JPH0340140A - Exclusive control system for shared resources - Google Patents

Abstract

PURPOSE:To shorten the waiting time of the subsequent lock waiting processes by overlapping the swap-in process of a process to a process kept in a lock state in terms of time in a swap-out state of the process and inhibiting the swap-out state. CONSTITUTION:A swap control means 5 accepts a swap-out inhibiting request and a swap-out inhibition canceling request of a designated process and processes these requests. Then a residence request means 2 requests the means 5 to inhibit the swap-out of a process to which the next lock right is given when the present lock is canceled out of those processes kept in the lock waiting state. then a residence cancel request means 3 requests the means 5 to cancel the swap-out inhibition of a process when the process having the lock right at present is kept in a swap-out inhibiting state by the means 2. As a result, the waiting time is shortened for the subsequent lock waiting processes and at the same time the availability of the shared resources is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shared resource exclusive control method, and particularly to a shared resource exclusive control method for a computer system.

[Conventional technology]

In a computer system, exclusive control is required for resources used by multiple processes in order to serialize access to the resources. For such exclusive control, computer systems are equipped with a basic function called lock/unlock (or ENQ/DEC), and there are usually two types of lock requests: exclusive mode and shared mode. be.

The basic operation of exclusive control is as follows. When a process issues a lock request, the lock right is immediately granted if the resource for which the lock request is made is not locked by another process. However, if the resource is already locked by another process and the lock mode of the resource or the lock request mode of the process is exclusive mode, the process waits for the lock. The mouth of its resources.

When both the lock mode and the lock request mode of the process are shared mode, the process is granted the lock right. Furthermore, when a process that has locked a resource issues an unlock request, the exercise of the locking right by that process ends. If there is no other process holding the lock and there is a process waiting for the lock, if the mode of the lock request of the process that requested the lock earliest among the processes waiting for the lock is exclusive mode, only this process will have access rights. If the process is in shared mode, all processes currently waiting for the lock in shared mode are granted the lock right.

Conventionally, this type of shared resource exclusive control method generally does not deal with swapping out processes during the lock/unlock process, or prohibits swap out only during the lock/unlock process. Ta.

[Problem to be solved by the invention]

In the conventional shared resource exclusive control method described above, when the process currently holding the lock requests an unlock and grants the lock to the next process, if the next process has been swapped out, it is swapped in and then locked. However, swap-in requires input/output processing, which increases the waiting time of other lock-waiting processes and reduces resource usage efficiency.

In view of the above-mentioned points, an object of the present invention is to provide a shared resource exclusive control method that reduces the lock waiting time of subsequent lock waiting processes and improves the usage efficiency of shared resources.

[Means to solve the problem]

The shared resource exclusive control method of the present invention is a shared resource exclusive control method for a computer system that includes a swap management means that receives and processes a swap-out prohibition request and a swamp-out prohibition release request of a designated process, and a swap management means that receives and processes a swap-out prohibition request and a swamp-out prohibition release request of a specified process, and a process that is in a lock wait state. resident request means for requesting the swap management means to prohibit swap-out of the process to which the lock right is next granted when the current lock is released; and resident release requesting means for requesting the swasub management means to release the swamp-out prohibition of the process when the process is in a swamp-out prohibited state by the swap requesting means.

[Effect]

In the shared resource exclusive control method of the present invention, the swap management means receives and processes the swank-out prohibition request and the swap-out prohibition release request of the specified process, and the resident request means receives the current lock of the process waiting for the lock. The swap management means is requested to prohibit swamp-out of the process to which the lock right is next granted when the lock is released, and the resident release request means causes the process to which the lock right is currently granted to be swamped out by the resident request means. If the process is prohibited, the swap management means is requested to release the swap-out prohibition of the process.

〔Example〕

Next, the present invention will be explained 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 system of this embodiment consists of exclusive control means 1. The resident request means 2 requests swap-out prohibition of the next lock-waiting process to which the lock right is granted when the current lock is released, and the resident request means 2 requests swap-out of the process to which the lock right is currently granted. A shared resource exclusive control function 4 includes a resident release requesting means 3 that requests cancellation of the swamp-out prohibition when the swamp-out prohibition is prohibited, and a swap-out prohibition request issued from the resident request means 2 and the resident release request means 3; It is comprised of a swap management means 5 for processing swap out prohibition release requests, and a request queue 6 for the swap management means 5.

The exclusive control means 1 performs the same exclusive control as in the past, but when a resource is locked by a certain process and a request is made from another process, the exclusive control means 1 calls the resident request means 2. After that, the process that issued the lock request is placed in a lock wait state. In addition, the exclusive control means is a process for granting the lock right to the next process that should be granted the lock right if the resource is locked by a certain process and the process requests an unlock. After performing this, the resident release request means 3 is called, and subsequently the resident request means 2 is called.

The residency requesting means 2 searches for all processes to which lock rights will be granted next when the current lock is released,
Swap-out prohibition requests for processes that are not yet prohibited from swamp-out are queued in a request queue 6.

When the process to which the lock right is currently granted is placed in a swap-out prohibited state by the resident request means 2, the resident release requesting means 3 queues a swap-out prohibition release request for the process in the request queue 6. do.

The swap management means 5 sends one request from the request queue 6.
In response to a swamp-out prohibition request, (1) if the specified process has already been swapped out, it is swapped in and subsequent swap-outs are prohibited, and (2) if the specified process has not been swapped out. If not, it simply prohibits future swap-outs, and in response to a request to cancel the swamp-out prohibition, cancels the swamp-out prohibition for the specified process.

