JPH0452929A - Check point save processing system - Google Patents

Abstract

PURPOSE:To shorten the task holding time by enabling a task to access save information in the middle of check point save processing. CONSTITUTION:A memory release means 17 checks a check point processing indicating means 11-2 of a management information block whose release is requested, when the check point processing is not executed, the release processing of the management information block is executed, and when the check point processing is executed at present, one is subtracted from the value in a reference counter 11-1 of the management information block, and it is checked whether a check point write means 14 is the release request source or not, and the processing is terminated when it is not the release request source. When it is the release request source, indication of the check point processing in the check point processing indicating means 11-2 is erased, and the processing is terminated if the value of the reference counter 11-1 of the management information block is not 0, but otherwise, the release processing of the management information block is executed. Thus, the task holding time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conflict processing method between checkpoint save processing and access to task save information in a computer system.

[Conventional technology]

Conventionally, in electronic computer systems, when a malfunction occurs, the first step is to attempt re-execution and recovery using hardware. If hardware re-execution and correction fails, it is left to software recovery processing. The software identifies the task that malfunctioned due to a failure, stops execution of only that task, and continues operating the system. A malfunctioning task is restarted by checkpoint recovery. For this reason, a checkpoint is prepared at an appropriate location within a task, and the program state information at that checkpoint is stored in advance in a storage device. Conventionally, while the program state information is being saved at this checkpoint, tasks are prohibited from accessing the state information. This is because the state information is rewritten from the middle due to task access, causing data inconsistency.

[Problem to be solved by the invention]

In the conventional checkpoint saving processing method described above, since writing is required to a file, the task hold time becomes relatively long, resulting in a decrease in the processing capacity of the entire system.

An object of the present invention is to enable a task to access state information of a target to be saved during the save process at a checkpoint, and to shorten task hold time.

[Means to solve the problem]

The present invention provides a checkpoint saving processing method for saving management information blocks accumulated in an information storage means used by a task at a checkpoint of a task in a computer system to a secondary storage device, the present invention provides management information in the information storage means. a reference counter prepared for each information block and indicating the usage status of the management information block; a writability display means prepared for each management information block and indicating whether the management information block is writable; and the management information block. checkpoint processing means for receiving a checkpoint save processing request from the task; is activated by the point processing means, and increments the reference counter corresponding to all the management information blocks used by the task by 1, and when the display by the writability display means corresponding to the management information block is writable. After setting the writability display means corresponding to the management information block to a writable state and further setting an indication that the management information block is undergoing checkpoint processing on the checkpoint processing display means, control is turned to the checkpoint processing state. checkpoint setting means for returning to the point processing means;
The checkpoint processing means to which control has been returned by the checkpoint setting means is started, and for all the management information blocks used by the tasks, the management information blocks are stored in a checkpoint file on the secondary storage device. checkpoint writing means for issuing an IO command to write to the file and outputting a memory release request signal for the management information block after completion of writing to the file; and the checkpoint writing means outputting the memory release request signal for all the management information blocks. checkpoint completion notification means that is activated by the checkpoint writing means after the output and outputs a checkpoint save processing completion signal to the task that has requested the checkpoint save processing; and a write-disabled state in the checkpoint setting means. The task is activated when the task that requested the checkpoint processing accesses the management information block that has been set to a memory write fault and causes a memory write fault. The value obtained by subtracting 1 from the reference counter value of the management information block that caused the memory write fault is set as the value of the reference counter of the newly secured management information block, and the memory A checkpoint fault that sets the value of the reference counter of the management information block that caused the write fault to 1, allocates the newly secured management information block to the task that caused the memory write fault, and causes the task to re-execute. and a processing means, which is activated when a memory release request for the management information block used by the task is received from the task or the memory release request signal for the management information block is received by the checkpoint writing means; The checkpoint processing display means of the management information block for which release has been requested is checked, and if the checkpoint is not in progress, the management information block is released, and if the checkpoint is in progress, the reference counter of the management information block is checked. Subtract 1 from the value of , then check whether the release request source is from the checkpoint writing means, and if different, terminate the process, and if the release request source is the checkpoint writing means, display the checkpoint processing in progress. If the value of the reference counter of the management information block is not 0, the process is terminated, and if the value of the self-reference counter is 0, the memory is used to release the management information block. It is characterized by being equipped with a release means.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
5 to 5 are processing flowcharts in this embodiment.

FIG. 2 is a processing flowchart of the checkpoint processing means 12 that receives a checkpoint save processing request from the task 10. The checkpoint processing means 12 activates the checkpoint setting means 13. The reference counter 11-1 prepared for each management information block (not shown) in the information storage means 11 used by the checkpoint setting means 13 and the cross section 10 is plus IL (SIO),
Next, the writability display means 11-3 checks whether the management information block is writable (S20). If writable, the management information block is set to a writable state, and a display indicating that the management information block is undergoing checkpoint processing is set on the checkpoint processing display means 11-2 (S30). Information storage means 1 used in task 10
S10 to S3 for all management information blocks in 1
Check whether processing of 0 is completed.

(S40). When the processing of S10 to S30 is completed for all management information blocks in the information storage means 11, the checkpoint writing means 14 is activated (S50).

