JP2014052786A - Computer, computer system and shared memory control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a computer system which can share a memory without using dedicated hardware and has high economical efficiency.SOLUTION: A computer system includes: a first computer including a first operation unit, a first bus bridge connected to the first operation unit, a first storage unit connected to the first bus bridge or the first operation unit to store data including shared data, and a first communication control unit connected to the first bus bridge; and a second computer including a second operation unit, a second bus bridge connected to the second operation unit, a second storage unit connected to the second bus bridge or the second operation unit to store data including shared data, and a second communication control unit connected to the second bus bridge and the first communication control unit. The first computer transmits a change data packet including change data for changing the shared data, and identification information for designating a computer having transmission right to the second computer when designated to have the transmission right by the identification information.

Description

  The present invention relates to a computer, a computer system, and a shared memory control method, and more particularly to a computer, a computer system, and a shared memory control method that share a memory using data communication.

  In a computer system including a plurality of computers, a plurality of computers may share data by performing data communication between shared memories that are individually held. In such a shared memory control method, when there is a change in the data in the shared memory held by a certain computer, data communication is performed between the computers in order to reflect the changed data in the shared memory of another computer. As a method for realizing control of the shared memory using data communication, there is a method using a dedicated shared memory controller.

  FIG. 4 is a block diagram illustrating a configuration example of a computer system that includes a plurality of computers and shares data among the computers. This computer system includes a shared memory controller, which is dedicated hardware, and shares data by performing data communication between independent shared memories for each computer. The computer system can operate in real time with a period of several milliseconds. For a computer system that includes a plurality of computers and operates in real time, a shared memory control method using data communication between shared memories is an excellent method because it can simplify complicated data communication between computers.

  The computer system 300 of FIG. 4 includes four computers, a shared memory controller dedicated to each computer, and an independent shared memory. With reference to FIG. 4, an outline of a memory sharing method in the computer system 300 will be described.

  The computer system 300 includes computers 310, 320, 330, and 340. IDs (Identification Data) that are identification information of the computers 310, 320, 330, and 340 are “1”, “2”, “3”, and “4”, respectively.

  The computer 310 includes a CPU 311, a bus bridge 312, a memory 313, a shared memory controller 314, and a shared memory 315. The computer 320 includes a CPU 321, a bus bridge 322, a memory 323, a shared memory controller 324, and a shared memory 325. The computer 330 includes a CPU 331, a bus bridge 332, a memory 333, a shared memory controller 334, and a shared memory 335. The computer 340 includes a CPU 341, a bus bridge 342, a memory 343, a shared memory controller 344, and a shared memory 345. As described above, the computers 310, 320, 330, and 340 include independent shared memories 315, 325, 335, and 345, respectively.

  Next, the operation of the memory sharing method of the computer system 300 will be described by taking as an example a case where an application program executed by the CPU 311 of the computer 310 changes data in the shared memory 315.

  First, the CPU 311 sends, via the bus bridge 312, to the shared memory controller 314, a change address that is an address where the data in the shared memories 315, 325, 335, and 345 should be changed, and change data that is changed data. Forward. The shared memory controller 314 transfers the packet including the changed address and the changed data of the shared memory 315 to the shared memory controller 324 of the computer 320 and changes the changed address data of the shared memory 315 to changed data.

  The packet transmitted from the shared memory controller 314 is received by the shared memory controller 324. The shared memory controller 324 transfers the packet including the changed address and the changed data to the shared memory controller 334 of the computer 330 and changes the changed address data in the shared memory 325 to the changed data.

  The packet transmitted from the shared memory controller 324 is received by the shared memory controller 334. The shared memory controller 334 transfers the packet including the changed address and the changed data to the shared memory controller 344 of the computer 340 and changes the changed address data in the shared memory 335 to the changed data.

  The packet transmitted from the shared memory controller 334 is received by the shared memory controller 344. The shared memory controller 344 transfers the changed address and the changed data packet to the shared memory controller 314 of the computer 310 and changes the changed address data in the shared memory 345 to changed data.

  The packet transmitted from the shared memory controller 344 is received by the shared memory controller 314. The shared memory controller 314 discards the received packet, that is, the packet transmitted by itself.

  Through the operation as described above, the computer system 300 shares data between the computers 310, 320, 330, and 340.

  A technique in which a plurality of devices share data by performing data communication between shared memories is also described in Patent Documents 1 and 2, for example.

