A control system for multi-processor system

Abstract: An input/output request control system in a multi-processor system includes a plurality of information processing modules (PM). The system comprises a plurality of input/output adapters (ADP) commonly used by each of said information processing modules and a plurality of input/output devices (DVC) divided to be controlled by respective input/output adapters. An input/output request maintaining table (LDVC) manages input/output requests from respective information processing modules for each of the input/output devices controlled by said information processing modules by using a queue. Input/output requests from respective information processing modules are processed based on the state of the input/output request maintaining table and the input/output devices.

Description: The present invention relates to a multi-processor system formed of a plurality of information processing modules, and more particularly to a control system for effectively processing an input and output request from respective information processing modules and for effectively processing interruption requests from respective input and output devices. In the following explanation, respective elements of a device are designated by the following abbreviations. PM: information processor module DVC: input/output device ADP: input/output adapter IOC: input/output controller IOBUS: input/output bus for connecting PM and ADP DVBUS: device bus for connecting ADP and DVC CPU: information processing unit in PM MSU: memory storage unit in PM PIBC: PM-IOBUS connector PMBUS: PM bus connecting CPU, MSU and PIBC in PM AIBC: ADP-IOBUS connector ADBC: ADP-DVBUS connector APU: ADP processing unit CSU: control storage unit in ADP LDVC: logical input/output request holding table for a PM-DVC correspondence provided in CSU PDVC: physical input/output request holding table corresponding to DVC PMIC: PM interruption control table Generally speaking, where a plurality of PMs are provided, it is necessary for a system to hold data such as a data base or a user file as one source. Thus, it is usually stored in a DVC (input/output device) such as a magnetic disc and is commonly used by a plurality of PMs. When a PM accesses a DVC, the DVC is already executing an input/output request from another PM, it must wait until this request is completed. Thus, it is necessary to reissue the input/output request when the DVC becomes available. This process is performed by a software of PM. However, this results in an overhead caused by an interruption or input/output request. When many PMs are provided, and even when a PM reissues the input/output request, a different PM may already be using the DVC. Therefore, the number of reissuances of the input/output requests increases, but the overall system capability does not increase in spite of the increased number of PMs. Figure 1 shows an example of a conventional multi-processor system comprising a PM (information processing module) 1, an ADP (input/output adapter) 2, DVC (input/output device) 3 and an IOC (input/output controller) 6. 8 to 16 PMs, for example, are provided. PM 1 and ADP 2 are provided on a one-by-one basis and all the DVCs are controlled by a single common IOC 6. Respective PMs 1 and ADPs 2 operating under the supervision of PMs 1 access DVC 3 through a single common IOC 6. The conventional system shown in Figure 13 has recently been used in general purpose computers. Respective ADPs 2 are separately provided such that they are exclusively owned by the upper PM 1. IOC 6 for controlling an input/output of respective DVCs 3 is provided with a port to be connected to a plurality of ADPs 2. In this case, ADP 2 is provided exclusively for a predetermined PM 1 and always receives an input/output request from the PM 1. ADP 2 notifies IOC 6 of the input/output request. Where the requested DVC 3 is operating in accordance with an input/output request by another PM (through ADP), IOC 6 notifies the ADP 2 performing the input/output request that the DVC 3 is being used and the DVC does not receive the input/output request from the PM 1. ADP 2 reports this status (designating that DVC 3 is being used) to PM 1 through an interruption operation and completes the input/output process. The software of the PM 1 reissues an input/output request after waiting a predetermined time after receiving the report. When DVC 3 returns a response stating that a DVC has become available, some IOCs 6 have a function of reporting this availability through an interruption. In this case, the software of PM 1 reissues an input/output request after receiving the interruption. ADP 2 is also provided with a function of waiting for the DVC 3 to become available and ADP 2 reissues the input/output request, thereby decreasing the PM's software and overhead. Conventionally, the DVC 3's availability upon a reissuance of input/output request is not certain. With an increase in the number of PMs 1 and the rate of DVC's being used, the reissuing frequency increases. As the reissuance process is not necessary in the original system, the increase of the reissuance process cause a system capability to be lowered. Further, where PMs 1/ADPs 2 of different models use a common DVC 3, the number of times the DVC is required to perform the reissuance process varies between different models. Even when these different PMs simultaneously start the reissuance process, the reissuance of the input/output request by a slower PM1 has a high possibility of failure, thereby greatly deteriorating the capability of the process of the PM. Figure 2 shows another conventional system in which a communication path 7 is provided between PMs, and respective PMs 1 have a single ADP 2 and a plurality of DVCs 3. In this system, DVCs 3 as well as ADP 2 are exclusively owned and accessed by a particular PM 1. Where a particular PM 1 needs to access a DVC 3 which is not under its supervision, the particular PM 1 asks another PM 1 to which the DVC 3 is connected to perform an input/output operation through a communication path 7 between PMs 1, and sends and receives the transfer data through this communication path 7. In this system, only one PM 1 is capable of issuing an input/output request to a certain DVC 3 and the software of the PM 1 can always control an operating state of the DVC 3. Therefore, the system shown in Figure 2 can prevent the occurrence of a state in which the DVC is being used and a reissuance