remove from.

Thereafter, similarly to the transmission reception program 106, the reception reception program 206 freezes the process currently being executed and pauses until the process is defrosted again to wait for a reception completion report (step 424). In the present embodiment,
The restart instruction is received by the reception processing program 207 described below.
Do.

(B3) Reception Processing Program 207 (Part 1) REQ Command Block Reception Command The reception-side computer 200 is prepared to receive the REQ command block transmitted from the transmission-side computer 100 at any time. There is a need. The reception processing program 207 transmits the command block to the communication device 2.
Command 12

That is, as shown in the flowchart of FIG. 11, the reception processing program 207 receives the REQ command block, and issues a reception command instructing to store the REQ command block in the main storage device 202 as the REQ command block 209 to the DMA control list 211. Is written, and the communication device 112 is activated, and waits for completion of reception (step 441).

As shown in FIG. 12B, the DMA control list 211 has the same structure as the DMA control list 111. The reception processing program 207 receives the REQ command block 109 and
To be stored as the main storage device 202 as a DMA
One entry of the control list 211 includes a transmission / reception instruction 50
No. 4, a reception command, a start address of the REQ command block 209 as the transmission / reception start address 505, and a size (fixed length) of the REQ command block 209 as the transmission / reception size 506 are stored.

(B4) Communication Device 212 (Part 1) (B41) Reception of REQ Command Block 109 When the communication device 212 is started, the command control circuit 215 interprets and executes the DMA control command. First, the instruction control circuit 215 reads the first entry of the DMA control list 211 from the main storage device 202, and controls the communication circuit 214 and the DMA circuit 213 according to the instruction in this entry, in this case, the reception instruction. That is, the communication circuit 2
When the communication circuit 214 receives the contents of the REQ command block 109 from the computer 100 via the channel 300, the DMA circuit 213 sends the contents of the received REQ command block 109 to the DMA circuit 213. The REQ command block 209 on the main memory 202 is immediately written. That is,
The received REQ command block 109 is written as the REQ command block 209 to the main storage device 202 in accordance with the transmission / reception start address 505 and the transmission / reception size 506 included in the read entry. In FIG. 7B,
REQ command block 2 including three transmission requests REQ
09 is shown. The DMA circuit 213 responds to a valid instruction in a subsequent entry of the DMA control list 211, but in this case, the DMA control list 21
1 There is no such subsequent valid instruction.

(B42) Reception completion notification The instruction control circuit 215 generates a hardware interrupt upon completion of this writing, and
To the reception completion. The reception processing program 107 confirms the reception completion by detecting this interruption, and proceeds to the next step 441.

(B5) Reception Processing Program 207 (Part 2) (B51) Transmission Command of ACK / NACK Command When the reception of the REQ command block 209 is completed, the reception processing program 207 executes In response to the REQ command,
Check whether reception is possible or not, create an ACK command or a NACK command, and
The CK command block is sent to the sending computer 100 (step 442).

That is, in order to check whether or not each REQ command can be received, each R in the REQ command block 209 is read from the reception request list 208.
A reception request item 520 having the same channel number 523 as the channel number 533 for the EQ command is searched. If the corresponding reception request item 520 does not exist, the RE
The Q command cannot be received. That is, if the reception request specifying the communication channel number 533 has not been issued by any of the user programs 203 on the receiving side at the time when the reception of the REQ command block 209 is completed, the REQ command is not received. It becomes possible. If the corresponding reception request item 520 exists,
Further, it is determined whether the transfer size 532 for the REQ command is not larger than the maximum reception size 522 of the corresponding reception request item 520. Its transfer size 5
32 exceeds its maximum receive size 522, then its R
The EQ command cannot be received, but otherwise the REQ command can be received. In step 442, the reception request item 520 having the maximum reception size 522 of zero is ignored since it is a reception request item for a reception failure report described later. There are two types of unreceivable REQ commands. If the corresponding reception request has not yet occurred, the REQ command has been reported too early because the REQ command was notified too early. If it exceeds, an unexpected situation such as a program error occurs, and the transmission request and the reception request are notified as failure to the respective user programs (in this case, the reception request has already occurred).

