JPS58203563A - System for controlling assignment of priority of right - Google Patents

Abstract

PURPOSE:To assign one resource to each requesting source uniformly in a system using the resource by plural requesting sources by providing the system with a right priority assigning circuit to process data. CONSTITUTION:The CPUs 2-5 can use a memory circuit 1 in common through a data bus 7. Memory utilization requesting signal lines 12-15 and memory utilization permission signal lines 8-11 are connected between respective CPUs and a rihgt priority circuit 6. When the CPUs 2, 3 send requests for using the memory 1 to the circuit 6, the circuit 6 accepts the CPU2 using the memory 1 with priority out of the CPUs 2, 3 in accordance with least recently used algorithm and sends a permission signal through a permission signal line 8. Receiving the permission signal, the CPU2 can used the bus 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rights order allocation control method for a system such as a memory circuit that is shared by a requestor such as a microcomputer that uses one resource.

Prior Art In a system in which one resource is shared by multiple requesters, if the request signals generated from each requester overlap, it is necessary to ensure equal use of the resource by determining the order of use. Become. Conventionally, when a request signal arrives at a resource, a response is made to the request source according to a fixed priority order determined in advance based on physical arrangement or the like.

Problems with the conventional technology In the conventional method, since the priority order is constant, request sources with lower priority are always kept waiting for a long time.
This caused an inconvenient problem.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a rights order allocation circuit to ensure equal use of resources for each request source.

Summary of the Invention According to the rights till order allocation method of the present invention, when there is a conflict between a resource, a plurality of request sources arranged to share this resource, and the use of the resource by these plural request sources, the right +1ii1 a right order allocation circuit that performs order allocation control; a request signal line provided between each of the request sources and the right order allocation circuit and set when the request source uses the resource; and a request signal line that is set when the request source uses the resource; the right II and the right order allocation circuit;
and a permission signal line that is set when the order allocation circuit grants a request from the request source. When the resource usage from the request source is the only one, the rights order allocation circuit grants the predetermined permission (line 8) only to the unique request source, and when the resource usage request from the request source is The present invention is characterized in that when a plurality of request sources conflict, the right order allocation circuit sets a permission signal line only for the first request source from among the plurality of request sources.

Embodiment of the Invention FIG. 1 is a block circuit diagram showing an embodiment of the invention. 1 is a memory circuit as a resource, and 2 to 5 are microcomputers or central information processing units (hereinafter referred to as CPUs) indicating request sources. CPU2~5
are in a relationship where they share the resource 1, and are connected by a data bus 7 for transmitting information. Reference numeral 6 denotes a rights order allocation circuit, which has two types of signal lines between each of the CPUs 2 to 5. On the other hand, 8 to 11 are permission signal lines through which the right order allocation circuit 6 sends a signal for permission to use the memory 1 to any one of C1'LIs 2 to 5. On the other hand, 12 to 15 are request signal lines that are set to send a signal to the circuit 6 when the CPUs 2 to 5 want to use the memory 1.

In FIG. 1, when the CPU 2 accesses the memory 1, and then the CPUs 3 and 4.5 send data to the access path 6 in this order, the 5th circuit 6 becomes LRU (LeloRecently).
Used) Output according to the algorithm. In other words, when there was a request to use memory 1, the CPU that used the memory first from PU2 and PU3, in this case, CPU2.
It accepts the request from and sends out a permission signal using permission signal l518.

The CPO 2 that receives this becomes able to use the data bus 7.

FIG. 2 is a block circuit diagram showing the rights order allocation circuit 6 in more detail. In FIG. 2, 16 is an I, RU algorithm circuit which is activated when the enable terminal is set, Among the terminals set in D, only the one that is output first is set as the output terminal. In the above example, the A terminal would be tied to or 8.

Effects of the Invention As explained above, the present invention provides
When PUs share memory, which is a resource, when request sources compete to use the resource, LR,
By using the U algorithm, priority can be given to the earliest requester, and equal priority usage opportunities can be given to each requester without being specified.

[Brief explanation of the drawing]

FIG. 1e is a block circuit diagram showing one embodiment of the present invention, and FIG. 2 is a block circuit diagram showing essential parts of the circuit of FIG. 1. 1...4 memory circuits as resources, 2 to 5...
River/CPU that is the request source, 5... Rights order allocation circuit, 7... Data bus, 8 to 11...
・Permission signal line, 12 to 15...Request signal line, 1
6...I4U algorithm circuit. Agent Patent Attorney Kuri 1) Yu Haru

Claims (1)

[Claims] A resource 1, a plurality of request sources 2 to 5 arranged to share this resource, and a rights order allocation circuit 6 that performs rights order allocation control when there is a conflict in the use of the resource by the plurality of request sources. , request signal lines 12 to 15 provided between each of the request sources and the right order allocation circuit and set when the request source uses the resource.
and permission signal lines 8 to 11 provided between each of the request sources and the right order allocation circuit and set when the right order allocation circuit grants a request from the request source; When the resource usage from the request source is unique, the rights order allocation circuit sets the predetermined permission signal line only for the unique request source, and when there is a conflict of resource utilization requests from the request source, A rights order allocation control method in which a rights order allocation circuit sets a predetermined permission signal line only for the first one of the plurality of request sources.