JP3266042B2 - Bus control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus control system and, more particularly, to an American National Standards Institute ANSI (American).
National Standard Institute
te) defines SCSI (Small Computing)
The present invention relates to a target operation SCSI controller which has an interface of an er System Interface, and executes a SCSI bus operation when a central processing unit in a main unit issues a control instruction.

[0002]

2. Description of the Related Art Conventionally, in a system using a SCSI bus, it has been defined that a SCSI controller (hereinafter referred to as a target) operating as a target controls a bus phase transition for performing data transfer or the like. I have.

In this case, if the target stalls for some reason during the operation of the SCSI bus, a SCSI controller (hereinafter, referred to as an initiator) operating as an initiator cannot perform control for shifting the bus phase.
Bus lock may occur.

[0004] For this reason, the initiator monitors the transition of the bus phase by a timer, and if the phase does not transition within a predetermined time, a SCSI RESET signal (hereinafter, referred to as a command hereinafter) instructs a device connected to the SCSI bus to reset.
There is a method (apparatus) in which the initiator is provided with a timer monitoring function for preventing the bus lock by transmitting a reset signal) and preventing a decrease in bus use efficiency during the bus lock period.

For example, in an initiator, SCSI
There is a method of monitoring an execution time of a data phase in a bus and performing an error recovery process such as sending a reset signal when the data phase does not end within a predetermined time. This method is disclosed in JP-A-5-128045.

Further, the phase transition time on the SCSI bus is monitored, and if the phase does not transition at a predetermined time, it is determined that a bus lock has occurred and a reset signal is transmitted. There is a way to notify. This method is disclosed in JP-A-4-280.
No. 339.

[0007]

In the conventional bus control method described above, in many cases, a device having a bus phase timer monitoring function has a timer value unique to each device. Considering them as a whole system, including the configuration of the device to which the device is connected and the amount of job processing, etc., the timer value is not set to a monitoring time that matches the system configuration. Problems may occur.

In other words, when a central processing unit issues a control command to execute a SCSI bus operation and the above-described device having a timer monitoring function is connected to perform data transmission / reception, If the load on the main unit to which the is connected is temporarily increased, for example, if the issuance interval of the control instruction issued from the central processing unit to the target becomes longer than usual, the bus operation of the target becomes slow. As a result, the transfer may not be completed within the timer monitoring time of the bus phase performed by the partner device, and a reset signal is sent each time the phenomenon occurs.

For this reason, when the load on the main unit connected to the target increases, a period occurs in which unnecessary reset signals are frequently transmitted, and every time the reset signal is transmitted, a period on the SCSI bus increases. Must perform a reset process, and the usage efficiency of the SCSI bus becomes very poor.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to prevent unnecessary reset signals from being transmitted due to the load state of the main unit, and to improve the use efficiency of the SCSI bus. A bus control system is provided.

[0011]

Bus control system according to the invention According to an aspect of the the initiator, the target in which the initiator is selected, and a SCSI bus which connects the said initiator target, said initiator <br/> The execution time of the bus phase with the target is
The load varies with the load of the
Eta is a bus control system configured to delivering a reset signal when-time-out of the bus phase to the timer monitoring the bus phase on the SCSI bus, said in response to the identification information identifying the initiator Storage means for storing an effective time generated in advance based on the monitoring time of the timer monitoring; clocking means for clocking the execution time of the bus phase; and clocking time of the clocking means indicating the validity time. Means for temporarily suspending connection to the SCSI bus when the target is exceeded.

In another bus control system according to the present invention, in addition to the above-described configuration, holding means for holding information necessary for reconnection to the SCSI bus when connection to the SCSI bus is temporarily interrupted, Determining means for determining whether reconnection to the SCSI bus is possible after suspending connection to the SCSI bus; and holding means when the determination means determines that reconnection to the SCSI bus is possible. Means for reconnecting to the SCSI bus based on the information held in the target.

[0013] Another bus control system according to the invention is intended to perform a bus operation by a control command from the host apparatus
And the execution time of the bus operation is determined by the load of the host device.
A target varies with the initiator selects the target, and a SCSI bus which connects the said initiator targets, Thailand the bus phase bus phase with timer monitoring between the initiator to the target A bus control system configured to send a reset signal on the SCSI bus when the bus is out, storing a valid time generated in advance based on a monitoring time of the timer monitoring in correspondence with identification information for specifying the initiator. Storage means for performing the execution of the bus phase, and time-measuring means for measuring the execution time of the bus phase, and means for temporarily suspending the connection to the SCSI bus when the time-measurement time of the time-measuring means exceeds the valid time. I have.