of the input/output request, which are caused in the conventional system shown in Figure 1. However, in this system, the PM 1 which is asked to issue the input/output request consumes a memory resource and an overhead of a communication between PMs. Thus, this system is disadvantageous compared with a structure in which a direct access path is provided from the PM 1 to the DVC 3. In particular, the overhead of the communication between PMs greatly depends on the frequency of access to a DVC 3 which is under the control of another PM 1. Thus, it is necessary to decrease the volume of communication between PMs by using a special method of storing data in respective DVCs or by limiting an application to be processed to a special purpose and use, thereby preventing a decrease in system capability. This method is very disadvantageous in that it is difficult to build a system with high performance and the purpose and use of the system is limited, making it unsuitable as a general purpose system. If a DVC makes an interrupt request to a PM, when the PM is already executing an interrupt request from another DVC, it must wait until this request is completed. Thus, it is necessary to reissue the interrupt request when the PM becomes available. Where a PM cannot accept a request of an interruption because the interupt is masked by the software, it is also necessary to reissue the interrupt request. This process can be performed by firmware in an adaptor. As I/O requests to a plurality of DVCs transmitted from a plurality of PMs are simultaneously procesed in the adapter, it is necessary to deal in parallel with the completion interrupts which are made upon the completion of the I/O requests. However, this cannot be effectively achieved by the conventional art. An example of the conventional art is to found in EP 0 029 394 which discloses a procedure and a device for keeping count of and managing asynchronous events emanating from peripheral devices. A further example is to be found in EP 0 059 838 which discloses a data-processing system having a plurality of host processors and peripheral devices. It uses a hierarchical group control method and apparatus. An object of the present invention is to maintain direct access from respective PMs to a DVC and decrease overheads caused by reissuance of an input/output request in PM 1, thereby preventing the processing performance of a multi-processor system from being decreased. Another object of the present invention is to reduce the occurrence of a state of waiting for an interrupt to other PMs depending on whether the interrupt to a particular PM is accepted, when the interrupt request from respective DVCs to the PM is processed, thereby preventing the processing performance of a multi-processor system from being decreased. According to a first aspect of the present invention there is provided a multi-processor system comprising an input/output request control arrangement, said arrangement comprising: a plurality of input/output adapters (ADP); a plurality of input/output devices (DVC); and a plurality of information processing modules (PM); and characterised in that the plurality of information processing modules (PM) are for using the input/output adapters (ADP) and in that the input/output devices (DVC) are divided to be controlled by respective input/output adapters; and further comprising: means for providing a logical input/output request holding table (LDVC) for managing input/output requests from respective information processing modules for each of said input/output devices (DVC) controlled by said information processing modules by using a drive queue; and means for processing input/output requests from respective information processing modules based on a state of said input/output request maintaining table and the input/output devices. According to a second aspect of the present invention there is provided a multi-processor system comprising an interrupt request control arrangement, said arrangement comprising: a plurality of input/output adapters (ADP); a plurality of input/output devices (DVC); and a plurality of information processing modules (PM) and characterised in that the information processing modules (PM) are for using the input/output adapters (ADP) and in that the input/output devices (DVC) are divided to be controlled by respective input/output adapters; and further comprising: means for providing an interrupt request maintaining table for managing interrupt requests from respective input/output devices to each of said information processing modules by using a queue; and means for processing interrupt requests of respective input/output devices based on the state of said interrupt request maintaining table and the input/output devices. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the attached drawings, in which: Figure 1 shows a structural view of a conventional computer system, Figure 2 shows a structural view of another conventional computer system, Figure 3 shows a block diagram for explaining a principle of the present invention, Figure 4 shows a structural view of a first embodiment of the present invention, Figure 5 shows an explanatory view of a control information format in the first embodiment of the present invention, Figure 6 shows a structural view of a control table of the first embodiment, Figure 7 shows an explanatory view of a wait queue of an LDVC, Figure 8 shows an explanatory view of a format of the LDVC, Figure 9 shows an explanatory view of a format of the PDVC, Figure 10 shows an explanatory view of a drive wait queue of the PDVC, Figure 11 shows a flowchart of a main process of an ADP control program in the present invention, Figure 12 shows a flowchart of a process of an I/O command receipt, Figure 13 shows a flowchart of an I/O command execution, Figure 14 shows a flowchart of a reconnection process of the first embodiment, Figure 15 shows a structural view of a second embodiment of the present invention, Figure 16 shows a structural view of a control table of the second embodiment; Figure 17 shows an explanatory view of a queue of the LDVC; Figure 18 shows an explanatory view of a format of the PMIC; Figure 19 shows an explanatory view of an interrupt wait queue of the PMIC; Figure 20 shows a flowchart of an interrupt process 1 in the second embodiment; and Figure 21 shows a flowchart of an interrupt process 2 in the second embodiment; Figure 3 shows the first principle of the present