Next, the operation of the shared resource exclusive control system of this embodiment configured as described above will be specifically explained with reference to FIG.

FIG. 2 is a timing chart showing a situation in which three processes A, B, and C sequentially issue lock requests and unlock requests to resource #R.

Note that it is assumed that all lock requests here are requests in exclusive mode. Further, it is assumed that the resource R is initially in an unlocked state.

At time T1, when process 8 requests a lock on resource/sR, exclusive control means 1 grants the lock right to process A, since resource R is currently not locked.
Complete processing of the lock request.

Next, at time T2, when process B requests a lock on resource R, exclusive control means 1 detects that resource R has already been locked by process A, and calls resident request means 2.

The resident requesting means 2 detects that the process B is the next process to be granted the lock right for the resource aR, queues the request for prohibition of shutdown of the process B in the request queue 6, and sends the exclusive control means 1 to the request queue 6. Return control to.

When control is returned from the resident requesting means 2, the exclusive control means 1 places the process B in a lock waiting state.

The swap management means 5 removes the process B from the request queue 6.
Process B receives a swamp-out prohibition request and prohibits process B from swapping out.

Next, at time T3, when process C requests a lock for resource aR, exclusive control means 1 calls resident request means 2 in the same manner as process B.

Since there is no process that is not prohibited from swapping out among the processes to which the lock right is next granted, the resident requesting means 2 does not do anything and requests the exclusive control means 1.
Return control to.

When control is returned from the resident requesting means 2, the exclusive control means 1 places the process C in a lock wait state.

After this, due to reasons such as increased memory load, process C
is swapped out, and when process A requests an unlock at time T4, the exclusive control means 1 sends process B, which requested the lock earliest from among the lock waiting processes.
After performing the process of granting the lock right to the user, the resident release requesting means 3 is called.

The resident release requesting means 3 detects that process B is currently the process to which the lock right has been granted and that the resident requesting means 2 has set it in the swosubout-prohibited state, and requests process B to release the swamp-out prohibition. The request is queued in the request queue 6 and control is returned to the exclusive control means 1.

When control is returned from the resident release requesting means 3, the exclusive control means 1
For example, the resident request means 2 is then called.

The resident request means 2 detects that the next process to be granted the lock right for the resource HR is process C and that swap-out is not prohibited for process C, and waits for a request to prohibit swap-out to process C. It is queued in matrix 6 and control is returned to exclusive control means 1.

When control is returned from the residency requesting means 2, the exclusive control means 1 completes the processing of the process B's request.

The swap management unit 5 first receives a request for canceling the swap-out prohibition of process B from the request queue 6, cancels the swap-out prohibition of process B, and then cancels the swap-out prohibition of process B.
receives the swap-out prohibition request and attempts to disable swap-out for process C. However, process C
has already been swapped out, so after swapping in process C, the swap management means 5 disables swapping out of process C.

1. At time T5, when process B makes an unlock request, exclusive control means 1 performs processing to grant lock rights to process C, and then calls resident release request means 3.

The resident release requesting means 3 detects that the process C is currently the process to which the lock right has been granted and that it has been placed in a susonopout prohibition state by the resident requesting means 2, and requests a request to release the suwanopout prohibition of the process C. The data is queued in the queue 6 and control is returned to the exclusive control means 1.

When control is returned from the resident release requesting means 3, the exclusive control means 1
Next, calls the resident request means 2.

Since there is no process waiting for the lock, the resident requesting means 2 returns control to the exclusive control means 1 without doing anything.

When control is returned from the resident requesting means 2, the exclusive control means 1 completes processing of the process C lock request.

In the explanation of the operation of the above embodiment, it is assumed that all lock requests are in the exclusive mode, but even if lock requests in the shared mode are mixed, the resident request means 2 and the resident release request means 3 share the lock request. Processing is carried out in the same way, except that a swap-out prohibition request and a swap-out prohibition release request are made to multiple processes that have issued mode lock requests.

In addition, if the swap-out prohibition in this embodiment is treated separately from the swamp-out prohibition during ronoku/unrosoku processing, which has been performed previously, the swamp-out prohibition processing during rosoku/unrosoku processing and the swap-out prohibition in this embodiment can be treated separately. It is also possible to use it in combination with treatment.

〔Effect of the invention〕

As explained above, the present invention prohibits swap-out if the process to which the lock right is next granted when the current lock is released has not been swapped out, and if the process is currently being swapped out, the swap-out is prohibited. The lock waiting time of subsequent lock waiting processes can be reduced by temporarily overriding the swap-in processing of the process and the processing of the process currently in progress, swapping the process in, and prohibiting swap-out. This has the effect of reducing the amount of energy used and improving the efficiency of using shared resources.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a shared resource exclusive control method according to an embodiment of the present invention, and FIG. 2 is a timing chart specifically explaining the operation of the shared resource exclusive control method of this embodiment. In the figure, 1... Exclusive control means, 2... Resident request means, 3... Resident release request means, 4... Shared resource exclusive control function, 5... Swap management means, 6... - It is a request queue.

Claims (1)

[Claims] In a shared resource exclusive control method for a computer system, there is provided a swap management means for receiving and processing a swap out prohibition request and a swap out prohibition cancellation request from a designated process; resident request means for requesting the swap management means to prohibit swap-out of the process to which the lock right is next granted when the lock is released; 1. A shared resource exclusive control method, comprising: resident release requesting means for requesting the swap management means to release the swap-out prohibition of the process when the process is in a swap-out prohibited state.