JP2518134B2 - Shared resource exclusive control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shared resource exclusive control system, and more particularly to a shared resource exclusive control system for a computer system.

[0002]

2. Description of the Related Art A resource used by a plurality of tasks in a computer system requires exclusive control in order to serialize access to the resource. For such exclusive control, the computer system is provided with a basic function called lock / unlock (or ENQ / DEQ), and there are two types of lock requests, a normal exclusive mode and a shared mode. .

The basic operation of exclusive control is as follows. When a task issues a lock request, if the lock request target resource is not locked by another task, or if the lock mode of the resource and the lock request mode of the task are both in shared mode, immediately Lock right is granted. However, when the lock mode of the resource or the lock request mode of the task is the exclusive mode, the lock is waited.

When the task that has locked the resource issues an unlock request, the exercise of the lock right of the task ends. If there is no other locked task and there is a lock waiting task, and the request mode of the task that made the lock request earliest among them is the exclusive mode, the lock right is given only to that task, and if it is the shared mode. For example, it grants the lock right to all tasks currently waiting for the lock in shared mode.

As a prior art document, for example, Japanese Unexamined Patent Publication No. Hei.
There are Japanese Patent Laid-Open No. 118843 and Japanese Patent Laid-Open No. 3-83142.

[0006]

In the above-mentioned conventional shared resource exclusive control method, when a plurality of resources are simultaneously used and processed, a lock request is issued to each resource, but some resources are successfully locked. However, if a lock wait occurs while trying to lock the next resource, the waiting time of other tasks waiting for the lock of the already locked resource becomes unnecessarily long, and the resource usage efficiency decreases. There is.

In view of the above points, an object of the present invention is to provide a shared resource exclusive control system which reduces the lock waiting time of the subsequent lock waiting task and improves the use efficiency of the shared resource. .

[0008]

According to the shared resource exclusive control method of the present invention, in the shared resource exclusive control method of a computer system, a weight is set in advance for each resource, and the lock waiting of the locked resources of the task is waited for. The function f (x) of the sum x of the weights of the resources in which the task is present (if a> b, f (a) ≧ f (b) is satisfied, and f (c)> f (d)
A value calculated by a function satisfying c> d and c satisfying c> d) that satisfies the above condition, and a lock priority setting unit that sets a value as a lock priority of the task, and a lock right is assigned to the lock waiting task. Lock order changing means for rearranging the lock queues so that the lock queues are arranged in descending order.

[0009]

The present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a shared resource exclusive control system according to an embodiment of the present invention. The shared resource exclusive control function 7 for realizing the shared resource exclusive control method of the present embodiment is a lock request processing means 1 for processing a lock request.
An unlock request processing means 2 for processing an unlock request, a lock order changing means 3 for rearranging the lock queues in order of high lock priority, and a task waiting for a lock among the locked resources of the task. Is composed of a lock priority setting means 4 for setting a value calculated by a function of the sum of weights of existing resources as the lock priority of the task, an exclusive control table 5, and a lock priority table 6. . In FIG. 1, symbols T1 to Tn (n is a positive integer)
Indicates a shared resource use task (hereinafter, simply called a task).

As shown in FIG. 2, the exclusive control table 5 uses a resource name, which is a name for uniquely identifying the exclusive control target resource in the computer system, as a key. The entry for each resource consists of a resource name part, a weight part, a lock mode part, a locked task list, and a lock queue. The weight section records the weight of the resource. The lock mode section records the lock mode when the resource is locked. The locked task list records task identifiers of tasks that lock the resource. The lock queue is a queue of lock requests in a lock wait state, and records a set of task identifiers and lock modes of tasks issuing these lock requests.

As shown in FIG. 2, the lock priority table 6 uses a task identifier, which is a name for uniquely identifying a task in the computer system, as a key. The entry for each task consists of a task identifier part, a lock wait resource name part, a weight summation part, and a lock priority part. The lock waiting resource name section records the resource name of the resource waiting for the lock of the task. The weight summation unit records the sum of the weights of the resources in which the task waiting for the lock exists among the resources locked by the task. The lock priority section records the lock priority of the task.

The lock request processing means 1 performs the following lock request processing (1) or (2).

(1) The lock mode part of the entry of the exclusive control table 5 corresponding to the target resource of the lock request (hereinafter, unless otherwise specified, the weight part, the lock mode part,
When calling the locked task list and the lock queue, consider the entry in the exclusive control table 5 corresponding to the target resource of the lock request or unlock request), or if the lock mode part and the lock mode of the lock request If both are in the shared mode, the lock request processing means 1 records the lock mode of the lock request in the lock mode section, and adds the task identifier of the task issuing the lock request to the locked task list. Next, if the lock queue is not empty, the lock request processing means 1 uses the resource name of the target resource of the lock request, the task identifier of the task that issued the lock request, and the effect of the priority increase request as parameters. The lock priority setting means 4 is called. Finally,
The lock request processing means 1 suspends the processing of the task that issued the lock request.