invention. Respective PMs 1 (information processing modules) commonly use a plurality of ADPs (input/output adapters) 2. Respective ADPs 2 have their own DVCs which are under their control. Access to a discretional DVC 3 from PMs 1 is made through an ADP 2 to which the discretional DVC 3 belongs. Means for managing input/output requests made to the discretional DVC 3 by respective PMs 1 using a queue of PMs 1 per DVC 3 is provided for respective ADPs 2. A plurality of PMs (Information processing module) 1 constitute a multi-processor system. Adapter 2 processes an input/output request from respective PMs 1. DVC 3 comprises a magnetic disc device or a magnetic tape device, for example. IOBUS 4 connects a discretional PM 1 to a discretional ADP 2 and transmits data and control information. DVBUS (device bus) 5 connects respective ADPs 2 to a plurality of DVCs 3 which are under their control and transmits data control information. CSU (control storage unit) 22 is provided in ADP 2. CSU 22 comprises an input/output request holding table LDVC 221 for holding an input/output request from PMs (#0, #1...) 1 to respective DVCs 3 (#0, #1...) which are controlled by respective ADPs 2. Input/output request holding table LDVC 221 has a queue management function. Queue 222 relating to the LDVC 221 for managing process sequence of input/output requests from respective PMs with regard to respective DVCs is provided. Control program 223 manages input/output requests from respective PMs by using LDVC 221 and APU processes the input/output requests in the order in which they are connected to queue 222 when the DVC 3 is available. As shown in Figure 3, when a PM 1 produces an input/output request to a DVC 3, the PM 1 issues an input/output request to an ADP 2 to which the DVC 3 is connected as shown in the control program. APU of ADP 2 once stores the input/output request from the PM 1 in the LDVC corresponding to the PM/DVC. The ADP 2 connects the input/output request to the drive queue which is provided for each of the DVCs 3 and performs a process for the DVC 3 in the order of arrival of the input/output requests. When input/output requests are made to a plurality of DVCs 3, DVCs 3 also form a queue to perform processes in a sequential manner. Thus, the above structure prevents respective PMs 1 from judging that the DVCs 3 are being used. ADP 2 needs not reissue a useless input/output request to DVCs 3 and can avoid overhead caused by the reissuance of the input/output request. Further, as a failure does not occur upon the reissuance of the input/output request, an extreme decrease in performance resulting from varying performance levels of PMs 1 does not occur. The input/output operation of the DVC 3 is directly conducted by respective PMs 1 with regard to an issuance of input/output request as well as data transfer in the same manner as the conventional system shown in Figure 1. Therefore, the problem of a communication overhead among PMs 1 is removed and optimization of the arrangement of data is achieved, thereby providing a high-performance multi-processor system. According to the second principle of the present invention, respective PMs 1 commonly use a plurality of ADPs. Respective ADPs 2 have their own DVCs. Access to a discretional DVC 3 from a PM 1 is made through an ADP 2 to which the discretional DVC 3 belongs. Means for managing interrupt requests made to the PM 1 by discretional DVCs 3 using a queue of DVCs 3 per PM is provided for respective ADPs 2. CSU 22 comprises an input/output request holding table LDVC 221 for holding an interrupt request from DVCs (#0, #1...) 1 to respective PMs 3 (#0, #1...) which are controlled by respective ADPs 2. The input/output request holding table LDVC 221 for holding an interrupt request is the same as the input/output request holding table for the input/output request. Input/output request holding table LDVC 221 has a queue management function. Queue 224 relating to the LDVC 221 for managing process sequence of interrupt requests from respective DVCs with regard to respective PMs is provided. Control program 223 manages interrupt requests from respective DVCs by using LDVC 221 and APU processes the interrupt requests in the order in which they are connected to queue 224 when the PM1 is available. The queue comprises drive queue 222 for linking cells in a row direction of the LDVC 221 and interrupt queue 224 for linking cells in a column direction of the LDVC. As shown in Figure 3, when a DVC 3 produces an interrupt request to a PM 1, the DVC 3 issues an interrupt request (REQ) to an ADP 2 to which the PM 1 is connected as shown in the control program. APU of ADP 2 once stores the interrupt request from the DVC 3 in the LDVC corresponding to the DVC/PM. The ADP 2 connects the interrupt request to the interrupt queue which is provided for each of the PMs 1 and performs a process for the PM 1 in the order of arrival of the interrupt requests. When interrupt requests are made to a plurality of PMs 1, PMs 1 also form a queue to perform processes in a sequential manner. Thus, the above structure decreases an occurrence of a state of waiting for an interrupt to other PMs depending on whether the interrupt to a particular PM is accepted, when the interrupt request from respective DVCs to the PM is processed, thereby preventing the processing performance of a multiprocessor system from being decreased. As I/O requests to a plurality of DVCs transmitted from a plurality of PMs are simultaneously processed by the ADP 2, the ADP 2 can deal in parallel with the completion interrupts which are made upon completion of the I/O requests. As shown in Figure 4, a multi-processor system of a first embodiment of the present invention comprises PM 1, ADP 2, DVC 3, IOBUS 4, DVBUS 5, CPU 11, MSU 12, PIBC (PM-IOBUS connector)13, PMBUS (PM bus) 14, APU 21, CSU 22, AIBC(ADP-IOBUS connector) 23, ADBC (ADP-DVBUS connector) 24, ADBUS (ADP bus) 25, and LDVC (input/output request holding table) 221. CPU 11 in a discretional PM 1 executes a program stored in MSU 12 and performs a series of processes. When an instruction for requesting an input/output operation is executed in PM 1, CPU 11 designates necessary information such as ADP and DVC which should be a subject of an input/output request and instructs PIBC 13 to ask ADP 2 for the input/output operation. PIBC 13 transmits the input/output request to AIBC 23 in ADP 2 through IOBUS 4. AIBC 23 notifies APU 21 that the input/output request is