Information processing system comprising a main memory having an area for memorizing a state signal related to a diagnosing operation

Abstract: In an information processing system comprising a diagnosing unit (15) for carrying out, in response to an activation signal (17), a diagnosing operation on a main memory (10), a standard processor (11 or 12), and a system controller (13), a state indication area (20) memorizes a state signal which is produced by a monitoring unit (18) monitoring the diagnosing unit to indicate whether the diagnosing operation is possible and impossible and which, when the diagnosing operation is impossible, makes a diagnosis control unit (19) control retry of the diagnosing operation. Through a request controller (27) operable as a read request supply unit, the state signal is read by a read request signal produced by a signal producing unit (21) to make a judging unit (29) make a delivery control unit (24) allow and inhibit, when the diagnosing operation is possible and impossible, delivery as the activation signal of a communication signal produced by the signal producing unit through a communication controller (25) operable as a communication request supply unit. The state signal is stored in the state indication area by a write request signal produced by the signal producing unit and sent through the request controller which is now operable as a write request controller.

Description: This invention relates to an information processing system comprising a main memory, at least one standard processor, a system controller, and a diagnostic processor. The standard processor is, for example, a control processor, an arithmetic processor, or the like. In an information processing system of the type described, the diagnostic processor comprises a diagnosing unit connected to the main memory, the standard processor, and the system controller. The diagnosing unit carries out a diagnosing operation on the main memory, the standard processor, and the system controller in response to an activation signal. Connected to the diagnosing unit, a monitoring unit detects a failure in the diagnosing unit, namely, monitors the diagnosing unit to produce a state signal indicative of whether or not the diagnosing unit can carry out the diagnosing operation. Connected to the diagnosing unit and the monitoring unit, a diagnosis control unit carries out a controlling operation of restart or retry of the diagnosing operation in response to the state signal when the state signal indicates that the diagnosing unit can not deal with the diagnosing operation. Such a controlling operation of retry of the diagnosing operation will later be described. It will be assumed that the information processing system comprises first and second standard processors. Each of the first and the second standard processors can put the diagnosing unit into a normal state of carrying out the diagnosing operation by sending, as the activation signal, a communication request signal to the diagnosing unit through the system controller. For example, the communication request signal is sent to inform the diagnosing unit that a failure occurs in the standard processor in question. Alternatively, the communication request signal is sent to make a request for log-out which is known in the art. It will also be assumed that the diagnosing unit is put in the normal state by a first communication request signal sent by the first standard processor and that the monitoring unit finds a failure to put the diagnosis control unit into the controlling operation of retry of the diagnosing operation. In this event, the diagnosing unit is temporarily put in an interrupted state of interrupting the diagnosing operation. It will furthermore be assumed that the second standard processor sends, as the activation signal, a second communication request signal to the diagnosing unit through the system controller while the diagnosing unit is kept in the interrupted state. In a conventional information processing system, the system controller reserves, in such a case, the second communication request without delivering the second communication request signal from the system controller to the diagnostic processor until the diagnosing operation is fully retried. In many cases, the second standard processor can not receive a reply communication signal from the diagnosing unit through the system controller within a predetermined time duration after the second communication request signal is sent to the system controller. Therefore, the second standard processor is subjected to a time-out error. This puts the information processing system into system down. In US-A- 3 876 987, a multiprocessor system is described in which any of the processors in the system can request a diagnostic operation. Said diagnostic operation to be carried out by any other one of the processors in the system. The features of the system described in US-A- 3 876 987 are not directly comparable with the features of the system underlying the application, because the features of, as well as the problem solved by the present application, are closely related to the use of a dedicated diagnostic processor that is solely responsible for carrying out the diagnostic operation in the system. It is therefore an object of this invention to provide an information processing system which is not subjected to system down even when a diagnostic processor carries out retry of a diagnosing operation thereof. It is another object of this invention to provide an information processing system of the type described, which is capable of effectively making use of a time-out error occurred in a standard processor when a diagnostic processor carries out retry of a diagnosing operation thereof. These objects are solved with the features of the claims. The invention is further explained in connection with the drawings. Fig. 1 is a block diagram of an information processing system