JP3214461B2 - Bus control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bus control device.

[0002]

2. Description of the Related Art Conventionally, in a server system used for a database or the like, a number of peripheral devices such as a disk device (hereinafter referred to as a target) are provided in a server computer (hereinafter referred to as a server computer) in proportion to the amount of data held. Connected to store and manage data. SC is used to connect the server to multiple targets.
SI (Small Computer System Interface) connection is generally used.

As shown in FIG. 1, in a conventional server system, a server 21 and a plurality of disk devices 22 to 2 are provided.
4 are connected to each other via a bus 2. Each of the server 21 and the targets 22 to 24 includes the bus control device 1. Referring to FIG. 6, a conventional bus control device 11 includes an input / output unit 17 for managing data transfer between the bus 2 and a target including the device 11, and a processing unit for performing various processes associated with bus arbitration. 16 are provided.

In such a conventional device, the bus 2
A certain participation time is provided for the arbitration of the request, and the request having the highest priority among the requests which participated in that time has acquired the right to use the bus 2.

In such a conventional apparatus, when the connection between the bus 2 and a number of targets is a SCSI connection, each target is given an ID according to the SCSI rules.
Numbers were assigned, and the use priority of the bus 2 was set to each target in the order of the numbers. Such a method of assigning priorities generally has no problem when the load on the bus 2 is light, but when the load on the bus 2 becomes heavy,
There is a possibility that a target having a low priority cannot acquire the right to use the bus 2 at all.

For example, in FIG. 1, it is assumed that a read request is issued from the server 21 to the disk device 22 via the bus 2. Normally, when the disk device 22 receives a read request, it does not need to obtain new information from the server 21 after receiving the read start address and the transfer data length from the server 21. It simply waits without doing anything until the read process in the disk device 22 is completed and the data is transferred. Therefore, in order to increase the usage rate of the bus 2, the connection between the server 21 and the disk device 22 is temporarily disconnected, the bus 2 is temporarily released, and the reconnection is performed after the read processing in the disk device 22 is completed. It is common to request.

At the time of this reconnection, the processing unit 16 of the bus control device 11 in FIG. 6 in the disk device 22 tries to acquire the right to use the bus 2, but if the priority of the disk device 22 is low, the bus 2 right to use may not be obtained immediately. If the disk device 22 does not obtain the right to use the bus for a certain period of time, the server 21 determines that the reading process has not been completed normally if there is no response to the reading request for a certain period of time. With such a configuration, processing such as making a read request again is performed. In particular, when the server 21 is used for a database or the like, an additional process of returning all the series of processes related to the read process that did not end normally to the status before the execution is performed, and extra system is required. Processing time and load occur.

[0008]

In the above-mentioned prior art,
If the reselection process requesting reselection (hereinafter referred to as reselection) occurs in a state in which the right to use the bus 2 cannot be acquired for a certain period of time or more, it is determined that the reselection process is not completed normally and the process is executed. Since the process of returning to the previous state is performed, the performance of the entire system is deteriorated. For this reason, in a conventional system in which a heavy load is applied to a bus, only a half of the number of disk devices or the like can be connected to the SCSI standard.

An object of the present invention is to solve such a problem and to construct a high-performance system in which an abnormality such as a timeout does not occur even in a system in which a heavy load is applied to a bus.

[0010]

In order to solve the above-mentioned problems, a bus control device according to the present invention is a bus control device provided for each of a plurality of targets connected to each other via a bus. It has means for delaying or prohibiting the target from participating in bus arbitration depending on the state.

A monitoring unit for monitoring a processing request propagating on the bus; and determining whether the processing request propagating on the bus is a processing request that requires reselection of the bus. If there is a processing request that requires reselection, an identification unit that outputs information of the processing request, a storage unit that stores the information of the processing request according to an instruction from the identification unit, and a process that is stored in the storage unit. A processing unit for delaying or prohibiting the target from participating in arbitration based on the information content of the request.

[0012] The monitoring unit may extract control-related information attached to a processing request exchanged with another target propagating on the bus and send the control-related information to the identification unit. On the basis of the control-related information, it is determined whether or not the processing request is a processing request that requires reselection of a bus.

Further, the information of the processing request requiring the reselection of the bus stored in the storage unit includes the time at which the instruction for the processing request is issued and the identification of the target of the request destination of the processing request. And a number.

Further, the processing unit determines whether or not the current time has passed a predetermined set time or more from the time at which the processing request stored in the storage unit was issued. When there is a processing request that has passed the set time or more, the target is characterized by delaying its own participation in arbitration.