received and APU 21 stores the input/output request in LDVC 221 corresponding to the PM issuing the input/output request and the subject DVC and provided in CSU 22, and registers LDVC 221 in a queue for awaiting the input/output operation. When DVBUS 5 is not used and an input/output request is made for the DVC which is not operated, APU 21 issues the input/output request for the DVC in accordance with the sequence of the queue and sequentially executes the input/output request held in LDVC 221. Figures 5A to 5D show a format of a control information used in the embodiment of the present invention. Figure 5A represents an input/output instruction executed by a CPU in a PM, Figure 5B shows a parameter of an input/output instruction, Figure 5C shows a command for controlling an input/output, and Figure 5D shows a status block for controlling an input/output. The input/output command in Figure 5A comprises an operation code (OP), the machine number of the ADP to be used (ADP #), the machine number of the DVC which is the subject of the access (DVC #) and the address of the parameter (Parameter Adrs) shown in Figure 5B. Parameters shown in Figure 5B comprise an address (Command Adrs) for storing the command shown in Figure 5B and an address (Status Blk Adrs) for the status block shown in Figure 5D for storing completion information. The command as shown in Figure 5C includes an operation code (OP) such as read, write, seek, flag (flg), data count (Data Count) and data storing address in a main storage (LSU Adrs) and forms a channel program by combining a plurality of commands in a chain. A status block as shown in Figure 5D includes a status (Status) designating a completion status, a data count for the remaining data upon an abnormal completion and an address of a final command. Figure 6 shows a control table for maintaining an input/output request in the first embodiment of the present invention. The control table is provided corresponding to the DVC (#) and comprises LDVC and PDVC. An LDVC comprises a table for managing input/output requests from respective PMs for a single DVC by entering them into a queue in the arriving sequence. PDVC comprises a table for managing the input/output request sequence when the input/output requests from a plurality of PMs arrive at a plurality of DVCs provided under the control of an ADP. Figure 7 shows an example of a queue of the LDVC. In this case, input/output request from PMs for a DVC#0 arrive at an ADP in the sequence PM#2, PM#0 and PM#1. Therefore, as shown in Figure 7, a queue in which PM#2, PM#0 and PM#1 are linked in sequence beginning with PM#2 is formed for LDVC#0. LDVC#0 is subjected to PDVC#0 and LDVC#0 is activated when PDVC#0 reaches a head of a queue of PDVC and comes in an executing state. At this time, input/output request PM#2, which is provided at the head of the queue of LDVC#0, comes in an executing state and input/output requests PM#0 and PM#1 come in an execution-awaiting. When an execution of the input/output request from PM#2 is completed, a request of PM#2 is removed from the LDVC queue and instead PM#0 comes to the head of the LDVC queue. However, at this time, PDVC#0 is removed from the head of the PDVC queue and is made to wait for an execution. Therefore, the input/output request of PM#0 is kept waiting for an execution until PDVC#0 comes in the next executing state. Figure 8 shows a format of LDVC. The following state information is provided for a status (Status) in the LDVC. IDLE: nothing is done WAIT: availability of the PDVC is awaited WORK: an input/output request comes at the head of the queue and executes the input/output operation IRQW: LDVC is connected to an interruption queue as shown in Figure 19 and waits for the issuance of the IRQ bus command. When LDVC reaches the head of the interruption queue i.e. LDVC reaches a head of the LDVC interruption queue and the head of PMIC interruption queue, IRQ command is issued and the IRQW state is changed to IRQEX state. As described above, PMIC corresponds to PM. IRQEX: LDVC reaches the head of an interruption queue and PMIC reaches the head of PMIC interruption queue. Thus, IRQ bus command is issued and a notification from PM as to whether IRQ bus command is accepted is awaited. If the notification of the acceptance of the interruption is yes, the state is changed to the state of IACKW and LDVC is removed from the interruption queue. If the notification of the acceptance of the interruption is no, PMIC is changed to be connected to the last of PMIC interruption queue and the state of IRQEX is returned to the state of IRQW. IACKW: This shows that the interruption request is accepted by PM and ADP2 waits for IACK bus command. In this time, LDVC is not connected to the interruption queue and drive queue. ADP2 receives IACK bus command and is returned to IDLE state and waits for a new I/O command. In addition, LDVC further comprises addresses (Command ADRS, Status Blk Adrs) of the command and the status block of the table, as shown in Figure 5C and link information (Next LDVC, Prev.LDVC) for linking with the next and previous LDVC for forming a queue. Figure 9 designates a format of the PDVC. IDLE: nothing is done (i.e., there is no LDVC in an executing state or a waiting state) WAIT: the availability of DVBUS is awaited WORK: an input/output operation is being executed DISC: while the DVC is operating, DVBUS is open (i.e. disconnected) The PDVC has the machine number of PM of the input/output request source (Active PM#) and the link information (Next PDVC and Prev.PDVC) for connecting the PDVC to the next or previous PDVC to form a queue. Figure 10 shows an example of the queue of the PDVC. Input/output requests from PM#0, PM#1 and PM#2 are issued to DVC#0, DVC#1 and DVC#2 and are maintained in the LDVC. PDVC#2, PDVC#0 and PDVC#1 are connected to a queue in this order in accordance with an arriving sequence of input/output requests. The LDVC of PM #0 forms a queue for PDVC #1. LDVCs of PM#1, PM#2 and PM#0 form a queue for PDVC#0 and LDVC of PM#0 forms a queue for PDVC#1. A process flow of a control program of an ADP for processing an input/output request by using the PDVC and LDVC is explained by referring to Figures 11 to 14. Figure 11 is a flowchart of a main process of the ADP control program. When the power source is thrown in, an initialization process is performed and when an I/O (input/output) instruction comes from a PM, a process of receiving the I/O instruction