JP 09-270798 A (page 8, FIG. 1) JP 07-152640 A (page 5-6, FIG. 3)

The data sharing method of the computer system 300 requires a dedicated shared memory controller and an independent shared memory. Therefore, there is a problem that the cost of hardware necessary for data communication for sharing data increases as the number of computers increases.
(Object of invention)
The present invention has been made in view of the technical problems as described above, and provides a computer, a computer system, and a shared memory control method that can share a memory without using dedicated hardware and are highly economical. The purpose is to do.

  The computer system of the present invention includes a first arithmetic unit, a first bus bridge connected to the first arithmetic unit, and shared data connected to the first bus bridge or the first arithmetic unit. A first storage unit for holding data, a first computer including a first communication control unit connected to the first bus bridge, a second arithmetic unit, and a second arithmetic unit A second bus bridge, a second storage unit connected to the second bus bridge or the second arithmetic unit and holding data including shared data; a second bus bridge and a first communication control unit; A second computer including a second communication control unit connected to the first computer, the first computer including change data for changing the shared data, and change data including identification information designating a computer having a transmission right The packet is specified to have transmission rights by the identification information. And transmitting to the second computer.

  The computer according to the present invention includes a first arithmetic unit, a first bus bridge connected to the first arithmetic unit, and data including shared data connected to the first bus bridge or the first arithmetic unit. And a first computer including a first communication control unit connected to the first bus bridge, a computer having change data for changing shared data and a transmission right A change data packet including identification information designating the second data when the identification information designates having a transmission right, and a second bus bridge connected to the second calculation unit, A second storage unit connected to the second bus bridge or the second arithmetic unit and holding data including shared data; a second bus unit connected to the second bus bridge and the first communication control unit; To the second computer including the communication control unit And features.

  According to the shared memory control method of the present invention, from a first computer including a first storage unit that holds data including shared data to a second computer including a second storage unit that stores data including shared data. A change data packet including change data for changing shared data and identification information designating a computer having a transmission right is transmitted when the first computer has a transmission right.

  The computer, computer system, and shared memory control method of the present invention do not require dedicated hardware, and can realize a memory sharing function only with software that operates on a general-purpose computer. Therefore, there is an effect that the economy is high.

It is a block diagram which shows the structure of the computer system of the 1st Embodiment of this invention. It is a figure which shows the structure of the data of the packet transmitted / received in the computer system of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the computer system of the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the computer system of the background art of this invention.

  First, the basic principle of the present invention will be described.

  The computer system of the present invention reflects the changed data in the shared memory of each computer reliably and quickly when there is a change in the shared memory held by each computer in data communication between a plurality of computers. This control ensures the reliability and secrecy of data communication between computers.

  Specifically, the operation is as follows. First, the order of computers that transmit and receive packets is determined in advance among a plurality of computers. Identification of a computer for defining the order uses an ID or the like assigned to each computer.

  When a computer that requested the change changes the data in the shared memory shared with other computers, the address of the shared memory to be changed and the packet containing the changed data are sent to the computer in the next order. To do. The computer that has received the packet transmits the packet to the next computer in the next order, and changes the data at the designated address in the shared memory based on the contents of the received packet.

  If the next destination transmission destination computer is the change request source computer, the computer that received the packet discards the packet and does not transmit it to the change request source computer.

  In a computer system composed of a plurality of computers, when changing data in the shared memory, it is necessary to synchronize the computers. There is a possibility that there is a computer that has received a packet containing the change of the shared memory at a certain moment, and a computer in which the shared memory has been rewritten, and a computer that has not yet received the packet and has not rewritten the shared memory. is there.

  Therefore, in the present invention, the ID of a single computer having the transmission right is included in the packet, and the right to rewrite the shared memory is transferred on a computer basis. In this way, by transferring the transmission right, synchronization between a plurality of computers using the shared memory is achieved, and a plurality of computers are prevented from simultaneously rewriting data at the same address in the shared memory.

  A communication hub may be used for communication between computers. At that time, if a communication hub such as an Ethernet (registered trademark) hub or a USB hub fails, the communication path may be automatically switched. By using a communication path that is operating normally, data communication using the shared memory can be continued even if a communication line break or a communication hub failure occurs, thereby achieving reliability.

  Alternatively, communication lines between computers may be multiplexed without using a communication hub for communication between computers. By duplicating the communication line, data communication using the shared memory can be continued even if the communication line is disconnected or the communication controller is broken, so that reliability is realized.