In the present embodiment, as a specific example, three user programs 103 on the transmitting side are used in FIG.
After the three REQ commands illustrated in (a) are issued, by the time when the reception of the REQ command block 209 is completed, a reception request corresponding to two of these three REQ commands is transmitted to the reception side. User programs 2
03, and the transfer size 532 specified by each of these two REQ commands does not exceed the maximum receive size specified by their corresponding receive request. Further, the third R of the three REQ commands is
The reception request corresponding to the EQ command is issued with a delay from another user program on the reception side.
REQ command does not exceed the maximum reception size specified by the corresponding third reception request. In this case, when the reception of the REQ command block 209 is completed, the first two REs
The Q command can be received, and the last REQ command cannot be received.

An ACK command and a NACK command are generated for the REQ command determined to be receivable and the REQ command determined to be unreceivable, and sent to the computer 100 as an ACK command block 210. As shown in FIG. 12A, the ACK command block 210 includes the REQ command block 20.
9, the REQ command in the command section 531 in the REQ command block 209 is simply changed to “ACK” for the REQ command determined to be receivable.
K command is included. Further, for the REQ command determined to be unreceivable in the REQ command block 209, the REQ in the command section 531 in the REQ command block 209 is changed to “NACK”, and the cause of the unreception is detected. If the transfer size is exceeded, the transfer size 532 is changed to a receivable size. By checking whether or not the transfer size 532 has been changed, the computer on the transmitting side can determine whether the reason for reception failure is due to unprepared reception or due to excessive size (fatal error).

In the example of FIG. 12A, the ACK command block 210 includes two ACK commands and one NAC
It consists of K commands. That is, the communication path number is 1001
And the REQ command 1002 are receivable and ACK because the corresponding reception request has already occurred and the requested transfer size does not exceed the receivable amount.
Command is returned. On the other hand, the REQ command having the communication channel number of 1003 cannot be received because the corresponding reception request has not been generated, and the NACK command is returned. Since the cause of the reception failure is not the transfer size excess but the reception request not occurring, the transfer size 532 of the NACK command is not changed.

The reception processing program 207 generates the generated A
An instruction to transmit the CK command block 210 to the computer 100 is issued. The instruction is R
This is the same as the transmission of the EQ command block 109. That is, the reception processing program 207 includes a transmission command as the transmission / reception command 504 and an ACK command block 2 as the transmission / reception start address 505 in the DMA control list 211.
10 as the transmission / reception size 506
A transmission command having the size (fixed length) of the K command block 210 is stored, and the communication device 212 is started. After that, in order to confirm the transmission completion, the communication device 21
Wait for a hardware interrupt from 2.

(B52) Reception failure report Although not generated in the above hypothetical example, a reception request having a communication path number matching a certain REQ command has already been issued from any user program on the reception side. However, if the transfer size specified by the REQ command exceeds the maximum reception size specified by the reception request, the reception processing program 207 reports the reception failure to the reception-side user program 203 that has issued the reception request. That is, the reception processing program 207 sets the maximum reception size 52 of the reception request item 520 that has failed to be received.
2 is changed to zero, the changed reception request item 520 is returned to the reception request list 208, and the reception-side user program 203 waiting for reception completion specified by the request source program identifier 524 of the reception request item 520 is restarted. (Step 444 (FIG. 11)).

When the reception accepting program 206 resumes the process (as a call extension process of the user program 203), its own program identifier (in this case, the calling user program 20) is displayed in the reception request list 208.
Request item 52 having a program identifier of (3)
It checks whether 0 exists and returns to the receiving user program 203. As a return value, a return value indicating failure is used if a reception request is returned, and a return value indicating success is used otherwise (step 425 (FIG. 9)).

(B6) User Program 203 (Part 2) When the reception receiving program 206 ends, the process returns to the calling user program 203. The user program 203 checks the return value of the result of the call (step 4).
53 (FIG. 8)), if an error occurs, error processing is performed and the processing is terminated (step 454 (FIG. 8)).

In the above hypothetical example, the call was successful and no error handling occurred.

