JPH1097507A - System and method for lock control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize fast lock control by locally performing lock control for sharing main storage. SOLUTION: The lock control for respective processors 201-204 is performed by lock request controllers in cache units 205 and 206 to which the processors 201 to 204 are connected according to the state of a lock variable. Each lock request controller once receiving a lock request or unlock request looks up in a lock address register which holds the address of the lock variable to refer to the lock state stored in the corresponding lock status register. As the state of the lock variable, not only a table which merely shows that individual devices are in lock or unlock states, but also various states are defined. For example, ULE shows a state wherein it is confirmed that none of the devices secures a lock. Consequently, a lock is speedily obtained without confirming the states of other devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to lock control for a data processing system, and more particularly to a lock control system and method for a data processing system having a plurality of data processing devices sharing a main memory.

[0002]

2. Description of the Related Art In a data processing system, conventionally,
A plurality of data processing devices may be configured to share a main memory. In such a case, it may be necessary for a certain data processing device to exclusively use data in a certain shared area for a certain period. For example, when a certain data processing device performs an operation of adding 1 to data of a certain shared area, during a series of processing of reading data of the shared area, adding 1, and then writing the same again to the shared area,
Access to the data from other data processing devices must be prohibited. Otherwise, the result of updating the data will not be guaranteed.

A lock variable is used to guarantee this exclusive access. When accessing the shared area, it is necessary to check this lock variable to make sure that it is not locked. If the lock variable is in the unlocked state, it is locked and then the corresponding shared area is accessed. Return the lock variable to the unlocked state after exclusive processing is completed. Such control is called lock control.

For example, Japanese Patent Application Laid-Open No. 56-21260 discloses a technical idea of an access device for performing lock control on main memory access from a plurality of processing devices. In this conventional technique, two states, that is, a lock is acquired and a lock is not acquired, are used as the state of the lock variable. Therefore, a request to acquire a lock by a certain storage control device (hereinafter referred to as a request)
When a request to release a lock (hereinafter, referred to as an "unlock request") or a request to release a lock (hereinafter, referred to as an "unlock request"), the state of a lock variable in another storage control device is checked or updated. For example,
If a lock request is issued from a certain data processing device and the lock variable held in the storage controller connected to the data processing device indicates an unlocked state, the state of the lock variable in another storage control device Will have to be searched. If the result of the index indicates that the lock request is locked, the lock request fails, and the data processing device issues the lock request again. Such an operation is called spin lock.

[0005]

In the above-mentioned prior art, when the data processing device issues a new lock request, the lock is acquired if the lock variable indicates an unlocked state in the storage control device. Access to lock variables in other storage controllers will have to be accessed. For this reason, in the related art, there is a problem that the time required for acquiring the lock becomes longer and bus traffic increases due to unnecessary bus access.

Accordingly, it is an object of the present invention to provide an improved lock control system for sharing main memory.

Another object of the present invention is to provide a lock control method for locally and quickly performing a process for lock control.

[0008]

SUMMARY OF THE INVENTION The present invention provides a plurality of locks for controlling the state of a lock variable for at least one of a plurality of data processing devices in a data processing system having a plurality of data processing devices sharing a main memory. In a lock control system having a control device, there is provided a registration unit for registering at least one state of a lock variable, and a state holding unit for holding a state of the lock variable registered in the registration unit, wherein the state holding unit includes The first state indicates that it is unknown whether some of the plurality of lock control devices have acquired the lock and the other lock control devices have acquired the lock. A second state indicating that the lock has not been acquired also in the control device, and a case where some of the lock control devices have acquired the lock and other A third state indicating that the lock control device is in the first state, and indicating that the lock control device transitions to the second state in response to the unlock request; And a fourth state indicating that the state is changed to the second state in response to the unlock request.
The lock control system is characterized in that lock acquisition is performed at high speed.

[0009] Further, when a lock request is issued for a lock variable in the second state, it is preferable to determine success of lock securing without referring to the state of another lock control device.

Further, when a lock request is issued for a lock variable in the third or fourth state, it is more preferable that the lock request is not transmitted to another lock control device.

Furthermore, when an unlock request is issued for a lock variable in the third state, it is more preferable not to transmit the unlock request to another lock control device.