In the shared memory control method using communication, only a part of the memory is originally transmitted as a packet. For this reason, it is difficult to determine communication contents even if a packet is intercepted. Further, when an encryption code is added to a packet and a base address and data are transmitted, the order in which the data is arranged may be randomly changed. Such encryption can further enhance the confidentiality of communication data.
(First embodiment)
An overview of a computer system including a shared memory according to the first embodiment of this invention will be described with reference to the drawings.
(Configuration of the first embodiment)
FIG. 1 is a block diagram showing a configuration of a computer system according to the first embodiment of this invention. The computer system of this embodiment is an example in the case of including four computers.

  The computer system 100 of this embodiment includes four computers 110, 120, 130, and 140, a first communication hub 151, and a second communication hub 152. The IDs of the computers 110, 120, 130, and 140 are “1”, “2”, “3”, and “4”, respectively.

  The computer 110 includes a CPU 111, a bus bridge 112, a memory 113, and a communication controller 114. The computer 120 includes a CPU 121, a bus bridge 122, a memory 123, and a communication controller 124. The computer 130 includes a CPU 131, a bus bridge 132, a memory 133, and a communication controller 134. The computer 140 includes a CPU 141, a bus bridge 142, a memory 143, and a communication controller 144.

  The memories 113, 123, 133, and 143 include a shared memory that is shared between the computers 110, 120, 130, and 140. That is, the memories 113, 123, 133, and 143 hold data including shared data shared by the shared memory.

  As the communication controllers 114, 124, 134, 144, an Ethernet communication controller, a USB communication controller, or the like is used.

  The first communication hub 151 and the second communication hub 152 duplicate the mutual data communication of the communication controllers 114, 124, 134, and 144. As the first communication hub 151 and the second communication hub 152, an Ethernet communication switching hub, a USB hub, or the like is used.

  FIG. 2 shows various data constituting a packet transmitted / received between the computers 110, 120, 130, and 140. This packet includes new data that is retained after the data to be changed in the shared memory is changed, that is, “change data”. Hereinafter, this packet is referred to as a “change data packet”.

  The transmission data size 11 indicates the data length of the changed data packet.

  The packet header 12 indicates a unique header of the modified data packet.

  The transmission computer ID 13 indicates the ID of the computer that transmitted the change data packet. Accordingly, the transmission computer ID 13 is rewritten to the ID of the computer that performs the transfer when the changed data packet received by the computers 110, 120, 130, and 140 is transferred to another computer.

  The transmission right flag 14 indicates the ID of the computer having the right to transmit the modified data packet.

  The encryption code 15 is encryption for designating the base address of the memories 113, 123, 133, and 143 in which the data at that time is changed to the change data, and the transmission order when the transmission order of the change data is randomly changed. Indicates the code. For example, when the encryption code 15 is 32 bits, the combinations of relative addresses that define the transmission order of the change data can be specified as 2 32 (4,294,967,296). Each of the computers 110, 120, 130, and 140 holds a correspondence between the encryption code 15 and the combination of relative addresses that define the transmission order of the changed data as a predetermined encryption table (not shown).

  The base address 16 indicates the base address of the memories 113, 123, 133, and 143 where the changed data is overwritten.

  The change data size 17 indicates the size of the change data.

  The change data 18 indicates the above-described change data, that is, data after change of data to be changed in the shared memory.

The checksum 19 indicates a checksum for detecting an error in data included in the packet.
(Operation of the first embodiment)
Next, the operation when the computer system 100 controls the shared memory using the communication hub will be described with reference to FIG.

  The case where the application program executed by the CPU 111 of the computer 110 whose ID is “1” changes the shared data secured on the memory 113 will be described as an example.

  When the ID specified by the transmission right flag 14 in FIG. 2 is “1”, the CPU 111 transmits the changed data packet to the communication controller 124 of the computer 120 whose ID is “2”. At that time, the changed data packet is transmitted via the bus bridge 112 and the communication controller 114. Immediately after that, the CPU 111 saves the contents of the change data 18 included in the change data packet in the shared memory secured on the memory 113.

  When the ID specified by the transmission right flag 14 is “1” and the transmission of the changed data packet is completed, the CPU 111 transmits the changed data packet whose ID is specified as “2” by the transmission right flag 14. . That is, the right to transmit the modified data packet is transferred from the computer 110 to the computer 120.