(2) When the lock mode unit is not empty and the lock mode of the lock request is the exclusive mode, or when the lock mode unit is the exclusive mode, the lock request processing means 1 issues the lock request. A pair of a task identifier and a lock mode of a task is added to the end of the lock queue, and the lock wait resource name part of the lock priority table 6 corresponding to the task identifier of the task (hereinafter simply referred to as lock wait unless otherwise noted). When calling the resource name part, the total weight part, and the lock priority part, consider the entry of the lock priority table 6 corresponding to the task), record the resource name of the target resource of the lock request, and use the resource name as a parameter. Then, the lock order changing means 3 is called. Next, if the number of requests recorded in the lock queue is 1, the lock request processing means 1 gives, for each task recorded in the locked task list, the task identifier of the task and the lock request. When the lock priority setting means 4 is called with the resource name of the target resource and the request for the priority increase request as parameters, and the lock waiting resource name part of the entry of the lock priority table 6 corresponding to the task is not empty, The lock order changing means 3 is called with the resource name in the lock waiting resource name section as a parameter. Finally, the lock request processing means 1 suspends the processing of the task that issued the lock request.

The unlock request processing means 2 processes the unlock request, deletes the task identifier of the task that issued the unlock request from the locked task list, and if the lock queue is not empty, unlocks the task. The lock priority setting means 4 is called with the task identifier of the task that issued the lock request, the resource name of the target resource of the unlock request, and the effect of the priority reduction request as parameters. Next, the unlock request processing means 2 erases the lock mode part when the locked task list is empty. Further, if there is a lock waiting task, the unlock request processing means 2
When the next lock waiting task requests a lock in the exclusive mode, the exclusive mode is recorded in the lock mode part, the task identifier of the task is recorded in the locked task list, and the lock request of the task is issued from the lock queue. If the task is deleted and the next lock-waiting task makes a lock request in shared mode, the shared mode is recorded in the lock mode section, and the task identifiers of all tasks that issue a lock request in shared mode in the lock queue. To the locked task list and delete all shared mode lock requests in the lock queue.

Subsequently, the unlock request processing means 2 records empty in the lock waiting resource name portion of the corresponding entry of the lock priority table 6 for all the task identifiers recorded in the locked task list in the above or. .
Next, if the lock queue is not empty, the unlock request processing means 2 increases the priority of each task identifier, the resource name of the target resource of the unlock request, and the priority of all the task identifiers recorded in the locked task list. The lock priority setting means 4 is repeatedly called as many times as the number of tasks using the request and parameter as parameters. Then, the unlock request processing means 2 restarts the processing of these tasks.

The lock order changing means 3 refers to the lock queue of the exclusive control table 5 corresponding to the resource name specified by the parameter, and refers to the lock priority section of the lock priority table 6 for the lock queue of the entry. , The tasks that issued each lock request are rearranged in order from the highest lock priority. At this time, the lock requests of the tasks having the same lock priority are arranged on a first-come-first-served basis.

If the request designated by the parameter is a priority increase request, the lock priority setting means 4 designates the weight part of the entry of the exclusive control table 5 corresponding to the resource name designated by the parameter by the parameter. It is added to the weight summation part of the entry of the lock priority table 6 corresponding to the task identifier, and if the priority reduction request is made, the weight part of the entry of the exclusive control table 5 corresponding to the resource name designated by the parameter is designated by the parameter. It is subtracted from the total weight part of the entries of the lock priority table 6 corresponding to the assigned task identifier. Next, the lock priority setting means 4 calculates the lock priority with respect to the entry of the lock priority table 6 corresponding to the task identifier designated by the parameter, by referring to the weight summing unit, and calculates this value of the entry. Record in the lock priority section. The lock priority is calculated by c> d, which satisfies the function f (x) of the sum of weights x (f (a) ≧ f (b) if a> b and satisfies f (c)> f (d)). Function for which c and d exist.

FIG. 3 is a timing chart showing a situation in which the four tasks T1 to T4 sequentially issue a lock request and an unlock request to the two resources R1 and R2.

FIGS. 4A to 4D show the states of the exclusive control table 5 and the lock priority table 6 at the respective timings ta to td in FIG. It is assumed that the resource weights are set to 2 for R1 and 1 for R2 in advance, and that resources R1 and R2 are not locked before time t. Further, as the function f (x), f
A function such that (0) <f (1) <f (2) <f (3) is satisfied is used, and the lock waiting resource name portion, the weight summation portion, and the lock priority portion of the lock priority table 6 are respectively It shall be initialized to empty, 0 and f (0).

