KR100606701B1 - Hierarchical Arbitration System, Method for arbitrating using the system - Google Patents

Abstract

In the arbitration system, in particular, it relates to a hierarchical arbitration system and an arbitration method using the same to efficiently distribute load in a system having a plurality of shared resources. Multiple pre-selected external access requests based on a plurality of higher arbitrators that control actual access to the request for access to resources and information on the status of access request to the corresponding shared resource provided from the higher arbitrator. The present invention relates to a hierarchical arbitration system including a plurality of subordinate arbitrators each of which is distributed to each of the higher arbitrators and to a hierarchical arbitration method using the same.

Arbitration of Priority Scheme, Arbitration of Round-Robin Scheme, Hierarchical Arbitration System

Description

Hierarchical Arbitration System, Method for arbitrating using the system

1 is a block diagram showing a part of a general hierarchical arbitration system.

2 is a block diagram illustrating a detailed configuration of an upper arbiter in a general hierarchical arbitration system.

Figure 3 is a block diagram showing a conventional hierarchical arbitration system configuration having a plurality of independent shared resources.

4 is a block diagram illustrating a general configuration of a lower arbiter in a hierarchical arbitration system having independent multiple shared resources.

5 is a block diagram illustrating a general configuration of a higher arbiter in a hierarchical arbitration system having independent multiple shared resources.

6 is a block diagram showing the configuration of a lower arbiter in a hierarchical arbitration system according to the present invention;

7 is a block diagram showing the configuration of an upper arbiter in a hierarchical arbitration system according to the present invention;

8 is a flowchart illustrating a method for arbitrating a hierarchical structure according to the present invention.

* Description of the symbols for the main parts of the drawings *

500: sub-level arbiter

540: upper arbitration interface unit

700: top-level arbiter

740: resource access control

800: shared resources

The present invention relates to an arbitration system, and more particularly, to an arbitration system having a hierarchical structure and an arbitration method using the same for efficiently distributing load in a system having a plurality of shared resources.

In general, any system consists of a number of modules, depending on the purpose of the system, and these modules, when given inputs, generate an appropriate output by exchanging information with each other.

At this time, among the resources constituting the system may be a module shared by a number of different modules, for example, may be a memory.

In the case of resources shared by many different modules, such as memory, an arbiter is required to mediate access to these resources, and various types of arbitration algorithms are provided according to each module's approach. ) Is used.

Representative arbitration algorithms include a priority scheme and a round-robin scheme.

If you want to give a fair chance to all requesters (hereinafter referred to as requesters) among them, use the round robin structure, and if you want to give priority to each requester. In default, the priority structure is used.

In addition, various modified arbitration algorithms based on these round robin structures and priority structures are used, one of which is hierarchical arbitration.

In this hierarchical mode of arbitration, when there are a large number of requests for access to shared resources, they are divided into several groups, and then arbitration is first performed for each group. Thereafter, mediation is performed again between access requests selected from each group.

1 is a block diagram showing some components of a general hierarchical arbitration system.

Referring to FIG. 1, the request for access to the shared resource 30 is mediated once by the sub-level arbiters 10, 11, and 12, respectively.

According to the arbitration results in the lower arbitrators 10, 11 and 12, one request (Req [1], Req [2], Req [n]) is selected for each lower arbitrator 10,11,12. Once selected, the request is passed back to the top-level arbiter 20.

The upper arbiter 20 arbitrates again among the requests received from the lower arbiters 10, 11, and 12, and finally selects one request.

Afterwards, a real access to the service, that is, the shared resource 30, is made for the final selected request, and common data or dedicated data according to a common address / command or a dedicated address / command are exchanged between the shared resource and the requester.

In this case, when a request queue is not present in the upper arbiter 20, when the service is completed, the arbitration for each request is again sent to the lower arbiters 10, 11, 12 and the upper arbiter 20. However, if there is a request queue in the upper arbiter 20, arbitration for each request is attempted again when the last selected request can be loaded into the request queue.

The detailed configuration of the upper arbitrator for explaining such an operation is shown in FIG.

FIG. 2 is a diagram illustrating a detailed configuration of an upper arbiter in a general hierarchical arbitration system. The upper arbiter 20 illustrated in FIG. 2 generally includes a request queue 23.

In general, each requester (not shown) drives the access request signal Req [I] to the upper arbiter 20, and the upper arbiter 20 responds to the access grant signal grn in response thereto. Arbitration is done by driving [I]).

Also, the requester (not shown) shows that the priority signal pri [I] is driven, which assumes a case where a priority structure arbitration method is used.

First, when the access request signal Req [I] is driven to the upper arbiter 20, the Winner Determining Block 22 selects one access request.