Further, a lock control method for controlling a plurality of lock control devices for controlling a state of a lock variable relating to at least one of the plurality of data processing devices in a data processing system having a plurality of data processing devices sharing a main memory. The state of the lock variable is at least 1
And a state holding procedure for holding the state of the lock variable registered in the registration means, wherein the state holding procedure acquires a lock as a state of the lock variable by a part of the plurality of lock control devices. And a second state indicating that it is unknown whether another lock control device has acquired a lock and a second state indicating that no lock control device has acquired a lock. Indicates that some of the lock control devices have acquired the lock, and that the other lock control devices are in the first state, and that the lock control apparatus transitions to the second state in response to the unlock request. And a fourth state indicating that one of the lock control devices has secured the lock and that the lock control device transitions to the second state in response to the unlock request. Lock change When the lock request is issued, it is determined that the lock securing is successful without referring to the state of the other lock control devices, and the lock request is issued with respect to the lock variables in the third and fourth states. In this case, the lock request is not transmitted to the other lock control device, and when the unlock request is issued for the lock variable in the third state, the unlock request is not transmitted to the other lock control device. Any lock control method may be used.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a data processing system to which the present invention is applied will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a data processing system to which the present invention is applied. This system includes four processing devices 201 sharing the storage device 207.
To 204. Then, the processing devices 201 and 20
2 is connected to the cache unit 205 and the processing device 20
3 and 204 connect to the cache unit 206. The cache units 205 and 206 and the storage device 207 are connected via a system bus 208. Each of the cache units 205 and 206 has a function as a cache memory for the processing devices 201 to 204 to be connected, and also has a function of holding a lock variable. In addition, the system bus 208
An address bus and a data bus are included, and the address bus and the data bus can operate independently. A lock request that requests acquisition of a lock and an unlock request that requests release of a lock use only the address bus. Further, system bus 208 includes a bus for transmitting cache information, and is used to transmit whether or not a lock request can be acquired for a lock request.

FIG. 2 is a block diagram showing the configuration of the cache unit of the present invention. The cache unit 205 or 206 includes a request buffer 21 and a request buffer 22 for holding a request from the processing device, and a system bus 20.
Request or request buffer 2 issued to 8
A selector 23 for selecting 1 or 22; an address array 24 of the cache memory; a lock request controller 25; and selectors 26 and 27 for selecting a request selected by the selector 23 or a lock determination result from the lock request controller 25. And

The request buffers 21 and 22 hold a plurality of requests and each function as a first-in first-out buffer. The selector 23 selects one of the three inputs according to a predetermined rule. For example, a round robin method in which each input is sequentially selected can be used. Further, a method in which a request from the system bus is treated as the highest priority can be used. The address array 24 has the same configuration as a normal cache memory (not shown), and stores a tag address corresponding to each entry of the data memory.

The selectors 26 and 27 select the output of the lock request controller 25 when returning a reply to the lock request, and select the output of the selector 23 when performing cache memory match control.

FIG. 3 is a block diagram showing the configuration of the lock request control device of the present invention. The lock request control device 25 stores the lock address registers 1 and 2 for storing the addresses of the lock variables for the request selected by the selector 23, and the lock state for each lock variable stored in the lock address registers 1 and 2. Lock status registers 5 and 6
Lock address match detection circuits 3 and 4 for inputting the address of the lock variable from selector 23 and the addresses held in lock address registers 1 and 2 to detect a match therebetween, and a lock address match detection circuit A selector 7 for selecting the contents of the lock status register 5 or 6 for the entry for which a match is detected in 3 or 4
And a lock request control circuit 8 for controlling the states of the lock address registers 1 and 2 and the lock status registers 5 and 6.

Next, an embodiment of the present invention in the data processing apparatus will be described with reference to the drawings.

FIG. 4 is a diagram showing the state of the lock variable in the embodiment of the present invention. The lock variable in the present embodiment takes one of four states, ULE, ULS, LKE, and LKS. LKE indicates a state in which the data processing device connected to the cache unit has secured the lock, and the other data processing devices have not secured the lock. LKS means that a lock has been acquired in any of the cache units in the system. The cache unit acquiring the lock may be itself or another cache unit. The ULS indicates a state in which the data processing device connected to the cache unit has not secured the lock, and it is unknown whether another data processing device has secured the lock. ULE indicates a state in which it has been confirmed that the lock is not secured by the data processing device connected to any of the cache units. If the state of the lock variable is ULE, the state of the lock variable of another cache unit is not checked again,
It becomes possible to acquire a lock.