  If the ID specified by the transmission right flag 14 is not “1”, the CPU 111 sends the changed data packet to the communication controller 124 of the computer 120 whose computer ID is “2” without changing the transmission right flag 14. Send. At that time, the changed data packet is transmitted via the bus bridge 112 and the communication controller 114. Immediately after that, the CPU 111 saves the contents of the change data 18 included in the change data packet in the shared memory secured on the memory 113.

  The change data packet transmitted from the communication controller 114 is normally received by the communication controller 124 via the first communication hub 151 that is one of the duplex communication hubs. Then, the changed data packet is received by the CPU 121 via the bus bridge 122.

  If the ID specified by the transmission right flag 14 is not “2”, the CPU 121 sends the changed data packet to the communication controller 134 of the computer 130 whose computer ID is “3” without changing the transmission right flag 14. Send. At that time, the changed data packet is transmitted via the bus bridge 122 and the communication controller 124. Immediately after that, the CPU 121 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 123.

  When the ID specified by the transmission right flag 14 is “2”, the CPU 121 transmits the changed data packet to be transmitted to the communication controller 134 of the computer 130 whose computer ID is “3”. At that time, the changed data packet is transmitted via the bus bridge 122 and the communication controller 124. Immediately after that, the CPU 121 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 123.

  When the ID specified by the transmission right flag 14 is “2” and the transmission of the changed data packet is completed, the CPU 121 transmits the changed data packet whose ID is specified as “3” by the transmission right flag 14. . That is, the right to transmit the modified data packet is transferred from the computer 120 to the computer 130.

  The change data packet transmitted from the communication controller 124 is normally received by the communication controller 134 via the first communication hub 151. Then, the change data packet is received by the CPU 131 via the bus bridge 132.

  If the ID specified by the transmission right flag 14 is not “3”, the CPU 131 transmits the changed data packet to the communication controller 144 of the computer 140 having the computer ID “4” without changing the transmission right flag 14. To do. At that time, the changed data packet is transmitted via the bus bridge 132 and the communication controller 134. Immediately thereafter, the CPU 131 saves the content of the change data 18 included in the change data packet in a shared memory secured on the memory 133.

  When the ID specified by the transmission right flag 14 is “3”, the CPU 131 transmits the change data packet to be transmitted to the communication controller 144 of the computer 140 whose computer ID is “4”. At that time, the changed data packet is transmitted via the bus bridge 132 and the communication controller 134. Immediately thereafter, the CPU 131 saves the content of the change data 18 included in the change data packet in a shared memory secured on the memory 133.

  When the ID specified by the transmission right flag 14 is “3” and the transmission of the changed data packet is completed, the CPU 131 transmits the changed data packet whose ID is specified as “4” by the transmission right flag 14. . That is, the right to transmit the modified data packet is transferred from the computer 130 to the computer 140.

  The change data packet transmitted from the communication controller 134 is normally received by the communication controller 144 via the first communication hub 151. Then, the change data packet is received by the CPU 141 via the bus bridge 142.

  If the ID specified by the transmission right flag 14 is not “4”, the CPU 141 does not transmit the changed data packet anywhere. Then, the CPU 141 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 143.

  When the ID specified by the transmission right flag 14 is “4”, the CPU 141 transmits the changed data packet to be transmitted to the communication controller 114 of the computer 110 whose computer ID is “1”. At that time, the changed data packet is transmitted via the bus bridge 142 and the communication controller 144. Immediately thereafter, the CPU 131 saves the content of the change data 18 included in the change data packet in a shared memory secured on the memory 133.

  When the ID specified by the transmission right flag 14 is “4” and the transmission of the changed data packet is completed, the CPU 141 transmits the changed data packet whose ID is specified as “1” by the transmission right flag 14. . That is, the right to transmit the modified data packet is transferred from the computer 140 to the computer 110.

  If communication via the first communication hub 151 fails, the CPU 111, 121, 131, 141 automatically switches the transmission destination to the second communication hub 152, which is the other of the duplex communication hubs. The communication between the computers 110, 120, 130, and 140 is continued.

  Since the data sharing method using communication between shared memories originally transmits a part of the memory in packets, it is difficult to determine the communication contents even if it is intercepted. Therefore, when the base address and data are transmitted, the order in which the data is arranged may be randomly changed using the encryption code 15 included in the changed data packet in FIG. By this encryption, the confidentiality of communication data, that is, change data can be enhanced.