(C) Transmission-side Computer (Part 2) (C1) Transmission Processing Program 107 (Part 2) ACK Command Block Reception Command The transmission-side computer 100 prepares to receive the ACK / NACK command block 210. That is, as shown in step 435 of FIG.
7 writes an ACK command block reception command in the DMA control list 111, activates the communication device 112, and waits for reception completion. This instruction receives the ACK command block and stores the ACK command block 1 in the main storage device 102.
Requires writing as 10. Specifically, the transmission processing program 107 stores the DMA control list 111
The reception command is sent to the transmission / reception command 501, and the transmission / reception start address 5
02 is the start address of the ACK command block 110, and the transmission / reception size 503 is the ACK command block 1
10 (fixed length) are stored. Confirmation of reception completion is performed by waiting for an interrupt from the communication device 112.

(C2) Communication Device 112 The communication device 112 receives the ACK command block 210 in response to the reception command, and stores the ACK command block 210 in the main storage device 102.
Write as CK command block 110. The operation of this circuit at this time is the same as when the communication device 212 receives the REQ command block.

(C3) Transmission Processing Program 107 (Part 3) Data Transmission Instruction Upon receiving the ACK command block, the computer 100 on the transmission side starts data transmission. That is, the transmission processing program 107 determines in step 436 in FIG.
Multiple ACKs included in ACK command block 110
Each command is taken out, and the transmission of the corresponding transmission data is instructed to the communication device 112, which is activated, and waits for the completion of the transmission of the data. The transmission data for each ACK command is searched from the transmission request list 108 for a transmission request item 510 having the same communication path number as the ACK command, and specified by the transmission start address 511 and the transmission size 512 in the transmission request item 510. . That is, the transmission processing program 107
The transmission command is stored in the transmission / reception command 501 in the A control list 111, the retrieved transmission start address 511 is stored in the transmission / reception start address 502, and the retrieved transmission size 512 is stored in the transmission / reception size 503.
The communication device 112 is instructed to transmit data in response to the CK command.

When there are a plurality of ACK commands in the ACK command block 110, the transmission processing program 107 stores a plurality of transmission commands corresponding to the ACK commands in the DMA control list 111. The order in which these transmission instructions are stored in the DMA control list 111 is the same as the order of the corresponding ACK commands stored in the received ACK command block 110.

If there is a NACK command in the received ACK command block 110, the transmission processing program 107
One of the following processes is performed. That is, each NAC
The value of the transfer size 532 in the K command is
The transmission size requested by the Q command, that is, its RE
If the transmission size is equal to the transmission size 512 in the transmission request item 510 corresponding to the Q command, the cause of the reception failure is that a reception request has not yet been generated in the receiving computer 200. Therefore, the transmission processing program 107 returns the transmission request item 510 to the transmission request list 108 in order to retransmit the REQ command.

On the other hand, if the transfer size 532 in the NACK command is smaller than the transmission size requested by the corresponding REQ command, the cause of the reception failure is that the transmission size requested by the corresponding REQ command is This is because the reception request generated by the computer 200 exceeds the specified maximum reception size. In this case, the transmission processing program 107 reports the transmission failure to the transmission-side user program 103. That is, the transmission processing program 107
Restarts the processing of the transmission-side user program 103 waiting for the transmission completion specified by the request source program identifier 514 of the failed transmission request item 510. At this time, the transmission size 512 of the failed transmission request item 510 is changed to zero, and the transmission request item 510 is returned to the transmission request list 108.

(C4) Communication Device 112 (Part 3) Data Transmission When the communication device 112 is started, the transmission processing program 1
The transmission of the data instructed by 07 is performed based on the DMA control list 111. That is, the DMA circuit 113
The DMA circuit 113 reads out the transmission data specified by each transmission command described in the DMA control list 111 from the buffer 104 in the user program 103, transmits the transmission data, and the communication circuit 114 interrupts when the transmission is completed. To the transmission processing program 107. When a plurality of data transmission instructions are described in the DMA control list 111, the instruction control circuit 115 sequentially reads out a plurality of transmission data specified by the transmission instructions according to the description order of the instructions, and the communication circuit 114 Are sequentially transmitted. As described above, on the transmission side, the transmission data is transmitted without being copied from the buffer of the user program 103 to the OS 105. The transmission data in the user program 103 is continuously transmitted without being divided. In the case of the present example, two data are transmitted, and when the two transmissions are completed, a hardware interrupt is generated.