Still another bus control system according to the present invention, in addition to the above-described configuration, includes a holding unit for holding information necessary for reconnection to the SCSI bus when the connection to the SCSI bus is temporarily suspended. Determining means for determining whether reconnection to the SCSI bus is possible after temporarily suspending the connection to the SCSI bus;
The target includes means for reconnecting to the SCSI bus based on information held in the holding means when it is determined that reconnection to the SI bus is possible.

That is, in the bus control system of the present invention, the target monitors the execution time of the bus phase with the timer, and when the time monitoring detects a timeout, the connection to the SCSI bus is temporarily suspended.

More specifically, in the target connected to the SCSI bus, the maximum in each information transfer phase (message out phase, message in phase, command phase, data phase, status phase) for each initiator's ID information. An execution time information section for storing execution time information; a timer section for measuring time; and monitoring of a SCSI bus state and comparing information set in the execution time information section with information from the timer section. A bus execution time monitoring unit for notifying the control instruction notifying unit of the detection of the timeout when a timeout is detected by the control unit, and a bus for the SCSI controller in response to the notification from the bus execution time monitoring unit for managing the control instruction A control command notification unit that has the function of issuing a command to suspend Eteiru.

Accordingly, even if the counter unit has a bus phase timer monitoring function and sends out a reset signal when the timer monitoring function detects a timeout, the load state of the main unit to which the target is connected is reduced. Regardless, before the time set by the timer value of the bus phase monitoring of the partner initiator reaches S
By temporarily suspending the CSI bus, it is possible to prevent the use efficiency of the SCSI bus from being lowered due to unnecessary reset signal transmission.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the figure, a system according to an embodiment of the present invention is configured by connecting a main unit 1 and SCSI control devices (hereinafter, referred to as initiators) 7-1 to 7-n operating as initiators to each other via a SCSI bus 100. ing.

The main unit 1 operates as a target S
The system includes a CSI control device (hereinafter referred to as a target) 2, a central processing unit 3, a main storage device 4, a bus interface unit 5, and input / output control devices 6-1 to 6-m.

The initiators 7-1 to 7-n perform information transfer phases (message out phase, message in phase, command phase,
It has a timer monitoring function for a data phase and a status phase, and sends a SCSI RESET signal (hereinafter, referred to as a reset signal) for instructing each device connected to the SCSI bus 100 to reset when the timer monitoring function detects a timeout. Send on 100.

The central processing unit 3, the main storage unit 4, and the bus interface unit 5 are connected to each other by a system bus 101, and the target 2, the bus interface unit 5, and the input / output control units 6-1 to 6-m are /
They are connected to each other by an O bus 102. That is, the system bus 101 and the general-purpose I / O bus 102 are connected through the bus interface unit 5.

The central processing unit 3 is an arithmetic unit of the main unit 1, and issues control commands to the target 2, the input / output control units 6-1 to 6-m, and the like. The main storage device 4 is an information storage unit and stores information necessary for the operation of the main device 1. The main storage device 4 also stores information such as data transmitted and received from the target 2 and the input / output control devices 6-1 to 6-m.

The bus interface unit 5 is a device that controls transmission and reception of information correctly between the system bus 101 and the general-purpose I / O bus 102, and includes the target 2 and the input / output control devices 6-1 to 6-1. 6-m is general purpose I /
It also manages arbitration when using the O bus 102.

The general-purpose I / O bus 102 is a bus to which various input / output control devices can be connected for m units.
The target 2 and the input / output control device 6 are connected to the / O bus 102.
1 to 6-m are connected.

The target 2 is a SCSI controller having a function of operating as a target. The target 2 performs an operation on the SCSI bus 100 in accordance with a control command issued from the central processing unit 3 and outputs the result to the central processing unit 3.
, The operation for the SCSI bus 100 is realized. The input / output control devices 6-1 to 6-m are other input / output control devices.

The target 2 has an execution time information section 21.
, A timer unit 22, a bus execution time monitoring unit 23, a control command management unit 24, and a SCSI controller 25.

Each of the initiators 7 is stored in the execution time information section 21.
Use permission time information in each information transfer phase preset based on the monitoring time of the timer monitoring function of each initiator 7-1 to 7-n is stored for each ID information for identifying -1 to 7-n. ing.

Note that the use permission time information is composed of timer monitoring valid information and valid time information. The timer monitoring validity information is provided for each information transfer phase.
This is information indicating invalidity.