according to an embodiment of this invention; Fig. 2 is a time chart for use in describing operation of the information processing system illustrated in Fig. 1; Fig. 3 is another time chart for use in describing another operation of the information processing system illustrated in Fig. 1; and Fig. 4 is still another time chart for use in describing still another operation of the information processing system illustrated in Fig. 1. Referring to Fig. 1, an information processing system according to a preferred embodiment of this invention comprises a main memory 10, a control processor 11, an arithmetic processor 12, a system controller 13, and a diagnostic processor 14. Each of the control and the arithmetic processors 11 and 12 is herein referred to as a standard processor. The diagnostic processor 14 comprises a diagnosing unit 15 which is connected to the main memory 10, the control processor 11, the arithmetic processor 12, and the system controller 13 through a diagnostic bus 16. In response to an activation signal 17 which will later be described, the diagnosing unit 15 carries out a diagnosing operation on the main memory 10, the control processor 11, the arithmetic processor 12, and the system controller 13. Connected to the diagnosing unit 15, a monitoring unit 18 monitors the diagnosing unit 15 and produces a state signal indicative of whether or not the diagnosing unit 15 is capable of carrying out the diagnosing operation. More specifically, when the monitoring unit 18 detects a failure in the diagnosing unit 15, the monitoring unit 18 produces the state signal indicating that the diagnosing unit 15 is not capable of carrying out the diagnosing operation. Connected to the diagnosing unit 15 and the monitoring unit 18, a diagnosis control unit 19 controls retry of the diagnosing operation in response to the state signal indicating that the diagnosing unit 15 is not capable of carrying out the diagnosing operation. More specifically, the restart of the diagnosing operation is carried out as follows. The diagnostic control unit 19 saves data indispensable for a retry of the diagnosing unit 15 in a save area (not shown) as saved data at first. Subsequently, initialization is carried out for the diagnosing unit 15. Thereafter, restart of the diagnosing unit 15 is carried out. When the diagnosing unit 15 is thereby put into a state in which the retry can be made, the retry is actually carried out by using the saved data. The main memory 10 comprises a state indication area 20 connected to the monitoring unit 18 in the manner which will become clear as the description proceeds. The state indication area 20 memorizes the state signal as a state indication signal. The control processor 11 comprises a signal producing unit 21 which produces a communication request signal 22 and a read request signal 23. Connected to the signal producing unit 21, a communication control unit 24 of the control processor 11 receives the communication request signal 22 and controls delivery of the communication request signal 22 outwardly of the communication control unit 24. Thus, the communication control unit 24 of the control processor 11 serves as a delivery control unit. Connected to the signal producing unit 21, the delivery control unit controls delivery of the communication request signal 22 from the deliery control unit. The system controller 13 comprises an interprocessor communication controller 25 which is connected to the diagnosing unit 15 through a communication control unit 26 of the diagnostic processor 14 and is connected to the communication control unit 24 of the control processor 11 directly. The interprocessor communication controller 25 supplies the communication request signal 22 delivered from the communication control unit 24 of the control processor 11 to the diagnosing unit 15 as the activation signal 17. Thus, the interprocessor communication controller 25 serves as a communication request supply unit connected to the diagnosing unit 15 for supplying the communication request signal 22 delivered from the communication control unit 24 to the diagnosing unit 15 as the activation signal 17. Connected to the state indication area 20 directly and to the signal producing unit 21 through a main memory access controller 28 of the control processor 11, a main memory request controller 27 supplies the read request signal 23 to the state indication area 20 to receive the state indication signal as a read-out state signal through the main memory access controller 28. Thus, the main memory request controller 27 acts as a read request supply unit which supplies the state indication area 20 with the read request signal 23 to receive the state indication signal as the read-out state signal. The control processor 11 further comprises a judging unit 29 which is connected to the communication control unit 24 of the control processor 11 directly and to the main memory request controller 27. The judging unit 29 judges the read-out state signal and produces first and second control signals when the read-out state signal indicates that the diagnosing unit 15 is and is not capable of carrying out the diagnosing operation, respectively. The judging unit 29 sends the first and the second control signals to the communication control unit 24 of the control processor 11 to allow and inhibit the delivery of the communication request signal 22 towards the interprocessor communication controller 25, respectively. The arithmetic processor 12 is similar in structure and in operation to the control processor 11. Turning to Fig. 2 with reference to Fig. 1 continued, description will be made as regards operation of the information processing system illustrated in Fig. 1. Although description will now be made only about an interprocessor communication operation from the control processor 11 to the diagnostic processor 14, another interprocessor communication operation from the arithmetic processor 12 to