Further, the processing unit monitors a bus request propagating on the bus, and when detecting a bus request having an identification number of the processing request that has passed the set time or more, the processing unit determines that the target participates in arbitration. It is characterized by prohibition.

Further, when the processing unit detects a bus request having an identification number of a processing request that has passed the set time or more, the processing unit instructs to delete information of the processing request stored in the storage unit. And

Further, the processing unit does not delay participation in arbitration when a processing request having the identification number of its own target is included in the processing requests that have passed the set time or more.

A bus control method according to the present invention is a bus control method for controlling connection of a plurality of targets connected to each other via a bus to the bus, wherein the processing request propagates on the bus. Monitoring and determining whether the processing request is a processing request that requires reselection of the bus, and if the processing request is a processing request that requires reselection of the bus, information on the processing request Is output to a storage unit, and based on the information content of the processing request stored in the storage unit, a timeout for delaying or prohibiting the target from participating in arbitration is monitored.

[0019] The monitoring of the timeout may include determining whether a current time has passed a predetermined time or more from a time at which the processing request stored in the storage means was issued, If there is a processing request that has passed the set time or more and the processing request to the target itself is not included in the processing request, the participation of the target in the arbitration is delayed, and the processing request that has passed the setting time or more is Upon receiving the notification that the reselection processing has occurred, the target is prohibited from participating in the arbitration.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Referring to FIG. 1, an embodiment of the present invention comprises a server 21 and a disk device 22 as a target.
, 23 and other peripheral devices 24, etc., and a bus 2 connecting the server 21 and the devices 22 to 24. Each of the server 21 and the devices 22 to 24 includes the control device 1. Referring to FIG. 2, the bus control device 1 of the present invention includes a monitoring unit 3, an identification unit 4, a storage unit 5,
It comprises a processing unit 6 and an input / output unit 7. The input / output unit 7 and the monitoring unit 3 are connected to the bus 2.

In the bus control device 1, the monitoring unit 3
Sends various processing requests of each target propagating on the bus 2 to the identification unit 4. In this embodiment, the bus 2 is assumed to be SCSI.

The identification unit 4 determines whether the processing request received from the monitoring unit 3 is a processing request that requires reselection such as a read process. If the processing request requires reselection, the request issue time at which the processing request was issued and the ID number of the target that is the target of the processing request are extracted.

Here, the processing request that requires reselection means that the requested processing cannot be completed by only one processing.
This is a type of processing request in which processing is completed by performing reselection processing such as data transfer again after a certain period of time.

When the identification unit 4 determines that the request requires reselection, the storage unit stores the instruction issue time at which the processing request was issued and the target ID number of the target to which the processing request is applied. 5 is sent.

The storage unit 5 is a memory for temporarily storing the instruction issue time and the target ID number sent from the identification unit 4.

The processing unit 6 compares the request issue time of the processing request stored in the storage unit 5 with the current time before the arbitration participation time, and elapses a preset time (hereinafter referred to as a timeout). )), The reselection processing for the processing request is not performed, that is, when it is detected that the bus request by the reselection processing is not generated from the target,
The target ID number of the processing request is extracted. Then, it is determined whether or not the timeout target ID number includes the own target ID number. If the target ID number of the own target exists, no processing is performed and the process waits until the start of arbitration. On the other hand, if the target ID number of the own target is not included, an instruction is issued to the input / output unit 7 to delay participation of the own target in arbitration.

When an instruction to delay participation in arbitration is sent from the processing unit 6, the input / output unit 7 sets the timing to participate in arbitration generated from the arbiter of the target (not shown) immediately before the end of the arbitration allowable time. Delay until.

When participation in arbitration is started, the processing unit 6 monitors a bus request propagating on the bus 2 via the input / output device 7. When it is detected that a bus request has been issued from the target having the target ID number in which the timeout has occurred, the input / output unit 7 is prohibited from participating in the arbitration of the target itself. At the same time, it instructs the storage unit 5 to delete the target ID number and the request issue time of the processing request stored therein. When the input / output unit 7 receives the participation prohibition signal from the processing unit 6, the input / output unit 7 cancels the participation in the current arbitration.
As a result, the target of the target ID number that has timed out acquires the right to use the bus, and the reselection processing for the processing request that has timed out is performed.