The valid time information is information on the maximum time that can be executed for each information transfer phase, and its value is the destination initiator 7-1 to 7-n.
Is set to a value that is smaller than the monitoring time that the timer monitors for the bus phase that the device has, and that is longer than the normal execution time required when the bus operation is performed in the normal state in that phase. Also, the use permission time information is stored in the central processing unit 3 when the power of the main unit 1 is turned on.
Shall be written from

The timer unit 22 measures the time in each bus phase, and uses the measured time as the bus execution time monitoring unit 2
3 is sequentially notified. The bus execution time monitoring unit 2
It is reset by the reset notification from 3 and has a function to measure the time again.

The bus execution time monitoring unit 23 constantly monitors the status of the SCSI bus 100, and monitors the status of the initiator 7.
When -1 to 7-n select the target 2 as the partner device, the execution time information section 21 sends the initiator 7-1 to
Extract valid time information corresponding to 7-n.

In the target 2, a bus operation is performed by a control command from the central processing unit 3, and the bus phase does not transition unless a control command is issued. The bus execution time monitoring unit 23 sends a reset notification to the timer unit 22 every time the bus phase of the SCSI bus 100 changes.

If the current bus phase has the timer monitoring enabled by the timer monitoring validity information of the execution time information unit 21, the bus execution time monitoring unit 23 determines the value of the valid time information and the value of the measurement time of the timer unit 22. Compare. When the value of the measured time of the timer unit 22 exceeds the value of the valid time information, the bus execution time monitoring unit 23 notifies the control instruction management unit 24 that a timeout has occurred.

The control command management unit 24 manages the control commands. When there is no notification from the bus execution time monitoring unit 23, the control command issued from the central processing unit 3 is transmitted to the SCSI controller 25 via the signal line 214. To send to. However, when receiving the notification from the bus execution time monitoring unit 23, the control instruction management unit 24 performs the interruption processing of the currently executed control instruction, and after the interruption processing, the SCSI
It issues a control command to the controller 25 to temporarily suspend the connection to the SCSI bus 100.

Thereafter, the control command management unit 24 sets the main unit 1
When it is determined that the interrupted processing can be resumed based on the processing status of the SCSI bus 100 and the usage status of the SCSI bus 100, a control command requesting reconnection of the SCSI bus 100 is issued to the SCSI controller 25. The information saved in the interruption processing (for example, the address information at the time of interruption and the remaining data amount at the time of interruption) is restored, and the execution of the control instruction is resumed.

FIG. 2 is a diagram showing the configuration of the execution time information section 21 of FIG. In the figure, the execution time information section 21 includes a timer monitoring effective information section 21a and an effective time information section 21b.

The timer monitoring effective information section 21a stores each ID information (ID = 0, ID = 1) of the initiators 7-1 to 7-n.
1,..., ID = 7) store timer monitoring valid information [“0” (invalid), “1” (valid)] corresponding to each bus phase.

The valid time information section 21b stores valid time information corresponding to each bus phase, that is, valid time information a0 to a7 of a message out phase, valid time information b0 to b7 of a message in phase, and a command phase. Valid time information c0 to c7, valid time information d0 to d7 of the data phase, and valid time information e0 to e7 of the status phase are stored.

FIG. 3 is a flowchart showing the operation of the bus control according to one embodiment of the present invention. The operation of the bus control according to one embodiment of the present invention will be described with reference to FIGS. Here, for simplicity of description, the initiator 7-1 has a timer monitoring function in the bus phase, and is configured to send a reset signal when a time-out occurs. Function.

The bus execution time monitoring unit 23 always monitors the status of the SCSI bus 100, and the initiator 7-1
When the user selects the target 2 as the partner device in the selection phase, from the ID information (ID = 0) notified at the time of the selection, the use permission time information corresponding to the initiator 7-1 is executed by the signal line 211 through the execution time information. (Step S in FIG. 3)
1, S2). Thereafter, the control command management unit 24 sends the SCS
Execute the control instruction for the I bus operation (step S in FIG. 3)
3). The SCSI bus operation includes one including one control instruction and one including a plurality of control instructions.

The bus execution time monitoring unit 23 determines whether or not the current SCSI bus phase is a phase in which the timer monitoring is effective in executing the control instruction (step S in FIG. 3).
4). In this case, since the information ("1") indicating that only the data phase is valid is set in the timer monitoring validity information of the timer monitoring validity information section 21a, the bus execution time monitoring section 23 transits to the data phase. Until the timer is monitored.