is performed. When a PDVC is in a waiting state, the process waits until DVBUS between ADP-DVC becomes available, thereby executing the I/O command. The completion of this execution of the I/O command is performed by an interrupt process (described later) from ADP to PM. When the DVC transmits a reconnection request, their connection process is performed for the PDVC in the DISC state. Figure 12 shows a flowchart of a process in which APU 21 of ADP2 receives an I/O command. When a request transmitted from a PMn to a DVCm arrives at ADP2 and when OPCODE is not IACK (interrupt acknowledge), the request is judged as the I/O command, and the ADP2 examines the state of the LDVCnm and sends an I/O command "receipt rejection" to PMn as a reply, in a state other than IDLE. When LDVCnm is IDLE, the process sends an I/O command "receipt completion" to PMn to change the state of LDVCnm to WAIT and add LDVCnm to the LDVC queue after storing parameter information in LDVCnm. Next, the ADP examines the state of LDVCm and the process returns to the main process in states other than IDLE. In case of IDLE, the ADP changes the state of PDVC to WAIT and adds PDVCm to the PDVC queue, thereby returning to the main process shown in Figure 11. When OPCODE is IACK, the interrupt request is accepted by PM, a state of LDVCnm is made empty, i.e., IDLE, thereby returning to the main process. Figure 13 shows a flowchart of an I/O command execution. n designates the machine number of PM and m designates the machine number of DVC. When the DVBUS is usable, the process changes the state of the PDVCm for DVCm and the state of LDVCnm from PMn to DVCm to Work. Next, the process executes an input/output operation. The input/output operation is executed by first sending a command to DVC, transferring Data to DVC and examining whether DVBUS is disconnected. As a disconnection of DVBUS, there are a case where all the input/output operations are completed and a case where DVC is temporarily disconnected during a mechanical operation of the DVC. When all the input/output processes are not completed, the state of PDVCm is changed to Disc and is removed from the queue and returned to the main process. When all the input/output operations are completed, LDVCm is removed from LDVC queue and the interrupt process 1 ( shown in Figure 20) is executed. When the length of the LDVC drive queue is not 0, the state of PDVCm is changed to Wait and PDVCm is moved to the last of the PDVC drive queue and returned to the main process shown in Figure 11. When the length of the LDVC drive queue is 0, the state of PDVCm is changed to Idle and PDVCm is removed from the PDVC drive queue and returned to the main process. Figure 14 shows a flowchart of a reconnection process. When the DVCm in the disconnecting state, makes a reconnection request, the process examines whether the state of the corresponding PDVCm is Disc. If it is other than Disc, the rejection of the reconnection is notified to DVC and the process is completed by releasing the DVBUS and returns to the main process shown in Figure 11. If the state of PDVCm is Disc, it is changed to Work, the PDVCm is moved to the head of the PDVC queue, the process receives the reconnection and reopens the input/output operation, and is returned to 1 ○ in the I/O command execution shown in Figure 11. According to the present invention, the access bus from respective PMs to the discretional DVC can be directly set through an ADP without going through other PM routes and the PM having issued the input/output request need not reissue the input/output request even if the DVC to be accessed is being used, and need not communicate with other PMs. This decreases the overhead and improves the performance of a multi-process system. As shown in Figure 15, a multi-processor system of a second embodiment of the present invention comprises PM 1, ADP 2, DVC 3, IOBUS 4, DVBUS 5, CPU 11, MSU 12, PIBC (PM-IOBUS connector)13, PMBUS (PM bus) 14, APU 21, CSU 22, AIBC(ADP-IOBUS connector) 23, ADBC (ADP-DVBUS connector) 24, ADBUS (ADP bus) 25, and LDVC (input/output request holding table) 221. APU 21 in a discretional ADP 2 executes a program stored in CSU 22 and performs a series of processes. When an instruction for requesting an interrupt operation is executed in ADP 2, APU 21 designates necessary information such as PM which should be a subject of an interrupt request and instructs AIBC 23 to ask PIBC 13 of PM 1 for the interrupt operation. AIBC 23 transmits the interrupt request to PIBC 13 in PM 1 through IOBUS 4. PIBC 13 notifies CPU 11 that the interrupt request is received and APU 21 stores the interrupt request in LDVC 221 corresponding to the DVC issuing the interrupt request and the subject DVC and provided in CSU 22, and registers LDVC 221 in a queue for awaiting the interrupt operation. When DVBUS 5 is not used and an interrupt request is made to the PM which is not operated, APU 21 issues the interrupt request to the PM in accordance with the sequence of the queue and sequentially transmits the interrupt request held in LDVC 221 to CPU 11. Above interruption operation will be described more in detail. The following three kinds of definitions of a state of storing circuit INTSPS state RED 131 provided in PIBC 13. IDLE: This designates a state in which an interruption receipt is possible. PMIRQ(PM Interrupt Request) is off. When IRQ (Interrupt Request) bus command is received from ADP2, this state is changed to an IRQ state. IRQ: This designates a state in which an interruption request is reserved. PMIRQ is on. A new interruption from ADP 2 is not accepted. CPU 11 accepts an interruption and when PCMIACK (PM Interrupt Acknowledge) turns on, the state is changed to IACKW (Interrupt Acknowledge Wait). IACKW: This designates a state in which IACK bus command transmission is reserved. PMIRQ is off. A new interruption from ADP2 is not accepted. When PIBC accesses an I/O bus and an IACK bus command is transmitted, the state of INTSTS REG 131 is changed to IDLE. PM comes to a state in which the interrupt is acceptable. A mechanism of an interruption occurrence for a single PM is as follows. When a DVCm transmits an interruption request to a PM, APU 21 (comprising a firmware operating on the APU) previously stores the detailed interruption information in the area of MSU 12 designated by PM upon an issuance of an I/O command as a status block. APU 21 sets interruption information (such as ADP#, DVC#, PM# and