On the other hand, if the reselection processing for the target ID number that has timed out while the target is delaying participation in arbitration does not participate in arbitration, the input / output unit of the target that has delayed participation in arbitration 7 participates in arbitration after waiting until just before the end of the allowable time for participation in arbitration. As a result, arbitration based on the normal priority is performed, and the target with the highest priority acquires the right to use the bus 2.

As described above, the input / output unit 7 has a function of delaying or prohibiting the timing at which the target itself participates in arbitration in accordance with an instruction from the processing unit 6.

Next, a more detailed operation of this embodiment will be described with reference to the flowcharts of FIGS.

The monitoring unit 3 in the bus control device 1 of each of the targets 22 to 24 constantly monitors the bus 2 (Step 1 in FIG. 3). When a processing request is issued from the server on the bus 2, the monitoring unit 3 sends a copy of the entire processing instruction (or only a necessary part) to the identification unit 4 (step 2). The identification unit 4 determines whether this processing request is a processing request that requires reselection processing (step 3). If the processing request requires reselection processing, the processing request is issued to the storage unit 5. The request issue time and the target ID number of the target to be processed are stored (step 4).

Next, the timeout monitoring operation of the processing section 6 will be described in detail.

The processing unit 6 starts monitoring the timeout before the arbitration participation time (step 10 in FIG. 4). First, the processing unit 6 compares the request issue time of the processing request stored in the storage unit 5 with the current time, and determines whether a preset time has elapsed (step 11).
If there is a processing request for which the set time has elapsed, the target ID number of the processing request is extracted, and it is determined whether or not the target request ID number is included (step 1).
2). If the ID number of the target itself is included, the process waits until the start of arbitration (step 14).
On the other hand, if the target ID number of the processing request that has timed out does not include the ID number of the target itself, an instruction is issued to the input / output unit 7 to delay participation of the target in arbitration (step 13). When the arbitration participation time starts, the processing unit 6 monitors whether or not a bus request has been issued from the target of the timed-out target ID number via the input / output unit 7 until immediately before the end of the arbitration participation time (step). 14). When it is detected that a bus request has been issued from the target of the target ID number that has timed out, it is determined that reselection processing for the stored processing request has occurred, and the input / output unit 7 is notified of the arbitration of its own target. An instruction is issued to prohibit participation (step 15). Thus, when the participation time of the arbitration ends, the target that has issued the bus request can acquire the bus 2 and the reselection process is executed. On the other hand, if the processing unit 6 does not detect that a bus request has been issued from the target having the timed-out target ID number while delaying participation in arbitration,
The input / output unit 6 participates in arbitration. As a result, arbitration based on normal priorities is performed, and the target with the highest priority acquires the right to use the bus 2.

Next, this embodiment will be described in detail with reference to the timing chart of FIG. First, FIG.
In (a), the busy signal BSY * is "H (high)".
Indicates that the bus 2 is free. Then, when the bus 2 is in a free state (time t0), after a certain period of time, the (t1) BSY * signal becomes "L (low)" and participation in arbitration is started. Each device is B
Until the SY signal * becomes “L”, the timeout of the processing request stored in the storage unit 5 is monitored. BSY signal *
Becomes “L” and starts participating in arbitration until a certain time has elapsed (time t2)
Participate in arbitration as needed.

Here, as an example, the apparatus a, the apparatus b, and the apparatus c
Is assumed. According to the SCSI regulations, the priority order assigned to each device is referred to as device a, device b, and device c in descending order. In each of the bus requests a, b, and c in FIG. 5, the state of “H” indicates participation in arbitration. The command a, the command b, and the command c are transmitted from the processing unit 6 to the input / output unit 7 in each device.
Represents instructions issued to

First, referring to FIG. 5A, it is assumed that the device a has participated in the arbitration when there is no processing request that has timed out. Here, if another device b or device c also wants to participate in the arbitration, it can participate in the arbitration by announcing the participation between the times t1 and t2. Then, the arbitration participation time ends (time t
2) Then, the device with the highest priority among the participating devices acquires the priority. Therefore, in this case, the device a acquires the right to use the bus 2.

Next, referring to FIG. 5B, when a timeout occurs due to the processing request of the target ID number of the device c, the timeout is detected in the processing unit 6 of each device other than the device c, and the input / output is performed. An instruction is given to the unit 7 to delay its participation in arbitration (time t1). When the device c participates in the arbitration while each device delays the participation in the arbitration (time t3), the processing unit 6 of each device detects this and notifies the input / output unit 7 to participate in the arbitration of the own device. Is prohibited (time t4). As a result, the device c can acquire the right to use the bus 2 at the time t2, and the reselection process of the device c having the lower priority is performed. On the other hand, when the device c does not participate in the arbitration while each device delays the participation in the arbitration (FIG. 5C), the device a which has been delayed
Then, the device b waits until immediately before the end of the arbitration participation allowable time, and then participates in the arbitration, and normal arbitration is performed.