Next, the operation of the shared resource exclusive control system of the present embodiment thus configured will be specifically described with reference to FIGS. 3 and 4.

When the task T1 makes a lock request for the resource R1 in the exclusive mode at time t, the lock request processing means 1 is called. Since the resource R1 is not locked, the lock request processing unit 1 grants the task T1 a lock right, records the exclusive mode in the lock mode section, and records the task identifier T1 in the locked task list. Next, since the lock queue is empty, the lock request processing means 1 completes the processing of the lock request without calling the lock priority setting means 4.

When the task T2 makes a lock request for the resource R1 in the exclusive mode at time t + 1, the lock request processing means 1 is called. Since the resource R1 is already locked in the exclusive mode, the lock request processing means 1 sets the task T2 in the lock wait state and records the set of the task identifier T2 and the exclusive mode in the lock queue. Next, the lock request processing means 1 records the resource name R1 in the lock waiting resource name portion corresponding to the task identifier T2, and calls the lock order changing means 3 with the resource name R1 of the resource as a parameter. The lock order changing means 3 rearranges the lock queue,
Since there is only one task waiting for lock, the result does not change. Subsequently, since the number of lock requests in the lock queue is 1, the lock request processing means 1 indicates the task identifier T1 of the locked task list, the resource name R1 of the target resource of the lock request, and the priority increase request. Is used as a parameter to call the lock priority setting means 4. The lock priority setting means 4 uses the exclusive control table 5 corresponding to the resource name R1 in the sum of weights of the entries of the lock priority table 6 corresponding to the task T1.
The value 2 of the weight part of the entry is added and f (2) is set in the lock priority part of the entry of the lock priority table 6 corresponding to the task T1. Subsequently, the lock request processing means 1 suspends the processing of the task T2 without calling the lock order changing means 3 because the lock waiting resource name part of the entry of the lock priority table 6 corresponding to the task T1 is empty.

When the task T3 requests the resource R2 in the shared mode at the time t + 2 and the task T4 requests the resource R2 in the exclusive mode at the time t + 3, the processing is performed as in the case of the task T1 and the task T2. The lock right is given to the task T4, and the task T4 waits for the lock. As a result, the exclusive control table 5 and the lock priority table 6 at time ta are in the state of FIG.

When the task T3 makes a lock request for the resource R1 in the shared mode at time t + 4, the lock request processing means 1 is called. Since the resource R1 is already locked in the exclusive mode, the lock request processing means 1 adds the pair of the task identifier T3 of the task and the shared mode to the end of the lock queue corresponding to the resource name part R1. Next, the lock request processing means 1 records the resource name of the resource R1 in the lock waiting resource name part, and calls the lock order changing means 3 using the resource name R1 of the resource as a parameter. Lock order changing means 3
Has task T2 and task T3 lock priorities of f (0) and f (1), respectively, and f (0) <f
From (1), the lock queue is rearranged in the order of the lock request of the task T3 and the lock request of the task T2. That is,
The task T3 overtakes the task T2 that has previously requested the lock, and priority is given to granting the lock right to the task T3. Subsequently, the lock request processing means 1 locks the lock priority setting means 4 because the number of lock requests in the lock queue is not one.
The processing of task T3 is interrupted without calling.
As a result, the exclusive control table 5 and the lock priority table 6 at the time tb are in the state of FIG. 4 (b).

When the task T1 makes an unlock request for the resource R1 at time t + 5, the unlock request processing means 2 is called. The unlock request processing means 2 deletes the task identifier T1 from the locked task list. Next, since the lock queue is not empty, the unlock request processing means 2 locks the task with the task identifier T1 of the task, the resource name R1 of the target resource of the unlock request, and the priority reduction request as parameters. Call the degree setting means 4. The lock priority setting means 4 subtracts the value 2 of the weight part of the entry of the exclusive control table 5 corresponding to the resource name R1 from the sum of weight parts of the entries of the lock priority table 6 corresponding to the task identifier T1 to obtain the task T1. Set f (0) in the lock priority part of the corresponding entry of the lock priority table 6. As a result, the locked task list becomes empty, so
The unlock request processing means 2 erases the lock mode part. Further, since the lock queue is not empty, the unlock request processing means 2 causes task T3 of the first lock request.
Give the lock right to the share mode in the lock mode section,
The task identifier T3 is recorded in the locked task list. Next, the unlock request processing means 2 empties the lock wait resource name part of the lock priority table 6 corresponding to the task T3, and the lock queue is not empty. Therefore, the task identifier T3 and the resource name of the lock request. Lock priority setting means 4 with R1 and the request for priority increase request as parameters
Call. The lock priority setting means 4 adds the value 2 of the weight part of the entry of the exclusive control table 5 corresponding to the resource name R1 to the total weight part of the entries of the lock priority table 6 corresponding to the task T3, and corresponds to the task T3. After setting f (3) in the lock priority part of the lock priority table 6, the processing of task T3 is restarted. As a result, the exclusive control table 5 and the lock priority table 6 at time tc are in the state of FIG.

