JPH03240859A - Multiprocessor shared resource control system - Google Patents

Abstract

PURPOSE:To prevent a shared resource from being abnormally occupied by providing the first means to show whether the shared resource is occupied by any one of processors or not, and the second means to be turned to a certain state different from any previous states each time the processor to occupy the shared resource is changed. CONSTITUTION:When using a shared resource 4, a processor 1 investigates a lock flip-flop 41 of the shared resource 4 and when lock is enabled, a lock counter 42 is incremented. Then, a processing is exerted onto the occupied shared resource 4 and the lock is released. When the lock is disabled since the other processor, for example, a processor 2 already occupies the shared resource 4, the value of a lock counter 2 is read. After starting the possession of the lock, when there is no change in the value of the lock counter 2 even after the lapse of the maximum resource occupation time, the lock counter 42 is incremented and the lock is released.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multiprocessor shared resource management method.

[Conventional technology]

In the shared resource management of multiprocessors, no method has been proposed that allows other processors to detect that a processor is occupying a resource for a period exceeding the maximum occupation time.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for managing shared resources of a multiprocessor, in which when a processor occupies a shared resource for a period exceeding the maximum occupancy time, other processors can unlock the resource.

[Means to solve the problem]

The multiprocessor shared resource management method of the present invention includes a first means for indicating whether or not a resource shared by a plurality of processors is occupied by any of the processors;
and second means for taking a state different from any previous state each time the occupied processor changes.

〔Example〕

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

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

The processors 1, 2.3 are connected to a shared resource 4 via a common address data bus 5. The shared resource 4 includes a lock flip-flop 41 and a lock counter 42 that can be set and reset by the processor.

FIG. 2 is a flowchart of the processing operation of the embodiment shown in FIG. For example, when the processor 1 attempts to use the shared resource 4, it checks the lock flip-flop 41 of the shared resource 4 using a TAS command (101), and if the lock is possible, increments the lock counter 42 by 10.
2) Processes the occupied shared resource 4 (103) and releases the lock (104).

If it is already occupied by another processor, for example processor 2, and cannot be locked, the value of lock counter 2 is read (105). If the maximum resource occupancy time has passed since the start of lock acquisition and there is no change in the value of lock counter 2 (106), lock counter 42 is incremented and the lock is released (108). If the maximum resource occupancy time has not been exceeded or if the value of the lock counter 31 has changed, the process waits for a certain period of time (107).

〔Effect of the invention〕

As explained above, the present invention provides a means for indicating whether a shared resource is occupied, such as a lock flip-flop, and a means for indicating whether or not the occupied processor has changed between two times, such as a lock flip-flop. By having a counter, if a shared resource is abnormally occupied, it can be discovered and released.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
3 is a flowchart of the processing operation of the embodiment shown in the figure. 1.2.3... Processor, 4... Shared resource, 41
. . . lock flip-flop, 42 . . . lock counter, 5 . . . common address data bus.

Claims (1)

[Claims] a first means for indicating whether or not a resource shared by a plurality of processors is occupied by any of the processors; and a second means that takes a state different from any previous state each time the processor that occupies the resource changes. A multiprocessor shared resource management method characterized by comprising means.