(C5) Transmission Completion Report When the transmission processing program 107 is notified of the completion of the data transmission from the communication device 112, it reports the transmission completion to the transmission-side user program 103 (step 437 (FIG. 6)). After transmitting the ACK command block 209 shown in FIG. 12A, the transmission completion is reported to the two user programs 203 corresponding to the two ACK commands. At this time, unlike the transmission failure report, the corresponding transmission request item 510 is not returned to the transmission request list 108.

(C6) User Program 103 (Part 2) Processing for Transmission Failure When the transmission-side user program 103 returns from the call of the transmission reception program 106, it checks the return value (step 404 (FIG. 3)). If an error occurs, error processing is performed (step 405 (FIG. 3)).

(D) Receiving Computer 200 (Part 2) (D1) Receiving Processing Program 207 (Part 3) Data Receiving Command The receiving processing program 207 issues an ACK command block transmission command, and then executes ACK by the ACK command block. If at least one command has been returned (step 443 (FIG. 9)), the communication device 212 is instructed to transmit a data transmission command corresponding to the ACK command, the communication device 212 is activated, and the transmission is completed. Wait (Step 4
44 (FIG. 9)). The data to be received in response to the ACK command includes the reception request item 520 having the communication path number included in the ACK command as the reception request list 208.
, And the data specified by the reception start address 521 in the reception request item 520. Therefore, the transmission processing program 107 sets the reception command code in the transmission / reception command code 504 in the DMA control list 211 and the reception start address 52 searched for in the transmission / reception start address 505.
By storing the transfer size 532 specified by the ACK command returned in the transmission / reception size 506 in the transmission / reception size 506, the communication device 212 is instructed to receive data corresponding to the ACK command. The ACK command block 21
If a plurality of ACK commands are stored in 0,
According to the order of the ACK commands, the corresponding data reception commands are stored in the DMA control list 211.

When the transmission processing program 107 determines that no ACK command has been returned by the transmitted ACK command block 210 as a result of the determination at step 443, the transmission processing program 107 proceeds to step 441 without issuing a data reception instruction. Return and issue an instruction to receive the REQ command block again.

(D2) Communication Device 211 (Part 3) (D21) Data Reception When the communication device 212 is started, the reception processing program 2
07 is received on the basis of the DMA control list 211. That is, the instruction control circuit 215
Is any one of the user programs specified by the reception instruction included in the read entry when the head entry of the DMA control list 211 is read from the main storage device 202 and the communication circuit 214 receives the data from the transmitting computer 100. The received data is written to a buffer 104 in 103. When a plurality of data reception instructions are described in the DMA control list 211, the instruction control circuit 2
15 sequentially writes a plurality of data sequentially received in the buffers 204 in the plurality of user programs 203 specified by the reception instructions in accordance with the description order of the instructions. After transmitting the ACK command block shown in FIG. 12A, two data corresponding to two ACK commands are received. In this way, even on the receiving side, the data received by the communication device 214 is not copied to the buffer in the OS 205 as in the related art, but is directly stored in the buffer 204 of any user program 203.
Is written to.

(D22) Notification of Reception Completion When the writing of any reception data is completed, the instruction control circuit 215 generates a hardware interrupt and notifies the reception processing program 207 of the completion of data reception.
The reception processing program 107 confirms the reception completion by detecting this interruption, and proceeds to the next step 445. When a plurality of data reception instructions are described in the DMA control list 211, the reception completion interrupt is generated each time a plurality of data specified by the instructions are written to any of the buffers 203.

(D3) Reception Processing Program 207 (No. 4) (D31) Reception Completion Report When the communication device 211 notifies the completion of data reception, the reception processing program 207 responds to the ACK command corresponding to the received data. A report of the completion of reception is made to the user program 203 of the reception request source (step 44)
5 (FIG. 9)). After transmitting the ACK command block shown in FIG. 12A, the reception completion is reported to the two user programs 204 for the two ACK commands. At this time, the corresponding reception request item 510 is not returned to the reception request list 108.