Thereafter, the information on the selected access request is stored in the request queue 23, and the actual access to the shared resource is performed by the control signal of the resource access control unit 24.

1 and 2, however, a plurality of shared resources may be independently configured according to a system. That is, when one requester is accessing one shared resource, the other requester can access other shared resources at the same time.

As shown in FIG. 3, a hierarchical arbitration system having a plurality of independent shared resources is illustrated.

3 is a block diagram showing a conventional hierarchical arbitration system configuration having a plurality of independent shared resources. When the shared resources 70, 71, 72 are independent, each shared resource 70, 71, 72 is illustrated. There are mediators that mediate access to the control panel and control the actual access to each shared resource (70, 71, 72).

That is, as shown, a plurality of higher arbitrators 60, 61, and 62 are provided to control access to each shared resource 70, 71, and 72.

However, when the lower level mediation is performed after the lower level arbitration in the arbitration system having a plurality of shared resources 70, 71, and 72, access to the shared resources becomes difficult.

This is because the requests initially selected in the lower arbiters 40, 41, and 42 may be concentrated in a small number of shared resources instead of being distributed throughout the shared resources.

4 is a block diagram illustrating a general configuration of a lower arbiter in a hierarchical arbitration system having independent multiple shared resources.

Referring to FIG. 4, generally, each requester (not shown) drives an access request signal Req [i] [j] to the lower arbiter 100, and the lower arbiter 100 In response, arbitration is performed by driving an access grant signal grn [i] [j].

Here, it is shown that the requester (not shown) drives the priority signal pri [i] [j], which assumes the case of using an arbitration method of priority structure.

First, when the access request signal Req [i] [j] is driven to the lower arbiter 100, the Winner Determining Block 120 selects one access request.

Thereafter, the information on the selected access request is stored in the request queue 130 and is transmitted to the upper arbiter 300 by the upper arbitration interface unit 140.

At this time, the request signal Req_k [i] is driven by the second switch 220 according to the access area mainly determined by the address, and at this time, the upper arbitrator 300 access permission signal for the request ( As grn_k [i]) is driven, the lower arbiter 100 transmits information necessary for access to the shared resource stored in the request queue 130 to the upper arbiter 300.

FIG. 5 is a block diagram illustrating a general configuration of a higher arbiter in a hierarchical arbitration system having independent multiple shared resources.

Referring to FIG. 5, when the access request signal Req_k [i] for the corresponding request selected by the lower arbiter 100 is driven to the upper arbiter 300, the upper arbiter 300 permits access to the upper arbiter 300. Arbitration is accomplished by driving signal grn_k [i].

Here, it is shown that the lower arbiter 100 drives the priority signal pri_k [i], which also assumes a case of using an arbitration scheme having a priority structure.

First, when the access request signal Req [i] [j] is driven from the lower arbiter 100 to the upper arbiter 300, the Winner Determining Block 320 selects one access request. .

Thereafter, the information on the selected access request is stored in the request queue 330, and the actual access to the shared resource is made by the control signal of the resource access control unit 340.

4 and 5, when there are a plurality of shared resources, a request selected first by the lower arbiter 100 may be a higher arbitration corresponding to a shared resource determined according to an access region whose request is mainly determined by an address. Delivered to machine 300.

Even in such a case, since the requests primarily selected by the lower arbiter 100 may be concentrated on a few shared resources instead of being distributed as a whole shared resource, access to efficient shared resources is difficult.

Therefore, in the case where requests are concentrated to some shared resources, not only the latency of requests for the shared resources to which the requests are concentrated increases but also the access to the requests to other shared resources. The bandwidth required for access is increased.

This is not a problem if the bandwidth used to access the shared resource is much larger than necessary, but generally this is not so. Insufficient there is a problem that causes a malfunction of the entire system.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and in order to distribute the access to the shared resources evenly in a system having a plurality of shared resources, a plurality of sub-arbiters are assigned to a higher arbiter ( It is to provide a hierarchical arbitration system and a method of arbitration using the hierarchical structure that performs arbitration for a plurality of requests by reflecting the information on the access request status provided by the top-level arbiter.

A feature of the hierarchical arbitration system according to the present invention for achieving the above object is that, in any system having a plurality of shared resources, a number of higher levels that control the actual access to access requests to each shared resource. The mediator receives information on the access request status to the corresponding shared resource from the higher arbitrator, performs arbitration on a plurality of external requests, and distributes the access requests to the shared resources selected accordingly. It consists of a number of subordinate arbitrators passing to the superior arbitrator.