  For example, when the encryption code 15 is 32 bits and 00 00 00 00 (H), the order in which the data is arranged when the base address and data are transmitted is not changed.

  For example, when the encryption code 15 is 32 bits and FF FF FF FF (H), the base address is a value obtained by adding a value of a predetermined encryption table, and the change data is the encryption of the predetermined encryption table. Sorted and sent in the order specified in association with the numerical value of the code.

  In the computer system of FIG. 1, it is not essential that two communication hubs are provided and that the communication lines between the computers 110, 120, 130, and 140 are duplicated. For example, when the communication line between the computers 110, 120, 130, and 140 has sufficient reliability, the communication line need not be duplicated.

  Furthermore, all the various data included in the modified data packet in FIG. 2 are not essential.

  The transmission data size 11 can be omitted, for example, when the data length of the change data packet can be fixed. The packet header 12 can also be omitted if, for example, the device that received the packet can identify that the received packet is a modified data packet by another method.

  Furthermore, the encryption code 15 can also be omitted when there is no possibility of eavesdropping, for example.

  The base address 16 can also be omitted if the address area to be changed can be fixed, for example. For example, the change data size 17 can be omitted if the size of the change data can be fixed. The checksum 19 can also be omitted if, for example, an error during communication can be ignored.

  As described above, the transmission data size 11, the packet header 12, the encryption code 15, the base address 16, and the changed data size 17 checksum 19 can be omitted by setting some conditions.

  As described above, the computer system of the present embodiment has the following effects.

  As described above, the computer system of this embodiment uses only the CPU, memory, and communication controller (Ethernet communication controller, USB communication controller, etc.) that constitute the computer, and the shared memory is stored on the memory of multiple computers by software. To construct. When rewriting the data in the shared memory, the address of the data to be changed and the contents of the data are packetized, and the shared memory is rewritten while relaying between computers.

  Therefore, the computer system of this embodiment does not require dedicated hardware, and can realize the function only with software that operates on a general-purpose computer. Accordingly, it is possible to improve flexibility and reduce costs with respect to design changes.

  Further, the computer system of this embodiment transfers a transmission right flag for rewriting the shared memory between computers. Therefore, it is possible to synchronize the rewriting of the shared memory among a plurality of computers and to prevent the plurality of computers from rewriting data at the same address at the same time.

  In the computer system of the present embodiment, data communication between computers is performed in order to rewrite data in a shared memory built on the memories of a plurality of computers. The line used for communication between computers may be duplicated. In this case, when a communication hub such as an Ethernet hub or a USB hub fails, the communication path is automatically switched. Therefore, reliability can be improved against failures such as disconnection of communication lines and failure of communication hubs.

In the computer system of this embodiment, only a part of the memory is transmitted using a packet. For this reason, it is difficult to determine the communication contents even if a packet is intercepted. Furthermore, in the computer system of this embodiment, an encryption code can be added to the packet. In this case, when the base address and data are transmitted, the order in which the data is arranged can be randomly changed. Therefore, the computer system of this embodiment can improve the confidentiality of communication data.
(Second Embodiment)
The computer system of the present invention can be realized without using a communication hub. The second embodiment shows an example of a shared memory control device that does not use a communication hub.
(Configuration of Second Embodiment)
FIG. 3 is a block diagram showing the configuration of the computer system according to the first embodiment of this invention. The computer system 200 according to this embodiment includes four computers 110, 120, 130, and 140. The IDs of the computers 110, 120, 130, and 140 are “1”, “2”, “3”, and “4”, respectively. As described above, the computer system 200 according to the present embodiment is obtained by removing the first communication hub 151 and the second communication hub 152 from the computer system 100 according to the first embodiment. Since the configurations of the computers 110, 120, 130, and 140 and their internal configurations are the same as those of the computer system 100, description thereof is omitted.

However, unlike the computer system 100, the communication controllers 114, 124, 134, and 144 directly communicate with each other without using a communication hub in the computer system 200. Packets transmitted and received between the computers 110, 120, 130, and 140 are the changed data packets in FIG.
(Operation of Second Embodiment)
Next, in the computer system 200, an operation when the shared memory is controlled without using a communication hub will be described with reference to FIG.

  The case where the application program executed by the CPU 111 of the computer 110 whose ID is “1” changes the shared data secured on the memory 113 will be described as an example.