the diagnostic processor 14 is carried out in the manner similar to the interprocessor communication operation from the control processor 11 to the diagnostic processor 14. It will be assumed that the signal producing unit 21 of the control processor 11 produces the communication request signal 22 and the read request signal 23 and that the communication control unit 24 of the control processor 11 receives the communication request signal 22 and controls delivery of the communication request signal 22 from the communication control unit 24. At a first stage S1, the main memory access controller 28 of the control processor 11 receives the read request signal 23 and sends the read request signal 23 to the main memory request controller 27. The first stage S1 proceeds to a second stage S2. At the second stage S2, the memory request controller 27 receives the read request signal 23 and supplies the state indication area 20 of the main memory 10 with the read request signal 23. The second stage S2 is succeeded by a third stage S3. At the third stage S3, the state indication area 20 of the main memory 10 receives the read request signal 23 and sends the state indication signal to the main memory request controller 27. For example, the state indication area 20 has one byte length. When the state indication signal has a hexadecimal value "00", the state indication signal indicates that the diagnosing unit 15 is capable of carrying out the diagnosing operation. When the state indication signal has another hexadecimal value "FF", the state indication signal indicates that the diagnosing unit 15 is not capable of carrying out the diagnosing operation. The third stage S3 is followed by a fourth stage S4. At the fourth stage S4, the main memory request controller 27 receives the state indication signal as a read-out state signal and sends the read-out state signal to the judging unit 29 through the main memory access controller 28 of the control processor 11. The fourth stage S4 is succeeded by a fifth stage S5. At the fifth stage S5, the judging unit 29 judges the read-out state signal and produces the first and the second control signals when the read-out state signal indicates that the diagnosing unit 15 is and is not capable of carrying out the diagnosing operation, respectively. More specifically, the judging unit 29 produces the first and the second control signals when the read-out state sgnal has the hexadecimal values "00" and "FF", respectively. The judging unit 29 sends the first and the second control signals to the communication control unit 24 of the control processor 11 to allow and inhibit the delivery of the communication request signal 22 towards the interprocessor communication controller 25, respectively. That is, the communication control unit 24 delivers the communication request signal 22 to the interprocessor communication controller 25 when the communication control unit 24 receives the first control signal. When the communication control unit 24 receives the second control signal, the communication control unit 24 reserves the communication request signal 22 without delivering the communication request signal 22 from the communication control unit 24 to the interprocessor communication controller 25. At a sixth stage S6 which follows the fifth stage S5, the interprocessor communication controller 25 receives the communication request signal 22 and supplies the communication request signal 22 to the diagnosing unit 15 through the communication control unit 26 of the diagnosing processor 14 as the activation signal 17. A seventh stage S7 follows the sixth stage S6. At the seventh stage S7, the diagnosing unit 15 carries out the diagnosing operation in response to the activation signal 17. More specifically, the diagnosing unit 15 decodes the communication request signal 22 into a decoded signal which specifies a specific one of diagnosing programs. Thereafter, the diagnosing unit 15 carries out a specific diagnosing operation in accordance to the specific program. When the diagnosing unit 15 finishes the specific diagnosing operation, the diagnosing unit 15 produces a reply communication signal as an end report of the specific diagnosing operation. The diagnosing unit 15 sends the reply communication signal to the interprocessor communication controller 25 through the communication control unit 26 of the diagnostic processor 14. At an eighth stage S8 which succeeds the seventh stage S7, the interprocessor communication controller 25 receives the reply communication signal and sends the reply communication signal to the communication control unit 24 of the control processor 11. Turning to Fig. 3 with reference to Fig. 1 continued, description will be made as regards a writing operation of writing the state signal in the state indication area 20. It will be assumed that the monitoring unit 18 detects, at a first stage S′1 indicated by a cross, a failure in the diagnosing unit 15 and produces an abnormal state signal indicating that the diagnosing unit 15 is not capable of carrying out the diagnosing operation. The first stage S′1 is followed by second and third stages S′2 and S′3. At the second stage S′2, the diagnosis control unit 19 controls retry of the diagnosing operation in response to the abnormal state signal. At the third stage S′3, the diagnosis control unit 19 produces, in response to the abnormal state signal, a write request signal and delivers the write request signal together with the abnormal state signal to the main memory request controller 27 of the system controller 13 through a main memory access controller 30 of the diagnostic processor 14. The third stage S′3 is succeeded by a fourth stage S′4. At the fourth stage S′4, the main memory request controller 27 supplies the write request signal and the abnormal state signal to the state indication area 20 of the main memory 10 to write the abnormal state signal in the state indication area 20 as