(D32) Receiving-side user program 203 When the receiving-side user program 203 returns from calling the reception receiving program 206, it checks the return value. If unsuccessful, it will return at the time the ACK command block 210 is created, and at this point in the example, it will always return successfully. Upon returning, the received data is output to a part of the file in the buffer 204 (step 455 (FIG. 8)). When the output is completed, it is checked whether all the files currently being processed have been transferred and the unprocessed area is checked. If there are, repeat from step 452 to process them (step 456). Each user program repeats the above steps as long as there are still files to be transmitted (step 457).

(E) Transfer of Data in Response to NACK Command In the hypothetical example considered here, for a transmission request item 510 having a communication path number of 1003, a corresponding reception request is output by the receiving computer 200. The NACK command was returned from there because it was not done. Therefore, the transmission data for the transmission request item 510 is not transmitted, but this data is transmitted thereafter as follows.

As shown in FIG. 8, the transmission processing program 1
07 issues the above-mentioned transmission command in response to the received ACK command, and then moves to step 432 to search for a new transmission request. The transmission request item 510 to which the data has not been transmitted is returned to the transmission request list 108 by the transmission processing program 107. Therefore, when the transmission processing program 107 searches for a new transmission request, the transmission request item 510 is searched, and the REQ including the corresponding REQ command by the method described above.
The command block is sent to the computer 200. At this time, if the receiving computer 200 has already issued a receiving request with the communication path number of 1003, the receiving computer 200 sends an ACK to this REQ command.
The ACK command block including the command is returned by the method described above, and thereafter, transmission data for this REQ command is transmitted from the computer 100, and
00 received. In this way, transmission data that has failed to transmit earlier can also be transmitted.

As described above, according to the present embodiment, since data copy processing between the buffer of the user program and the buffer of the OS is not required in either the transmitting computer or the receiving computer, data transfer between computers is not required. Can be performed at high speed.

In the conventional data transfer by TCP / IP, data is transmitted even if the receiving user program is not ready. In such a case, it is necessary for the receiving computer to temporarily store the received data in the OS buffer and then copy the data to the buffer of the receiving user program, and the overhead of this data copying process has prevented the realization of high-speed data transfer. . Also, if there are too many user programs on the receiving side that are not ready for reception, the OS buffer overflows and data must be retransmitted. In preparation for this retransmission, the sending computer also needs to temporarily store data in the OS buffer. was there. For this reason, data copying occurs in the computer on the transmission side, and its overhead has hindered realization of high-speed data transfer.

However, in the data transfer according to the present embodiment, the completion of reception preparation is confirmed by exchanging commands prior to data transfer, and when reception preparation is not completed, only the command, not the data itself, is retransmitted. This eliminates the need for conventional data copying.

In this embodiment, even when transferring large data exceeding the size of the fixed-length communication buffer of the OS, it is not necessary to divide and transfer the data. Data transfer can be performed at high speed.

In conventional data transfer by TCP / IP, there is no means for adjusting the size of data to be transmitted and received in advance, so the transfer size needs to be a fixed value set by the OS. Therefore, when transferring large data exceeding this, it is necessary to divide the data for each transfer size in the OS on the transmitting side and reconstruct the received data in the OS on the receiving side. High-speed data transfer cannot be realized due to the overhead of the data division and reconstruction processing.

However, in the data transfer according to the present embodiment, data of an arbitrary size can be transferred by arbitrating the size of data to be transmitted and received in advance.
Integration processing is not required, and high-speed data transfer can be realized. Similarly, by arbitrating the number of data to be transferred by the communication device in advance, communication of a plurality of data transfers can be collectively processed, so that start-up processing and post-processing (interrupt processing) of the communication device are reduced, and higher speed is achieved. Data transfer is feasible.

In the data transfer by the conventional HDLC, the data transfer is arbitrated prior to the data transfer as in the present invention, so that there is no data copy overhead.
However, there is a drawback that the OS does not intervene in the data transfer, and the user program performing the transfer monopolizes the communication device, and a plurality of user programs cannot simultaneously perform the data transfer.

However, in the data transfer according to the present embodiment, since the arbitration work is performed by the OS collectively, arbitration of a plurality of data transfers is simultaneously performed without contradiction while maintaining the advantage that there is no data copy overhead. be able to.