  When the ID specified by the transmission right flag 14 in FIG. 2 is “1”, the CPU 111 transmits the changed data packet to the communication controller 124 of the computer 120 whose ID is “2”. At that time, the changed data packet is transmitted via the bus bridge 112 and the communication controller 114.

  If the ID specified by the transmission right flag 14 is not “1”, the CPU 111 transmits the message to the communication controller 124 of the computer 120 whose computer ID is “2”. At that time, the changed data packet is transmitted via the bus bridge 112 and the communication controller 114. Immediately after that, the CPU 111 saves the contents of the change data 18 included in the change data packet in the shared memory secured on the memory 113.

  When the transmission of the modified data packet addressed to the communication controller 124 fails, the CPU 111 transmits the modified data packet addressed to the communication controller 134 of the computer 130 whose ID is “3”. If the transmission of the modified data packet addressed to the communication controller 134 also fails, the CPU 111 transmits the modified data packet to the communication controller 144 of the computer 140 whose ID is “4”.

  When the ID designated by the transmission right flag 14 is “1” and the transmission of the changed data packet is completed, the CPU 111 sends the ID of the computer (2, 3, or The change data packet specified in 4) is transmitted.

  Immediately after the transmission of the change data packet to the communication controller 124, the communication controller 134, or the communication controller 144, the CPU 111 stores the contents of the change data 18 included in the change data packet in the shared memory secured on the memory 113. save.

  The change data packet transmitted from the communication controller 114 is normally received by the communication controller 124. Then, the changed data packet is received by the CPU 121 via the bus bridge 122.

  If the ID specified by the transmission right flag 14 is not “2”, the CPU 121 confirms the transmission computer ID of the changed data packet. Then, when the transmission computer ID is “1”, that is, when the transmission source of the modified data packet is the communication controller 114, the CPU 121 communicates the modified data packet to the communication controller 124 with the communication of the computer 130 with the computer ID “3”. The data is transmitted to the controller 134.

  When the ID specified by the transmission right flag 14 is “2”, the CPU 121 transmits the changed data packet to be transmitted to the communication controller 134 of the computer 130 whose computer ID is “3”. At that time, the changed data packet is transmitted via the bus bridge 122 and the communication controller 124. Immediately after that, the CPU 121 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 123.

  If the transmission of the changed data packet addressed to the communication controller 134 fails, the CPU 121 transmits the changed data packet addressed to the communication controller 144.

  If the transmission of the changed data packet addressed to the communication controller 144 fails, the CPU 121 transmits the changed data packet addressed to the communication controller 114.

  Immediately after the transmission of the change data packet to the communication controller 134, the communication controller 144, or the communication controller 114, the CPU 121 stores the contents of the change data 18 included in the change data packet in the shared memory secured on the memory 123. save.

  When the ID specified by the transmission right flag 14 is “2” and the transmission of the changed data packet is finished, the CPU 121 sends the ID of the computer that can transmit the ID of the transmission right flag 14 (3, 4, or The change data packet specified in 1) is transmitted.

  The change data packet transmitted from the communication controller 124 is normally received by the communication controller 134. Then, the change data packet is received by the CPU 131 via the bus bridge 132.

  If the ID specified by the transmission right flag 14 is not “3”, the CPU 131 confirms the transmission computer ID of the changed data packet. Then, when the transmission computer ID is “1”, that is, when the transmission source of the modified data packet is the communication controller 114, the CPU 131 transmits the modified data packet to the communication controller 144 of the computer 140 whose computer ID is “4”. . At that time, the changed data packet is transmitted via the bus bridge 132 and the communication controller 134. Immediately thereafter, the CPU 131 saves the content of the change data 18 included in the change data packet in a shared memory secured on the memory 133.

  When the ID specified by the transmission right flag 14 is “3”, the CPU 131 transmits the change data packet to be transmitted to the communication controller 144 of the computer 140 whose computer ID is “4”. At that time, the changed data packet is transmitted via the bus bridge 132 and the communication controller 134. Immediately thereafter, the CPU 131 saves the content of the change data 18 included in the change data packet in a shared memory secured on the memory 133.

  If the CPU 131 fails to transmit the changed data packet to the communication controller 144, the CPU 131 transmits the changed data packet to the communication controller 114.

  If the transmission of the modified data packet addressed to the communication controller 114 fails, the CPU 131 transmits the modified data packet addressed to the communication controller 124.