FIG. 5 is a diagram showing an operation when a lock request occurs in the embodiment of the present invention. From this figure,
The operation in this embodiment when a lock request is issued from the data processing device will be described. The leftmost column shows the state of the lock variable in the cache unit connected to the data processing device that issued the lock request, and the middle column shows the state of the lock variable in the other cache units. The rightmost column shows the operation in each case. Hereinafter, a cache unit connected to the data processing device that has issued the request is referred to as a local cache unit.

For example, if the state of the lock variable of the local cache unit is LKS or LKE, the lock has already been secured, and the lock control device returns a "lock failed" result. If the state of the local cache unit is ULE, it is known that no data processing device has secured the lock. Therefore, the lock control device returns a result of “lock succeeded” and changes the state of the lock variable. LKE.

When the state of the lock variable of the local cache unit is ULS, it is necessary to refer to the state of the lock variable of a cache unit other than the local cache unit. That is, if the state of the lock variable of the cache unit other than the local cache unit is LKS or LKE, the lock control device returns a result of “lock failure”. If the state is U
If it is LE, the lock control device returns a result of “lock succeeded”, and sets the state of the lock variable of the local cache unit to LKE and the state of the lock variable of the other cache units to ULS. If the status of the lock variable of the cache unit other than the local cache unit is ULS or the lock variable is not registered in the lock address register, the lock control device returns the result of “lock succeeded” and the local LKE status of lock variable of cache unit
To

When the lock variable corresponding to the local cache unit is not registered, the same processing as when the lock variable of the local cache unit is ULS is performed. However, in this case, the address of the lock variable related to the lock address is registered in the lock address register. At this time, if the lock can be secured, the state of the lock variable is set to LKE. If the lock variable cannot be secured, the state of the lock variable is set to ULS.

FIG. 6 is a diagram showing an operation when an unlock request occurs in the embodiment of the present invention. With reference to this figure, an operation in the present embodiment when an unlock request is issued from the data processing device will be described. The left column shows the state of the lock variable in the cache unit connected to the data processing device that issued the lock request, and the right column shows the operation in each case. That is, if the state of the lock variable of the local cache unit is LKE, the lock request control device changes the state of the lock variable to ULE. Further, when a lock has not been acquired, an unlock request cannot normally occur, so that the state of the lock variable of the local cache unit cannot be ULE or ULS. In addition, even when the corresponding lock variable is not registered, an unlock request cannot normally occur.

FIG. 7 is a diagram showing a specific example of the operation in the embodiment of the present invention. The features of the present embodiment will be described with reference to FIG. (A) is an initial state, (B) is a state after issuing an unlock request, (C) is a state after acquiring a lock, (D) is a state when lock securing fails, and (E) is a state after releasing a lock request. Is shown.

First, as shown in (A), the state of the lock variable of the left cache unit 205 is ULS, and the state of the lock variable of the right cache unit 206 is LKE.
When an unlock request is issued by the right cache unit 206, as shown in FIG.
The state of the lock variable of the right cache unit 206 is updated from LKE to ULE (see FIG. 6). In this state, when the lock request is issued again by the right cache unit 206, the lock can be acquired by the right cache unit 206 regardless of the state of the other cache units 205 as shown in FIG. That is,
The state of the lock variable of the right cache unit 206 is updated to LCK (see FIG. 5). When a lock request is issued in the left cache unit 205 in this state, lock securing fails, and the state of the lock variable of the left cache unit 205 is updated from ULS to LKS and the right cache The state of the lock variable of the unit 206 is updated from LKE to LKS (see FIG. 5). As a result, the left cache unit 20
No. 5 does not issue a lock request to the outside. This state is released by the right cache unit 206.
Is when the unlock request is issued. That is, in this case, as shown in (E), the state of the lock variable of the left cache unit 205 becomes ULS (see FIG. 6), so that the lock request can be issued to the outside again.