<Modifications> The present invention is not limited to the above embodiment, but can be implemented in various forms. For example, (1) In the embodiment of the invention described above, a system in which only two computers are connected, but a system in which more computers are connected to each other may be used. In this case, it is desirable that transmission paths corresponding to different computer pairs are provided for each computer pair, and that each computer pair is connected by the corresponding transmission path.

(2) The transmission path connecting the computers is not limited to the channel described in the embodiment, but may be, for example, an interconnect network connecting a plurality of computers. For example, a crossbar switch, a hyper crossbar switch, or a multistage switch network may be used.

(3) The data transfer between these computers may be a data transfer in the form of a packet. For example, data is usually transferred in the form of a packet between a plurality of computers connected by the hyper crossbar network. Each packet contains an address for specifying the computer at the transfer destination, data to be transferred, and the like. The present invention can also be applied to a system for transferring data between computers in such a format.

(4) In the embodiment, the input / output interface between the user program and the OS is a synchronous type, that is, the user program is of a type which waits until the input / output processing requested to the OS is completed. An asynchronous input / output interface may be used. In order for the file transfer system shown in the embodiment to be a file transfer system having an asynchronous input / output interface, the transmission / reception receiving program immediately returns control to the user program without waiting for the completion of the transmission / reception, and the user program transmits / receives the transmission / reception. After issuing the request, a request to wait for the completion of transmission / reception is issued again to the reception program, and the reception program may receive the request and perform the remaining processing.

[0085]

As is apparent from the above description, according to the present invention, there is no data copy process between the buffer of the user program and the buffer of the OS, so that data transfer between computers can be performed at high speed.

Furthermore, even when transferring large data, it is not necessary to divide and transfer the data, so that the overhead of the communication processing can be reduced and the data transfer can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a computer system that implements a data transfer method according to the present invention.

FIG. 2 is a time chart of data transfer in the device of FIG. 1;

FIG. 3 is a flowchart of a transmission-side user program (103) used in the apparatus of FIG. 1;

FIG. 4 is a transmission reception program (1) used in the apparatus of FIG.
06) Flow chart.

FIG. 5 is a transmission request list (10) used for the device of FIG. 1;
The figure which shows the data structure of 8).

FIG. 6 shows a transmission processing program (1) used in the apparatus shown in FIG.
07).

FIG. 7A is a diagram showing a data structure of a REQ command block (109) used in the apparatus shown in FIG. 1; (B)
Is the DMA control list (111) used for the device of FIG.
The figure which shows the data structure of FIG.

FIG. 8 is a flowchart of a receiving-side user program (203) used in the apparatus of FIG. 1;

9 is a reception reception program (2) used in the apparatus of FIG.
06) Flow chart.

FIG. 10 shows a reception request list (20
The figure which shows the data structure of 8).

FIG. 11 is a flowchart of a reception processing program (207) used in the apparatus of FIG. 1;

FIG. 12A is a diagram showing a data structure of an ACK command block (210) used in the apparatus shown in FIG. 1; (B)
Is the DMA control list (211) used for the device of FIG.
The figure which shows the data structure of FIG.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Shimizu 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Toyohiko Kagimasa 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Inside the Central Research Laboratory

Claims (9)