the state indication signal. That is, the hexadecimal value "FF" is memorized in the state indication area 20 instead of the hexadecimal value "00" as depicted along a top line. At a fifth stage S′5 which succeeds the second stage S′2, the diagnosis control unit 19 of the diagnostic processor 14 finishes the retry of the diagnosing operation. In this event, the monitoring unit 18 of the diagnostic processor 14 produces a normal state signal indicating that the diagnosing unit 15 is capable of carrying out the diagnosing operation. When the diagnosis control unit 19 completes the retry of the diagnosing operation, the diagnosis control unit 19 produces first and second communication request signals to inform the control and the arithmetic processors 11 and 12 about an end of the retry, respectively. The diagnosis control unit 19 delivers not only the first communication signal directed to the control processor 11 but also the normal state signal to the interprocessor communication controller 25 of the system controller 13 through the communication control unit 26 of the diagnostic processor 14. Simultaneously, the diagnosis control unit 19 delivers the second communication request signal directed to the arithmetic processor 12. At a sixth stage S′6 which follows the fifth stage S′5, the interprocessor communication controller 25 of the system controller 13 supplies the first communication request signal and the normal state signal to the control processor 11. Simultaneously, the interprocessor communication controller 25 supplies the second communication request signal to the arithmetic processor 12. The control processor 11 receives the first communication request signal and the normal state signal and, thereby, knows the end of the retry of the diagnosing operation. When the arithmetic processor 12 receives the second communication request signal, the arithmetic processor 12 knows the end of the diagnosing operation. At a seventh stage S′7 which follows the sixth stage S′6, the signal producing unit 21 of the control processor 11 receives the first communication request signal and the normal state signal through the communication control unit 24. In response to the first communication request signal, the signal producing unit 21 produces a write request signal and delivers the write request signal together with the normal state signal to the main memory request controller 27 of the system controller 13 through the main memory access controller 28 of the control processor 11. The seventh stage S′7 is succeeded by an eighth stage S′8. At the eighth stage S′8, the main memory request controller 27 supplies the write request signal and the normal state signal to the state indication area 20 of the main memory 10 to write the normal state signal in the state indication area 20 as the state indication signal. That is, the hexadecimal value "00" is memorized in the state indication area 20 instead of the hexadecimal value "FF" as depicted along the top line. Turning to Fig. 4 with reference to Fig. 1 continued, description will proceed to another writing operation. It will be presumed that the signal producing unit 21 of the arithmetic processor 12 delivers a communication signal to the interprocessor communication controller 25 of the system controller 13 through the communication control unit 24 at a first stage S″1. The communication signal is directed to the diagnostic processor 14. At a second stage S″2, a timer unit 40 of the arithmetic processor 12 starts a measuring operation of a predetermined time interval in response to the communication signal. The timer unit 40 produces a time-out signal when the timer unit 40 can not receive a reply communication signal from the diagnostic processor 14 within the predetermined time duration. It will also be presumed that the monitoring unit 18 of the diagnostic processor 14 detects a failure in the diagnosing unit 15 immediately after the arithmetic processor 12 delivers the communication signal towards the system controller 13 at a third stage S″3. The monitoring unit 18 thereby produces the abnormal state signal indicating that the diagnosing unit 15 is not capable of carrying out the diagnosing operation. The third stage S″3 is followed by a fourth stage S″4. At the fourth stage S″4, the diagnosis control unit 19 of the diagnostic processor 14 controls retry of the diagnosing operation in response to the abnormal state signal. When the communication control unit 26 of the diagnostic processor 14 receives the communication signal through the interprocessor communication controller 25 during the fourth stage S″4, the communication control unit 26 makes the communication signal become invalid. More specifically, the diagnosis control unit 19 delivers an invalidation instruction signal to the communication control unit 26 while the diagnosis control unit 19 controls the retry of the diagnosing operation. In accordance with the invalidation instruction signal, the communication control unit 26 renders the communication signal invalid. Attention will be directed to the second stage S″2. Inasmuch as the communication signal is not supplied to the diagnosing unit 15, the diagnostic processor 14 never produces the reply communication signal. Therefore, the timer unit 40 of the arithmetic processor 12 can not receive the reply communication signal within the predetermined time duration and produces the time-out signal at the second stage S″2. The second stage S″2 is succeeded by a fifth stage S″5. At the fifth stage S″5, the signal producing unit 21 of the arithmetic processor 12 produces, in response to the time-out signal, a write request signal and the abnormal state signal and delivers the write request signal and the abnormal signal to the main memory request controller 27 of the system controller 13 through the main memory access controller 28 of the arithmetic processor 12. At a sixth stage S″6 which follows the fifth stage S″5, the