As described above, according to the embodiment of the present invention, by providing the lock variable state ULE, it is possible to obtain the lock after releasing the lock at high speed, and to provide the lock variable state LK8. As a result, it is possible to suppress unnecessary issuance of a lock request after lock failure. Furthermore, by providing the lock variable state LKE,
There is an effect that it is not necessary to operate another cache unit to release the lock from the LKE state.

[0029]

As described above, according to the present invention, by providing the status of various lock variables in correspondence with the lock address register, the status of the second cache which is not directly connected to the central processing unit which has issued the lock request is provided. Eliminates the need to reference a lock variable. This has the effect of increasing the speed of lock acquisition and eliminating unnecessary bus access to reduce the increase in bus traffic.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a data processing system to which the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of a cache unit according to the present invention.

FIG. 3 is a block diagram showing a configuration of a lock request control device of the present invention.

FIG. 4 is a diagram illustrating a state of a lock variable according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating an operation when a lock request occurs in the embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation when an unlock request occurs in the embodiment of the present invention.

FIG. 7 is a diagram showing a specific example of an operation in the embodiment of the present invention. (A) is an initial state, (B) is a state after issuing an unlock request, (C) is a state after acquiring a lock,
(D) shows the state at the time of lock failure, and (E) shows the state after the lock request is released.

[Explanation of symbols]

 1, 2 Lock Address Register 3, 4 Lock Address Match Detection Circuit 5, 6 Lock Status Register 7 Selector 8 Lock Request Control Circuit 21, 22 Request Buffer 23 Selector 24 Address Array 25 Lock Request Control Device 26, 27 Selector 28, 29 Buffers 201 to 204 Processing device 205, 206 Cache unit 207 Storage device 208 System bus

Claims (5)

[Claims] 1. A data processing system having a plurality of data processing devices sharing a main memory, wherein the plurality of lock control devices respectively control a state of a lock variable relating to at least one of the plurality of data processing devices. A lock control system, comprising: a registration unit that registers at least one state of the lock variable; and a state holding unit that holds a state of the lock variable registered in the registration unit. A first state indicating that some of the plurality of lock control devices have not acquired a lock and it is unknown whether another lock control device has acquired a lock, as the state of the variable; A second state indicating that lock has not been acquired also in the lock control device of the above, and a part of the plurality of lock control devices has acquired a lock. And a third state indicating that another lock control device is in the first state, and indicating that the lock control device makes a transition to the second state in response to an unlock request. A lock control system that secures a lock, and has a fourth state that indicates a transition to the second state in response to an unlock request, so that lock acquisition is performed at high speed. . 2. When a lock request is issued for a lock variable in the second state, it is determined that lock securing has succeeded without referring to the state of another lock control device. The lock control system according to claim 1. 3. The lock control device according to claim 1, wherein when a lock request is issued for the lock variables in the third and fourth states, the lock request is not transmitted to another lock control device. A lock control system as described. 4. The lock control device according to claim 1, wherein when an unlock request is issued for the lock variable in the third state, the unlock request is not transmitted to another lock control device. The lock control system according to any one of the above. 5. In a data processing system having a plurality of data processing devices sharing a main memory, a plurality of lock control devices for controlling states of lock variables relating to at least one of the plurality of data processing devices are controlled. A lock control method, comprising: a registration step of registering at least one state of the lock variable; and a state holding step of holding the state of the lock variable registered in the registration unit. A first state indicating that some of the plurality of lock control devices have not acquired a lock and it is unknown whether another lock control device has acquired a lock, as the state of the variable; A second state indicating that lock has not been acquired also in the lock control device of the above, and a part of the plurality of lock control devices has acquired a lock. And a third state indicating that another lock control device is in the first state, and indicating that the lock control device makes a transition to the second state in response to an unlock request. A lock request is issued for a lock variable in the second state, and a fourth state indicating that the lock state is transited to the second state in response to the unlock request. If the lock request is issued for the lock variables in the third and fourth states, it is determined that the lock securing is successful without referring to the state of the other lock control device. If the lock request is not transmitted to the lock controller and an unlock request is issued for the lock variable in the third state, the unlock request is sent to another lock controller. Lock control method, characterized in that it does not convey.