interruption cause code) in an interruption production circuit (INTREQ REG) 231 in AIBC 23 and instructs AIBC 23 to allow the interruption to PM to start. AIBC 23 accesses the I/O bus and transmits a bus command (an IRQ bus command) of an interruption request to the designated PM. The above designated interruption information is included in this bus command. When PIBC 13 receives an interruption command from AIBC 23, and INTSTS REG 131 is empty (i.e., in an Idle state), the interruption information is set in INTSTS REG 131 and interruption request (PMIRQ) to CPU 11 turns on and notifies ADP 2 of the interruption receipt. When INTSTS REG 131 is not empty, ADP 2 is notified that the interruption is not accepted. These notifications are transmitted to ADP 2 through a response signal line of IOBUS. This response signal line is transmitted to a unit on a transmitting side by a unit on a receiving side upon receiving the bus command. The content of the response signal of AIBC 23 is notified to APU 21 through an interruption to APU 21. APU 21 can thus determine whether the interruption transmission is successful. When the interruption transmission fails, the interruption request is tried again later. When PMIRQ is on, and the interruption receipt is possible, PMIACK turns on, thereby executing the interruption operation. Whether the interruption receipt is possible depends on a state of an interruption mask in CPU 11. This is a well known technology. A software may sometimes run for a long time in an interruption prohibition state. In this case, INTSTS REG 131 is maintained in this state (i.e., in the state of IRQ). When PMIACK turns on, PIBC 13 turns off the PMIRQ and accesses the IOBUS by putting INTSTS REG 131 into an IACKW state in which IACK transmission is waited and transmits a bus command (IACK bus command) for the interruption receipt to ADP 2. When the transmission of the bus command is completed, INTSTS REG 131 is returned to an IDLE state and thus a receipt of a new interruption becomes possible. When AIBC 23 receives IACK, as shown in Figure 12, it notifies APU 21 by an interruption operation, for example. APU 21 returns LDVC 221 to a state of IDLE when it receives IACK. Figure 16 shows a control table for maintaining an interrupt request in the second embodiment of the present invention. The control table is provided corresponding to the PM (#) and comprises LDVC and PMIC. An LDVC comprises a table for managing interrupt requests from respective DVCs to a single PM by entering them into a queue in the arriving sequence. PMIC comprises a table for managing the sequence of the process of the interrupt requests when the interrupt requests from a plurality of DVCs arrive at a plurality of PMs. Figure 17 shows an example of a queue of the LDVC. In this case, interrupt request from DVCs to a PM#0 arrive at an ADP in the sequence DVC#2, DVC#0 and DVC#1. Therefore, as shown in Figure 17, a queue in which DVC#2, DVC#0 and DVC#1 are linked in sequence beginning with DVC#2 is formed for LDVC#0. LDVC#0 is subjected to PMIC#0 and PMIC#0 is activated when PMIC#0 reaches a head of a queue of PMIC and comes in an executing state. At this time, interrupt request DVC#2, which is provided at the head of the queue of PMIC#0, comes in an executing state and interrupt requests DVC#0 and DVC#1 come in a state of waiting for an execution. When an execution of the interrupt request from DVC#2 is completed, a request of DVC#2 is removed from the LDVC queue and instead DVC#0 comes to the head of the LDVC queue. However, at this time, PMIC#0 is removed from the head of the PDVC queue and is made to wait for an execution. Therefore, the interrupt request of DVC#0 is kept waiting for an execution until PMIC#0 comes in the next executing state. A format and state of the LDVC used regarding the interrupt request are the same as described above with regard to the I/O command. Figure 18 designates a format of the PMIC. PMIC has the following states. IDLE: This status shows that LDVC awaiting an interruption and belonging to a particular PM does not exist, i.e. in the state of IRQW (Interrupt Request Wait)/IRQ (Interrupt Request Execute) WAIT: This state shows that LDVC of IACKW (Interrupt Acknowledge Wait) exists and PMIC waits for an availability of AIBC23. IACKW designates a state in which an interrupt request is accepted by PM and IACK is awaited. ACTIVE: This state shows that the PM has a right to control AIBC23. The head LDVC connected to the PMIC is in the state of IRQEX. The PMIC has the machine number of DVC of the interrupt request source (Active LDVC#) and the link information (Next PMIC and Prev.PMIC) for connecting the PMIC to the next or previous PMIC to form a queue. Figure 19 shows an example of the interrupt queue of the PMIC. Interrupt requests from DVC#0, DVC#1 and DVC#2 are issued to PM#0, PM#1 and PM#2 and are maintained in the LDVC. PMIC#2, PMIC#0 and PMIC#1 are connected to a queue in this order in accordance with an arriving sequence of interrupt requests. The LDVC of DVC #0 forms a queue for PMIC #1. LDVCs of DVC#1, DVC#2 and DVC#0 form a queue for PMIC#0 and LDVC of DVC#0 forms a queue for PMIC#1. Figures 20 and 21 show flowcharts of the interruption process. As shown in Figure 20, an interruption process 1 first determines the state of PMICM when PMICm is Idle. Then the process determines the length of a PMIC interrupting queue. When the length of the queue is not 0, the state of PMIC is made Wait and PMIC enters the PMIC queue. Then the state of LDVCmn is made IRQW and is connected to the LDVC interruption queue of PMICn. When the length of the PMIC interrupting queue is 0, the state of PMIC is made ACTIVE and PMIC is connected to the head of the PMIC queue. Then the state of LDVCmn is made IRQEX. Next, PMIC enters a head of the LDVC interruption queue of PMICn. The process asks AIBC to issue an interruption command. Then the process returns to I/O instruction execution. When the state of PMICM is Wait or ACTIVE, the process turns directly the state of LDVCnm to IRQW. Interruption process 2 is activated by an interrupt from AIBC to APU 21 and by notification of a result of an interrupt bus command. As shown in Figure 21, interruption process 2 determines the result of an execution of an interruption bus command. When the interruption bus command execution is accepted, the state of LDVC at the head is IACKW and is removed from the LDVC interrupt queue. When the length of the LDVC interrupt