The bus control device 1 of the present invention can be used on the same bus 2 by mixing with the conventional bus control device 1. In this case, the bus control device 1 of the present invention
Operate in accordance with the priority order between devices that are not connected, but the conventional problem occurs. However, the device using the bus control device 1 according to the present invention operates in a direction to alleviate this, so that it is partially operated. Even if there is, the effect can be obtained.

As described above, according to the embodiment of the present invention, when the bus control device 1 detects that there is a processing request requiring reselection after a predetermined time has elapsed in another target. , Delay your target's participation in arbitration. Further, when the reselection processing for the processing request participates in the arbitration, by prohibiting the target from participating in the arbitration, an abnormality such as a timeout can be prevented, and in a system having a high load on the bus 2, It is possible to connect more targets than before and operate normally.

[0042]

As apparent from the above description, according to the present invention, in a server system having a high load on a bus,
Even if a large number of targets are connected to the bus, a high-performance system can be constructed in which no abnormality such as timeout occurs.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a bus control device 1 of the present invention.

FIG. 3 is a flowchart showing the operation of the present invention.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a timing chart of the embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a conventional bus control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bus control device 2 Bus 3 Monitoring part 4 Identification part 5 Storage part 6 Processing part 7 Input / output part 16 Processing part 17 Input / output part 21 Server 22, 23 Disk device

Claims (7)

(57) [Claims] 1. A bus control device provided in each of a plurality of targets mutually connected via a bus, wherein a bus use right is acquired even after a predetermined time has elapsed.
If there are other targets that can not be, arbitration participants to participate in the bus arbitration of its own target
Delay until a first point in time, and after the first point in time
To bus arbitration from the other target
Bus arbitration of own target when there is participation
Participation in the other target and the other target after the first time point.
When there is no participation in bus arbitration
Means that the target participates in bus arbitration.
A bus control device having means for performing the arbitration during the participation period . 2. A monitoring unit for monitoring a processing request propagating on the bus, and determining whether the processing request propagating on the bus is a processing request that requires reselection of the bus. An identification unit that outputs information of the processing request if there is a processing request that needs to be reselected; a storage unit that stores the information of the processing request according to an instruction from the identification unit; and a process that is stored in the storage unit. Based on the information content of the request,
Bus usage right is acquired even after a predetermined time has passed
If there are other targets that can not be, arbitration participants to participate in the bus arbitration of its own target
Delay until a first point in time, and after the first point in time
To bus arbitration from the other target
Bus arbitration of own target when there is participation
Participation in the other target and the other target after the first time point.
When there is no participation in bus arbitration
Means that the target participates in bus arbitration.
2. The bus control device according to claim 1, further comprising a processing unit that performs processing during the arbitration participation period . 3. The monitoring unit extracts control-related information attached to a processing request being exchanged by another target propagating on the bus and sends the control-related information to the identification unit. 3. The bus control device according to claim 2, wherein it is determined based on the control-related information whether the processing request is a processing request that requires a bus reselection. 4. The information of a processing request that requires reselection of a bus stored in the storage unit includes a time at which an instruction for the processing request is issued and an identification of a target of a request destination of the processing request. A number is included.
A bus control device as described. Wherein said processing unit, of its own target Basua
3. The bus control device according to claim 2 , wherein when participation in the bite is prohibited, an instruction to delete the information of the processing request stored in the storage unit is issued. Wherein said processing unit, when processing requests passed over the plant constant time is of the own target is sent, the bus of claim 1, wherein the not delayed participation in arbitration Control device. 7. A bus control method for controlling connection of a plurality of targets connected to each other via a bus to the bus, wherein a processing request propagating on the bus is monitored, and the processing request is It is determined whether or not the processing request requires reselection of a bus. Based on the information content of the processing request stored in the storage means, the bus use right
Abitoreshi but if there are other targets that can not be acquired, to participate in the bus arbitration of its own target
Delay until the first point in time during the
Bus arbitration from the other target
Bus arbitration for your target
Prohibition of participation in the other
No participation in bus arbitration from the target
To participate in your own target's bus arbitration
A bus control method for monitoring a time-out in which the addition is performed during the arbitration participation period .