What is shown in FIG. 3 is checkpoint writing means 1.
4 is a processing flowchart. First, 10 instructions are issued to write the management information block in the information storage means 11, which is the target of the checkpoint, to the checkpoint file on the secondary storage device 18 (31, 10). Next, it waits for the completion of writing to the file (3120). A request is made to the memory release means 17 to release the management information block for which writing has been completed (8130). 5 for all management information blocks in the information storage means 11 used by the task.
Check whether the processing from 110 to 5130 is completed 7.
If not completed, repeat from 5LIO (S140
). 5ilo to 8130 for all management information blocks
When the process is completed, checkpoint completion notification means 1
Task 1 that requested checkpoint evacuation processing in step 5
0 of the completion of checkpoint save processing (S1
50).

What is shown in FIG. 4 is the checkpoint setting means 13.
This process was started by task 10 when a task requesting checkpoint processing accessed the management information block in the information storage means 11 on the main memory that was made write-disabled in , and caused a write fault. The checkpoint fault processing means 16 copies the contents of the management information block that caused the memory write fault to the newly secured management information block in the information storage means 11 (S210). Next, the reference counter 11 of the management information block that caused the memory write fault is
The value obtained by subtracting 1 from the value of -1 is set as the value of reference counter 11-1 of the newly secured management information block, and the value of reference counter 1 of the management information block that caused the memory write fault is set as the value of reference counter 11-1 of the newly secured management information block.
The value of 1-1 is set to 1 (S220). Next, the newly secured management information block is assigned to the task 10 that caused the memory write fault (3230), and the task is re-executed (S240).

What is shown in FIG. 5 is the process when the task 10 or the checkpoint writing means 14 issues a request to release the management information block in the information storage means 11, and the memory activated by the task 10 or the checkpoint writing means 14 The release means 17 checks the display of the management information block requested for release during the checkpoint using the checkpoint processing display means 11-2 (
S310). If the checkpoint is in progress, subtract 1 from the value of the reference counter 11-1 of the management information block for which the release request was made (S320).Next, it is checked whether the release request source is the checkpoint writing means 14, and if it is different, the process is terminated. Ends (8330). If the source of the release request is the checkpoint writing means 14, the display during the checkpoint is erased (5340), but if the value of the reference counter 11-1 of the management information block for which the release was requested is 0. The process ends (S350). If the display of the management information block requested to be released during the checkpoint is not at the checkpoint, or if the value of the reference counter is O in 5350, the management information block is released (S360).

〔Effect of the invention〕

As described above, according to the present invention, by allowing a task to access the save information during checkpoint save processing, it is possible to shorten the task hold time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
5 to 5 are processing flowcharts in this embodiment. 10...Task, 11...Information storage means, 11-1
... Reference counter, 11-2... Checkpoint processing display means, 11-3... Writability display means, 12... Checkpoint processing means, 13...
Checkpoint setting means, 14... Checkpoint writing means, 15... Checkpoint completion notification means, 16... Checkpoint fault processing means,
17...Memory release means, 18...Secondary storage device.

Claims (1)

[Claims] In a checkpoint saving processing method that saves management information blocks accumulated in an information storage means used by the task to a secondary storage device at a checkpoint of a task in a computer system, for each management information block in the information storage means. A reference counter provided for indicating the usage status of the management information block; a writability display means provided for each management information block and indicating whether the management information block is writable; a checkpoint processing display means for displaying that the management information block is undergoing checkpoint processing, and a checkpoint processing means that receives a request for saving the checkpoint from the task; The reference counter corresponding to all the management information blocks that are activated and used by the task is incremented by 1, and if the display by the writability display means corresponding to the management information block is writable, the management information block after setting the writability display means corresponding to the write possibility display means in a writable state and further setting the checkpoint processing display means to indicate that the management information block is undergoing checkpoint processing, control is transferred to the checkpoint processing means. The checkpoint setting means is activated by the return checkpoint setting means and the checkpoint processing means to which control has been returned by the checkpoint setting means, and for all the management information blocks used by the task, the management information blocks are checkpoint writing means for issuing an IO command to write to a checkpoint file on a secondary storage device and outputting a memory release request signal for the management information block after completion of writing to the file; checkpoint completion notifying means that is activated by the checkpoint writing means after outputting the memory release request signal for the information block and outputting a checkpoint save processing completion signal to the task that requested the checkpoint save processing; It is activated when the task that requested the checkpoint processing accesses the management information block that has been set to the write-disabled state by the checkpoint setting means and causes a memory write fault, and The content of the management information block is copied to the newly secured management information block, and the value obtained by subtracting 1 from the reference counter value of the management information block that caused the memory write fault is used as the newly secured management information. The value of the reference counter of the block is set to 1, the value of the reference counter of the management information block that caused the memory write fault is set to 1, and the newly secured management information block is transferred to the task that caused the memory write fault. a checkpoint fault processing unit that re-executes the task; and a memory release request for the management information block used by the task from the task, or a checkpoint write unit that requests the memory of the management information block to be re-executed. It is activated when a release request signal is received, checks the checkpoint processing display means of the management information block for which the release request has been made, and if the checkpoint is not in progress, performs release processing for the management information block, and the control information block is in the checkpoint state. If,
Subtract 1 from the value of the reference counter of the management information block, then check whether the release request source is from the checkpoint writing means, and if it is different, terminate the process, and confirm that the release request source is from the checkpoint writing means. If the value of the reference counter of the management information block is 0, the process is terminated, and if the value of the reference counter of the management information block is 0, the display of the checkpoint in the checkpoint processing display means is deleted. 1. A checkpoint save processing method comprising: memory release means for releasing information blocks.