The bus execution time monitoring unit 23 starts timer monitoring when it detects that a transition has been made to the data phase via the signal line 216, and the valid time information d 0 of the valid time information unit 21 b and the timer input from the signal line 212. The value is compared with the value of the measurement time of the unit 22 (step S5 in FIG. 3).

The bus execution time monitoring unit 23 determines that the value of the measurement time of the timer unit 22 is the valid time information d of the valid time information unit 21b.
When the value does not exceed 0, the control instruction ends (step S in FIG. 3).
5, S10), when the SCSI bus operation ends (step S11 in FIG. 3), the SCSI bus operation in the target 2 ends.

The bus execution time monitoring unit 23 uses the value of the measured time of the timer unit 22 as the valid time information d of the valid time information unit 21b.
When it is detected that the number has exceeded 0, the control command management unit 24 is notified of the timeout detection via the signal line 213 (FIG. 3).
Step S6).

When notified of the detection of the timeout from the bus execution time monitoring unit 23, the control instruction management unit 24 executes a process of interrupting the currently executed control instruction (step S3 in FIG. 3).
7). As the interruption processing, for example, after information necessary for re-execution is saved in a holding unit (not shown), the SCSI bus 10
SAV as a control instruction to suspend the connection to
E DATA POINTER message transmission and DI
Control command for sending SCONNECT message is SCSI
Processing such as transmission to the controller 25 is performed.

After that, the control command management unit 24
When it is determined that the interrupted processing can be restarted based on the processing status of the SCSI bus 100 and the usage status of the SCSI bus 100 (step S8 in FIG. 3), the control instruction is restarted (step S9 in FIG. 3). As this resuming process, for example, after issuing an execution of SCSI bus reconnection (RESELECTION) to the SCSI controller 25 as a control command of a bus reconnection request, the information saved in the suspending process is restored, and the control command is issued. For example, the processing of resuming the processing is performed. When the restarted control instruction ends (step S10 in FIG. 3) and the SCSI bus operation ends (step S11 in FIG. 3), the SCSI bus operation in the target 2 ends. If the SCSI bus operation is not completed (step S11 in FIG. 3), the process returns to step S3 to execute the next control instruction.

As described above, when the target 2 performs the bus operation, the bus execution time monitoring unit 23 compares the measurement time from the timer unit 22 with the valid time information from the execution time information unit 21 and determines that the measurement time is valid. The central processing unit 3 issues a control instruction by notifying the control instruction management unit 24 of timeout detection when the time information value is exceeded, and immediately suspending the connection to the SCSI bus 100 by the control instruction management unit 24 immediately. When the target 2 that executes the operation of the SCSI bus 100 is connected to the initiators 7-1 to 7-n that have a bus phase timer monitoring function and that send out reset signals when a timeout occurs, the main unit 1 Transmission of unnecessary reset signals from the initiators 7-1 to 7-n caused by the load condition of
The transfer efficiency of the SCSI bus 100 can be improved.

When the control command management unit 24 determines that the interrupted processing can be resumed based on the processing status of the main unit 1 and the usage status of the SCSI bus 100,
By restoring the information saved in the suspending process and reconnecting to the SCSI bus 100, unnecessary reset signals from the initiators 7-1 to 7-n caused by the load state of the main unit 1 are transmitted. Thus, the usage efficiency of the SCSI bus 100 can be improved.

[0049]

As described above, according to the bus control system of the present invention, the system includes the initiator, the target selected by the initiator, and the SCSI bus connecting the initiator and the target. In the target of the bus control system configured to monitor the bus phase and send a reset signal on the SCSI bus when the bus phase ties out, the target is set based on the monitoring time of the timer monitoring in association with the identification information specifying the initiator. When the time set by the timer means for counting the time of the bus phase exceeds the valid time, the connection to the SCSI bus is temporarily interrupted, thereby causing a load condition of the main unit. Unnecessary reset signal transmission can be prevented, and the SCSI There is an effect that it is possible to improve the use efficiency.