When the task T3 continuously requests the resources R1 and R2 to unlock at time t + 6, the same processing as the unlock request by the task T1 is performed, and the task T2 in the resource R1 and the task T4 in the resource R2. A lock right is given to each. As a result, the exclusive control table 5 and the lock priority table 6 at the time td are
The state shown in FIG. 4D is obtained.

In the above embodiment, the function f (x) is f
Although it is assumed that the function satisfies (0) <f (1) <f (2) <f (3), a function including a case such as f (a) = f (b) (a <b) Can also be used. This function does not strictly control the lock priority according to the weight sum, but associates one lock priority with a certain range of the weight sum. When the weight sums are not significantly different, the lock right is given on a first-come-first-served basis. Suitable for when you should. When such a function is used, the operation is different except that when the lock queue is rearranged by the lock order changing unit 3, the task having the weight sum b is not prioritized over the task having the weight sum a but is arranged on a first-come-first-served basis. Is the same processing.

In the above embodiment, the case where the weights of the resources are made different has been described, but the weights of the resources may all be fixed to one. In this way, it is suitable when the time average value of the lock queue length of each resource and the lock time average value per time are not so different, and all resources can be treated equally. Further, the process of adding / subtracting the value of the weight part of the exclusive control table 5 to / from the weight sum total part of the lock priority table 6 can be replaced with the process of adding / subtracting the constant 1 to / from the weight sum total part. This allows
The weight part of the exclusive control table 5 can be deleted, and the memory amount required for the exclusive control table 5 can be reduced. The operation is the same as that of the above-mentioned embodiment except that the addition / subtraction processing to the weight summing unit is the above processing.

Further, in the above embodiment, the case where the function f (x) for calculating the lock priority is used has been described, but the function for calculating the lock priority is f (x) = x,
The sum of weights themselves may be used as the lock priority. This is suitable when strict priority control based on the sum of weights is required. Further, by changing the process of adding / subtracting the weight part of the exclusive control table 5 to / from the weight summation part of the lock priority table 6, to directly add / subtract to the lock priority part, the weight summation part of the lock priority table 6 is changed. It can be deleted, and the amount of memory required for the lock priority table 6 and the number of execution steps required for calculating the lock priority can be reduced. The operation is the same as in the above embodiment except that the lock priority calculation process is the above process.

[0032]

As described above, according to the present invention, the lock priority is set so as to increase with an increase in the total weight of the resources for which lock waiting is occurring, and a task having a high lock priority is locked. By controlling so that the lock right is given priority to the task with the lower priority, the lock wait time is set when the task waiting for another task locks a new resource and waits for the lock. Can be reduced, the lock waiting time of other tasks waiting for the lock of the resource locked by the task can be reduced, and the utilization efficiency of the shared resource can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a shared resource exclusive control method according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing configurations of an exclusive control table and a lock priority table in the shared resource exclusive control method of the present embodiment.

FIG. 3 is a lock / unlock timing chart for explaining the operation of the shared resource exclusive control method according to the present exemplary embodiment.

FIG. 4 is a diagram showing the states of the exclusive control table and the lock priority table for explaining the operation of the shared resource exclusive control method according to the present embodiment, in which (a) is the exclusive control table and the lock priority at time ta. The state of the table is shown, (b) shows the states of the exclusive control table and the lock priority table at time tb, and (c) shows the time tc.
Shows the states of the exclusive control table and the lock priority table at (d), and (d) shows the states of the exclusive control table and the lock priority table at time td.

[Explanation of symbols]

 1 Lock Request Processing Means 2 Unlock Request Processing Means 3 Lock Order Changing Means 4 Lock Priority Setting Means 5 Exclusive Control Tables 6 Lock Priority Tables 7 Shared Resource Exclusive Control Functions T1-Tn Tasks R1, R2 Resources

Claims (3)

(57) [Claims] 1. In a shared resource exclusive control method for a computer system, a weight is set in advance for each resource, and the sum x of the weights of the resources in which the task waiting for lock exists among the locked resources of the task Function f (x) (f if a> b
A value calculated by (a) ≧ f (b) is satisfied and c and d satisfying f (c)> f (d) such that c and d are present) is set as a lock priority of the task. A shared resource exclusive control characterized by having lock priority setting means for setting and lock order changing means for rearranging the lock queues so that the lock right is given to the tasks waiting for lock in order of higher lock priority. method. 2. The shared resource exclusive control method according to claim 1, wherein the weight of each resource is fixed to 1. 3. The shared resource exclusive control method according to claim 1, wherein the function is f (x) = x.