queue is 0, the state of PMIC is made Idle and the PMIC is removed from the PMIC queue. Then the process determines the length of the PMIC interrupt queue. When the length of the PMIC interrupt queue is not 0, the state of the next PMIC is made ACTIVE and the LDVC at the head is made IRQEX. Then the process instructs AIBC to issue an interrupt command, thereby returning to the original process. When the length of the PMIC interrupt queue is 0, the process is directly returned to the original one. When the length of the LDVC interrupt queue is not 0, the state of PMIC is made WAIT and the state of LDVC is made IRQW and is changed to be connected to the end of the PMIC queue. When the result of the interrupt bus command execution is rejection, the state of PMIC is also made WAIT, and the state of LDVC is made IRQW and is changed to be connected to the end of the PMIC queue. According to the present invention, as is described above, respective PMs can directly determine an access path to a discretional DVC through an ADP without going through other PMs and it is not necessary for the PM issuing input/output request to reissue the input/output request even if the DVC to which an access is made is being used and it is also not necessary to communicate with other PMs, thereby decreasing an overhead and increasing a performance of a multi-processor system. Further, the present invention can decrease an occurrence of a state of waiting for an interrupt to other PMs depending on whether the interrupt to a particular PM is accepted, when the interrupt request from respective DVCs to the PM is processed, thereby preventing the processing performance of a multi-processor system from being decreased.

Claims: A multi-processor system comprising an input/output request control arrangement, said arrangement comprising: a plurality of input/output adapters (ADP) (2); a plurality of input/output devices (DVC) (3); and a plurality of information processing modules (PM); and characterised in that the plurality of information processing modules (PM) are for using the input/output adapters (ADP) (2) and in that the input/output devices (DVC) (3) are divided to be controlled by respective input/output adapters; and further comprising: means for providing a logical input/output request holding table (LDVC) (221) for managing input/output requests from respective information processing modules for each of said input/output devices (DVC) (3) controlled by said information processing modules by using a drive queue; and means for processing input/output requests from respective information processing modules (1) based on a state of said input/output request maintaining table and the input/output devices. A multiprocessor system according to claim 1, wherein physical input/output request holding tables (PDVCs) are provided in accordance with said DVCs (3) and said PDVCs form a PDVC drive queue in the order of access to a device bus (DVBUS) (5). The multi-processor system according to claim 1, wherein said input/output request maintaining table stores input/output requests from a plurality of PMs to the same DVC (3) in respective cells of a row corresponding to the same DVC (3), thereby enabling said cells to form an LDVC drive queue in a predetermined order. The multi-processor system according to claim 3, wherein PDVCs are provided corresponding to said respective DVCs (3), the DVCs (3) corresponding to respective rows of said input/output request maintaining table are controlled by a PDVC queue, and when the LDVC reaches the head of the LDVC queue, the LDVC at the head of the LDVC queue enters the PDVC queue and when the PDVC comes to the head of the PDVC queue, an execution of the input/output starts, whereby the input/output request is executed when the input/output request reaches the head of the LDVC drive queue and further reaches the head of the PDVC queue. The multi-processor system according to claim 4, wherein the states of said LDVC comprise IDLE, in which nothing is done; WAIT, in which the availability of PDVC is awaited; WORK, in which the LDVC comes to the head of the queue an executes the input/output operation; IRQW, in which LDVC is entered into the interrupt queue and waits its turn to issue an IRQ bus command; IRQEX, in which LDVC is connected to the head of interrupt queue, PMIC (PM Interruption Control Table) is connected to the head of a PMIC interrupt queue, an IRQ bus command is issued and notification of acceptance by PM (1) is awaited; and IACKW (Interrupt Acknowledge Wait), in which the interrupt request is accepted by the PM (1) and the IACK bus command is awaited by ADP (2), whereby the input/output request is associated with the interrupt request relating to a completion of an execution of the input/output request. The multi-processor system according to claim 4, wherein said PDVC comprises IDLE, in which nothing is done; WAIT, in which the availability of DVBUS is awaited; WORK, in which the input/output operation is executed; and DISC, in which the DVC is operating and the DVBUS (5) is disconnected. The multi-processor system according to claim 4, wherein said ADP (2) comprises means for accepting an input/output command when the input/output command arrives, means for executing an input/output command when the input/output command does not arrive or when a PDVC in a WAIT state exits upon a completion of acceptance of the input/output command and for performing an interrupt operation to the PM (1) upon completion of an input/output operation, and means for performing a reconnection process when the PDVC in a WAIT state does not exist or when the reconnection request is made upon an execution of said input/output command. The multi-processor system according to claim 7, wherein said input/output request accepting means comprising means for rejecting an acceptance of an input/output request when IACK is not issued and LDVCnm is in a state other than IDLE, means for responding to PM by a completion of the input/output request receipt when IACK is not issued and LDVCnm is in an IDLE state, means for changing the state of LDVCmn to WAIT and adding LDVCmn to the LDVC queue, means for changing PDVCm to WAIT when PDVCm is in an IDLE state and adding PDVCm to PDVC drive queue, and means for making LDVCnm in an interrupt state IDLE when IACK is issued. The multi-processor system according to claim 7, wherein said input/output command executing means comprises means for changing the state