[Claims] (A) A data stored in a first area for a source user program on a main storage device of the first computer by a source user program of the first computer, A transmission request for requesting transmission to a user program of a transmission destination of a second computer connected to the first computer via a transmission path is issued to a first OS controlling the first computer, (B) in response to the transmission request, from the first OS to a second OS controlling the second computer;
Inquires whether the destination user program is in a data receivable state. (C) In response to the inquiry, the second OS is in a state in which the destination user program is in a data receivable state. Is determined, and the result of the inquiry indicating the result of the determination is transmitted by the second OS to the first OS.
S, and (d) receiving the data specified by the transmission request by the second OS when the second OS determines that the destination user program is in a state capable of receiving data. And instructing the communication device of the second computer to write the data into the second area for the user program of the transmission destination defined on the main storage device of the second computer, and (e) And (f) when the inquiry result indicates that the user program of the transmission destination is in a data receivable state, the first OS instructs the communication device of the first computer to transmit the data, and (f) In response to the instruction from the first OS, the communication device of the first computer reads the data from the first area and transfers the data to the second computer via the transmission path, g) in response to the indication by the second OS, the second OS By the communication device calculated machine, it receives the data, the data transfer method comprising the step of writing to the area of the second. 2. The method according to claim 1, further comprising the step of: repeating the step (b) by the first OS when the inquiry result indicates that the user program of the transmission destination cannot receive data. 2. The data transfer method according to 1. 3. The method according to claim 1, further comprising the step of requesting the second OS to receive a request for receiving the data from the user program of the transmission destination, wherein the step (c) comprises: 3. The method according to claim 1, further comprising: determining whether the user program of the transmission destination is in a receivable state according to whether the data reception request has already been issued from the user program. Data transfer method. 4. The transmission request specifies the size of the data, the reception request specifies the size of the area for the destination user program, and the step (c) receives the inquiry. At this point, when a request to receive the data has already been issued from the user program of the transmission destination, it is further determined whether or not the size of the data does not exceed the size of the second area. At the time of reception, even if a request for receiving the data has already been issued from the user program of the transmission destination, if the size of the data exceeds the size of the second area, the user program of the transmission destination 4. The data transfer method according to claim 3, further comprising the step of determining that the data is in a non-receivable state. 5. The step (a) is such that a plurality of transmission requests are issued by the plurality of transmission source user programs to a plurality of transmission destination user programs running on the second computer. Executed by each of the plurality of transmission source user programs being executed by the first computer, and the step (b) is performed by the plurality of transmission destination user programs specified by the plurality of transmission requests. It is determined from the first OS whether the second OS is enabled or not.
S, and in the step (c), the second OS determines whether or not each of the plurality of destination user programs is in a state capable of receiving data. The second OS collectively notifies the first OS of a plurality of inquiry results indicating the determination result for the destination user program. The step (d) is performed by the second OS. When it is determined that some of the plurality of destination user programs among the plurality of destination user programs are in a state in which data can be received, a plurality of user programs corresponding to the plurality of destination user programs are determined. The part of the plurality of data specified by the transmission request is transferred to the part of the plurality of destination user programs defined on the main storage device of the second computer. Collectively instructing the communication device of the second computer to write to each area, and the step (e) is performed by the first OS by the first OS in response to the plurality of inquiry results. Instructing the communication device of the first computer to collectively instruct the communication device of the first computer to transmit some of the plurality of data designated by the user programs of the plurality of transmission sources held on the main storage device of one computer. The step (f) includes the step of, in response to the instruction by the first OS, transmitting the part of the plurality of data by the communication device of the first computer to the first computer. Sequentially reading from the main storage device and sequentially transferring the data to the second computer via the transmission line. The step (g) is performed by the communication device of the second computer. Receiving data sequentially, and 2. The data transfer method according to claim 1, further comprising the step of writing to the plurality of areas on the main storage device of the second computer. 6. The first OS causes the at least one other user program to indicate that at least one of the other user programs is in a state where data cannot be received by the first OS. 6. The data transfer method according to claim 5, further comprising the step of repeating the step (b) for a transmission request issued by the transmission source user program. 7. The data transfer method according to claim 5, wherein said step (b) is repeatedly executed at a fixed time interval. 8. The method according to claim 1, further comprising the step of requesting the second OS to receive a data reception request from each of the plurality of destination user programs, wherein the step (c) comprises: Determining whether or not the destination user program is in a receivable state according to whether or not a data reception request has already been issued from each of the plurality of destination user programs. Item 7. The data transfer method according to item 5 or 6. 9. The plurality of transmission requests each specify a size of data to be transmitted, and each of the reception requests issues the reception request formed on the main storage device of the second computer. The size of the area for the destination user program is specified. In the step (c), when the inquiry is received, a data reception request has already been issued from the destination user program requested by each transmission request. It is further determined whether or not the size of the data specified by the transmission request does not exceed the size of the area for the destination program specified by the reception request. Even when a request to receive data has already been issued from the user program of the transmission destination specified by the request, the size of the data specified by the transmission request is equal to the size of the transmission destination 9. The data transfer method according to claim 8, further comprising a step of determining that the destination user program is in an unreceivable state when the size of the area exceeds the size of the user program area.