Further, according to another bus control system of the present invention, in the above-mentioned target, information necessary for reconnection to the SCSI bus when temporarily suspending connection to the SCSI bus is stored, and Unnecessary reset signal caused by the load condition of the main unit by reconnecting to the SCSI bus based on the information held when it is determined that reconnection to the SCSI bus is possible after suspending the connection to the bus. And the transmission efficiency of the SCSI bus can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an execution time information unit of FIG. 1;

FIG. 3 is a flowchart illustrating an operation of bus control according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main device 2 SCSI controller which operates as a target 3 Central processing unit 4 Main storage device 5 Bus interface unit 6-1-6-m I / O controller 7-1-7-n SCSI which operates as an initiator
Control device 21 Execution time information section 22 Timer section 23 Bus execution time monitoring section 24 Control command management section 25 SCSI controller 100 SCSI bus 101 System bus 102 General-purpose I / O bus

Claims (8)

(57) [Claims] 1. An initiator, a target selected by the initiator, and a SCSI bus connecting the initiator and the target, wherein the execution time of a bus phase between the initiator and the target is
Target load, which varies with the load of the target.
Initiator is said reset signal when-time-out of the bus phase to the timer monitoring the bus phase SCS
A bus control system configured to transmit data on an I bus, comprising: a storage unit configured to store a valid time generated in advance based on a monitoring time of the timer monitoring in accordance with identification information specifying the initiator; Bus control, characterized in that the target includes: a timing unit for timing the execution time of a bus phase; and a unit for temporarily suspending the connection to the SCSI bus when the timing time of the timing unit exceeds the valid time. system. 2. A holding means for holding information necessary for reconnecting to the SCSI bus when the connection to the SCSI bus is temporarily interrupted, and to the SCSI bus after temporarily interrupting the connection to the SCSI bus. Determining means for determining whether reconnection to the SCSI bus is possible, and reconnecting to the SCSI bus based on information held in the holding means when the determination means determines that reconnection to the SCSI bus is possible. 2. The bus control system according to claim 1, wherein the target includes means for performing the operation. 3. The storage means is configured to store, for each of the identification information, a valid time set to be longer than a normal execution time in the bus phase and shorter than a monitoring time of the timer monitoring. The bus control system according to claim 1 or 2, wherein: (4)An initiator and the initiator
Target to be selected, the initiator and the target
A SCSI bus for connecting the
Timer monitors the bus phase with the target
A reset signal is output when the bus phase is tied out.
Bus control system configured to send on SCSI bus
And Corresponding to the identification information for identifying the initiator.
Valid time generated in advance based on the monitoring time of Ima monitoring
Storage means for storing Time between
Timer means to perform, and the time counted by the timer means is valid.
Suspends the connection to the SCSI bus when
Means in the target.  The storage means stores the effective time for each bus phase.
The time keeping means measures time in each bus phase.
A bus control system characterized in that the bus control system is configured to perform the operation. 5. A intended to perform a bus operation by a control command from the host device, the execution time of the bus operations before
A target that varies according to the load of the host device, an initiator that selects the target, and a SCSI bus that connects the initiator and the target, wherein the initiator performs a timer monitoring of a bus phase between the target and the target. A bus control system configured to send a reset signal onto the SCSI bus at the time of tie-out of the bus phase, wherein the bus control system is generated in advance based on a monitoring time of the timer monitoring corresponding to identification information specifying the initiator. Storage means for storing the valid time, a clock means for measuring the execution time of the bus phase, and means for temporarily suspending connection to the SCSI bus when the clock time of the clock means exceeds the valid time. A bus control system provided in the target. 6. A holding means for holding information necessary for reconnection to the SCSI bus when the connection to the SCSI bus is temporarily suspended, and to the SCSI bus after temporarily suspending the connection to the SCSI bus. Determining means for determining whether reconnection to the SCSI bus is possible, and reconnecting to the SCSI bus based on information held in the holding means when the determination means determines that reconnection to the SCSI bus is possible. 6. The bus control system according to claim 5, wherein the target includes means for performing the operation. 7. The timer monitor according to claim 1, wherein the storage means is longer than a normal execution time of each of a bus phase including a message out phase, a message in phase, a command phase, a data phase, and a status phase. 7. The bus control system according to claim 5, wherein the effective time set so as to be shorter than a monitoring time is stored. Claim 8.Bus operation by control command from host device
Target to perform the operation on and select the target
An initiator, and the initiator and the target
And a SCSI bus for connecting the
Timer monitoring the bus phase with the target
A reset signal is output when the bus phase is tied out.
Bus control system configured to send on SCSI bus
And Corresponding to the identification information for identifying the initiator.
Valid time generated in advance based on the monitoring time of Ima monitoring
Storage means for storing the time of the bus phase
Timer means to perform, and the time counted by the timer means is valid.
Suspends the connection to the SCSI bus when
Means in the target.  The storage means stores the effective time for each bus phase.
The time keeping means measures time in each bus phase.
A bus control system characterized in that the bus control system is configured to perform the operation.