of PDVCm to WORK when DVBUS is available and changing the state of LDVCm to WORK, means for executing an input/output operation, means for changing the state of PDVCm to DISC when the input/output operation is not completed and removing PDVCm from the PDVC queue, means for removing LDVCnm from LDVC drive queue and performing an interrupt process when all the input/output operations are completed, means for changing the state of PDVCm to IDLE when the length of the LDVC drive queue is 0 and removing PDVCm from said PDVC drive queue, and means for changing the state of PDVCm to WAIT when the length of the LDVC drive queue is not 0 and adding the PDVCm to the last of the PDVC drive queue. The multi-processor system according to claim 9, wherein said interrupt process comprises means for judging the length of a PMIC interrupt queue, means for connecting the interrupt request to the LDVC interrupt queue of the PMICn when the length of the PMIC interrupt queue is not 0 and means for connecting said interrupt request to the head of the PMIC queue and further connecting said interrupt request to the head of the LDVC interrupt queue of PMICn when the length of the PMIC interrupt queue is 0 and for instructing that an interrupt command be issued. The multi-processor system according to claim 9, wherein said interrupt process means comprises means for removing the LDVC at the head from the LDVC interrupt queue when the interrupt bus command is accepted, means for removing a PMIC from a PMIC queue when the length of the LDVC interrupt queue is 0, means for making the state of the next PMIC ACTIVE when the length of the PMIC interrupt queue is not 0, designating the LDVC at the head as IRQEX and issuing the interrupt command, means for returning to an original process when the length of the PMIC interrupt queue is 0 and means for connecting PMIC to the end of the PMIC queue when the interrupt bus command is not accepted or the length of the LDVC interrupt queue is not 0. A multi-processor system comprising an interrupt request control arrangement, said arrangement comprising: a plurality of input/output adapters (ADP); a plurality of input/output devices (DVC); and a plurality of information processing modules (PM) and characterised in that the information processing modules (PM) are for using the input/output adapters (ADP) and in that the input/output devices (DVC) are divided to be controlled by respective input/output adapters; and further comprising: means for providing an interrupt request maintaining table for managing interrupt requests from respective input/output devices to each of said information processing modules by using a queue; and means for processing interrupt requests of respective input/output devices based on the state of said interrupt request maintaining table and the input/output devices. The multi-processor system according to claim 12, wherein PM interruption control tables (PMIC)s are provided in accordance with said PMs and said PMICs form a PMIC interrupt queue in the order of access to the input/output bus IOBUS (4). The multi-processor control system according to claim 12, wherein said interrupt request maintaining table stores interrupt requests from a plurality of DVCs (3) to the same PM in respective cells of a row corresponding to the same PM, thereby enabling said cells to form a queue in a predetermined order. The multi-processor system according to claim 12, wherein PM interruption control tables (PMIC)s are provided corresponding to said respective PMs, said PMs corresponding to respective rows of said input/output request maintaining table are controlled by a PMIC queue, and when the LDVC reaches the head of the LDVC queue, the LDVC at the head of the LDVC queue enters the PMIC queue and when the PMIC comes to the head of the PMIC queue, an interrupt execution starts. The multi-processor system according to claim 15, wherein the state of said LDVC comprises IDLE, in which nothing is done; WAIT, in which the availability of PDVC is awaited; WORK, in which the LDVC comes to the head of the queue and executes the input/output operation; IRQW (Interrupt Request Wait), in which LDVC is entered into the interrupt queue and awaits its turn to issue an IRQ bus command; IRQEX, in which LDVC is connected to the head of interrupt queue, PMIC is connected to the head of PMIC interrupt queue, an IRQ bus command is issued and notification of acceptance by PM is awaited; and IACKW, in which the interrupt request is accepted by the PM (1) and the IACK (Interrupt Acknowledge) bus command is awaited by ADP (2). The multi-processor system according to claim 15, herein said PDVC comprises IDLE, in which nothing is done; WAIT, in which the availability of DVBUS (5) is awaited; and WORK, in which the input/output operation is being executed. The multi-processor system according to claim 12, wherein said interrupt process comprises means for judging the length of the PMIC interrupt queue when the state of PMIC is IDLE, means for making the state of PMIC WAIT, connecting the interrupt request to PMIC queue and connecting the interrupt request to the LDVC interrupt queue of the PMICn when the length of the PMIC interrupt queue is not 0, means for connecting said interrupt request to the head of PMIC queue and further connecting said interrupt request to the head of LDVC interrupt queue of PMICn when the length of PMIC interrupt queue is 0 and for instructing that an interrupt command be issued and means for connecting said interrupt request to an LDVC interrupt queue of PMICn when the state of PMICn is WAIT or ACTIVE. The multi-processor system according to claim 12, wherein said interrupt process means comprises means for removing the LDVC at the head from the LDVC interrupt queue when the interrupt bus command is accepted, means for removing a PMIC from PMIC queue when the length of LDVC interrupt queue is 0, means for making the state of the next PMIC ACTIVE when the length of the PMIC interrupt queue is not 0, making the LDVC at the head IRQEX and issuing the interrupt command, means for returning to an original process when the length of the PMIC interrupt queue is 0 and means for connecting PMIC to the end of the PMIC queue when the interrupt bus command is not accepted or the length of the LDVC interrupt queue is not 0.

Inventors: KIMURA MAKOTO, KIMURA, MAKOTO
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1991
Main classification: G06F15
IPC codes: G06F13, G06F15