main memory request controller 27 supplies the write request signal and the abnormal state signal to the state indication area 20 of the main memory 10 to write the abnormal state signal in the state indication area 20 as the indication signal. That is, the hexadecimal value "FF" is memorized in the state indication area 20 instead of the hexadecimal value "00" as depicted along a top line. At a fourth stage S″4 which succeeds the second stage S″4, the diagnosis control unit 19 of the diagnostic processor 14 finishes the retry of the diagnosing operation. In this event, the monitoring unit 18 of the diagnostic processor 14 produces a normal state signal indicating that the diagnosing unit 15 is capable of carrying out the diagnosing operation. When the diagnosis control unit 19 completes the retry of the diagnosing operation, the diagnosis control unit 19 produces first and second communication request signals to inform the control and the arithmetic processors 11 and 12 about an end of the retry, respectively. The diagnosis control unit 19 delivers not only the first communication signal directed to the control processor 11 but also the normal state signal to the interprocessor communication controller 25 of the system controller 13 through the communication control unit 26 of the diagnostic processor 14. Simultaneously, the diagnosis control unit 19 delivers the second communication request signal directed to the arithmetic processor 12. At an eighth stage S″8 which follows the seventh stage S″7, the interprocessor communication controller 25 of the system controller 13 supplies the first communication request signal and the normal state signal to the control processor 11. Simultaneously, the interprocessor communication controller 25 supplies the second communication request signal to the arithmetic processor 12. The control processor 11 receives the first communication request signal and the normal state signal and, thereby, knows the end of the retry of the diagnosing operation. When the arithmetic processor 12 receives the second communication request signal, the arithmetic processor 12 knows the end of the diagnosing operation. At a ninth stage S″9 which follows the eighth stage S″8 for the control processor 11, the signal producing unit 21 of the control processor 11 receives the first communication request signal and the normal state signal through the communication control unit 24. In response to the first communication request signal, the signal producing unit 21 produces a write request signal and delivers the write request signal together with the normal state signal to the main memory request controller 27 of the system controller 13 through the main memory access controller 28 of the control processor 11. The ninth stage S″9 is succeeded by a tenth stage S″10. At the tenth stage S″10, the main memory request controller 27 supplies the write request signal and the normal state signal to the state indication area 20 of the main memory 10 to write the normal state signal in the state indication area 20 as the state indication signal. That is, the hexadecimal value "00" is memorized in the state indication area 20 instead of the hexadecimal value "FF" as depicted along the top line.

Claims: An information processing system comprising a main memory (10), a standard processor (12), a system controller (13), and a diagnostic processor (14) comprising: diagnosing means (15) connected to said main memory (10), said standard processor (12), and said system controller (13) for carrying out a diagnosing operation on said main memory (10), said standard processor (12), and said system controller (13) in response to an activation signal (17); monitoring means (18) connected to said diagnosing means (15) for monitoring said diagnosing means (15) to produce a state signal indicative of whether or not said diagnosing means (15) is capable of carrying out said diagnosing operation; and diagnosis control means (19) connected to said diagnosing means (15) and said monitoring means (18) for controlling retry of said diagnosing operation in response to the state signal indicating that said diagnosing means (15) is not capable of carrying out said diagnosing operation; said main memory (10) comprising a state indication area (20) operatively connected to said monitoring means (15) for memorizing said state signal as a state indication signal; said standard processor (12) comprising: signal producing means (21) for producing a communication request signal (22) and a read request signal (23); and delivery control means connected to said signal producing means for controlling delivery of said communication request signal (22) from said delivery control means; said system controller (13) comprising: communication request supply means connected to said diagnosing means (15) and said delivery control means for supplying the communication request signal (22) delivered from said delivery control means to said diagnosing means (15) as said activation signal (17); and read request supply means (27) connected to said state indication area (20) and said signal producing means (21) for supplying said state indication area (20) with said read request signal (23) to receive said state indication signal as a read-out state signal; said standard processor (12) further comprising judging means (29) connected to said delivery control means and said read request supply means for judging said read-out state signal to produce first and second control signals when said diagnosing means (15) is and is not capable of carrying out said diagnosing operation, respectively, said judging means (29) sending said first and said second control signals to said delivery control means to allow and inhibit said delivery, respectively.

Inventors: IWATA JUN C O NEC CORPORATION, IWATA, JUN C/O NEC CORPORATION
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1990
Main classification: G06F11
IPC codes: G06F11, G06F15