  When the ID designated by the transmission right flag 14 is “3” and the transmission of the changed data packet is finished, the CPU 131 transmits the ID of the computer that can transmit the ID of the transmission right flag 14 (4, 1, or The changed data packet specified in 2) is transmitted.

  The change data packet transmitted from the communication controller 134 is normally received by the communication controller 144. The changed data packet is received by the CPU 141.

  If the ID specified by the transmission right flag 14 is not “4”, the CPU 141 confirms the transmission computer ID of the changed data packet. Then, when the transmission computer ID is “1”, that is, when the transmission source of the modified data packet is the communication controller 114, the CPU 141 does not transmit the modified data packet anywhere. Then, the CPU 141 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 143.

  When the ID specified by the transmission right flag 14 is “4”, the CPU 141 transmits the changed data packet to be transmitted to the communication controller 114 of the computer 110 whose computer ID is “1”. At that time, the changed data packet is transmitted via the bus bridge 142 and the communication controller 144. Immediately after that, the CPU 141 stores the contents of the change data 18 included in the change data packet in a shared memory secured on the memory 143.

  When the transmission of the changed data packet addressed to the communication controller 114 fails, the CPU 141 transmits the changed data packet addressed to the communication controller 124.

  If the transmission of the modified data packet addressed to the communication controller 124 also fails, the CPU 141 transmits the modified data packet addressed to the communication controller 134.

  When the ID specified by the transmission right flag 14 is “4” and the transmission of the changed data packet is finished, the CPU 141 transmits the ID of the computer (1, 2, or 2) that can transmit the ID of the transmission right flag 14 The changed data packet specified in 3) is transmitted.

  In the computer system of FIG. 3, it is not essential that the communication lines between the computers 110, 120, 130, and 140 are duplicated. For example, when the communication line between the computers 110, 120, 130, and 140 has sufficient reliability, the communication line need not be duplicated.

  As described above, the computer system according to the second embodiment also controls the shared memory using data communication between computers. At that time, dedicated hardware is not required, and the function can be realized only by software operating on a general-purpose computer. Accordingly, it is possible to improve flexibility and reduce costs with respect to design changes.

  Further, since the transmission right flag can be transferred, it is possible to synchronize the rewriting of the shared memory and to prevent a plurality of computers from rewriting data at the same address at the same time.

  Furthermore, since it can respond | correspond to the duplication and encryption of a communication path as needed, reliability and concealment can be improved.

      100, 200, 300 Computer system

Claims (6)

A first arithmetic unit, a first bus bridge connected to the first arithmetic unit, and a first bus bridge connected to the first bus bridge or the first arithmetic unit and holding data including shared data A first computer including a first storage unit and a first communication control unit connected to the first bus bridge;
A second arithmetic unit, a second bus bridge connected to the second arithmetic unit, and data including the shared data connected to the second bus bridge or the second arithmetic unit are held. A second storage unit, and a second computer including a second communication control unit connected to the second bus bridge and the first communication control unit,
The first computer has a change data packet for changing the shared data and a change data packet including identification information designating a computer having a transmission right, and the identification information is designated to have the transmission right. A computer system that transmits to the second computer when the computer is on. The computer system according to claim 1, wherein the change data packet includes encryption information for encrypting the change data. The computer system according to claim 1 or 2, wherein the first communication control unit and the second communication control unit are connected by a plurality of communication lines. 4. The computer system according to claim 3, wherein each of the plurality of communication lines connects the first communication control unit and the second communication control unit via a hub. A first computing unit;
A first bus bridge connected to the first arithmetic unit;
A first storage unit connected to the first bus bridge or the first arithmetic unit and holding data including shared data;
A first computer including a first communication control unit connected to the first bus bridge;
When a change data packet including change data for changing the shared data and identification information designating a computer having a transmission right is designated as having the transmission right by the identification information, a second A second bus bridge connected to the second computing unit; a second bus bridge connected to the second computing unit; and a second bus bridge connected to the second bus bridge or the second computing unit for holding data including the shared data. A computer, comprising: a storage unit; and a second computer including a second communication control unit connected to the second bus bridge and the first communication control unit. To change the shared data from a first computer including a first storage unit holding data including shared data to a second computer including a second storage unit storing data including the shared data A shared memory control method, comprising: transmitting a change data packet including change data and identification information designating a computer having a transmission right when the first computer has the transmission right.

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