In addition, a feature of the hierarchical arbitration method according to the present invention for achieving the above object is that, as a number of requests for access to shared resources in the arbitration system including a plurality of sub-arbiters and a plurality of higher arbitrators, In arbitrating an access request to a corresponding shared resource, the plurality of sub-arbitrators respectively selecting any access request among the generated plurality of access requests, and access request of the corresponding shared resource for accessing the selected request. Receiving and analyzing a status from the upper arbiter, arbitrating the selected access request to the upper arbiter according to the analysis result, and performing actual access to the corresponding shared resource according to the mediated request. It is to include the step.

Hereinafter, a preferred embodiment of a hierarchical arbitration system and a mediation method using the same according to the present invention will be described with reference to the accompanying drawings.

6 is a block diagram illustrating a configuration of a lower arbiter in a hierarchical arbitration system according to the present invention.

Referring to FIG. 6, a configuration of a load balancer lower arbiter 500 in a hierarchical arbitration system having a plurality of shared resources is shown.

In the present invention, unlike the arbitration system illustrated in FIGS. 4 and 5, the lower arbiter 500 receives its information on the access request state from the upper arbiter 700 to the corresponding shared resource 800, and then arbitrates its arbitration. Is to use.

That is, the request selector 520 of the lower arbiter 500 may reduce the concentration of access requests to a specific shared resource by using the information on the access request state to the shared resource 800.

At this time, the signal used to deliver information about the access request status to the lower arbiter 500 is as follows.

"Req_stat [k]" is a signal indicating the access request status to the k-th upper arbitrator and indicates the number of access request signals Req_k [i], that is, the number of events being requested to access to the k-th upper arbitrator.

However, in case of using the priority structure arbitration method, "Req_stat [k]" can be defined as the priority value (pri_k [i]) of the signal having the highest priority among the signals (Req_k [i]) currently being requested for access. Can be.

"Queue_stat [k]" is a signal indicating the situation of allowing access to the actual shared resource under the control of the kth upper arbitrator, and indicates the number of requests waiting to access the corresponding shared resource.

7 is a block diagram showing the configuration of a higher arbiter in a hierarchical arbitration system according to the present invention.

Referring to FIG. 7, a configuration of a load balancing upper arbiter 700 in a hierarchical arbitration system having a plurality of shared resources is shown.

In the present invention, unlike the arbitration system shown in Figs. 4 and 5, the upper arbiter 700 provides the lower arbiter 500 with information about the current access request status to the corresponding shared resource 800. To make the lower arbiter 500 available for arbitration.

That is, the request latch unit 710 transmits "Req_stat [k]" indicating the number of events currently being requested to access to the upper arbitrator 700 to the lower arbiter 500, and the request queue 730 currently transmits the corresponding. This information is made available to the lower arbiter 500 by passing "Queue_stat [k]", which indicates the number of requests awaiting actual access due to the control of the upper arbiter 700 allowing access to the actual shared resources. To make it work.

8 is a flowchart illustrating a method for arbitrating a hierarchical structure according to the present invention, which will be described with reference to FIGS. 6 and 7.

First, the lower arbiter 500 monitors an access request signal Req [i] [j] from requests (not shown) when idle, i.e., ready for arbitration (S10). .

At this time, if one or more requests occur, the request having the highest priority is selected using the scheme of priority structure (S20, S30).

Thereafter, the lower arbiter 500 receives and receives information (Req_stat [k], Queue_stat [k]) of the access request status of the corresponding shared resource to which the selected request is to be accessed from the upper arbiter 700. (S40).

Accordingly, the lower arbiter 500 analyzes the information provided to know how many access requests are currently in the corresponding shared resource 800 to be accessed, and how many requests are already waiting to be accessed. do.

If the upper arbiter 700 uses an arbitration scheme of priority structure, by comparing the priority of the access request selected by the lower arbiter 500 with the priority of other requests currently being accessed, The mediation results in the higher arbitrator 700 can be expected.

Therefore, it is very likely that the arbitration of the upper arbiter 70 fails to access the access request selected by the lower arbiter 500, or the access requests currently waiting in the request queue 730 of the upper arbiter 700 are In the case of a high probability of arbitration failure, that is, when an access request is busy, the priority of the request already selected by the lower arbiter 500 is lowered, and the mediation by the lower arbiter 500 is attempted again. (S60, S30).

When the mediation is attempted by the lower arbiter 500 again, another access request is selected, and information on the access request status of the corresponding shared resource to be accessed by this reselected request (Req_stat [k], Queue_stat [k). ]) Is received from the upper arbitrator 700 and then latched.

Thereafter, if the upper arbiter 700 is not busy according to the analysis result, the upper arbiter 700 drives the access request signal Req_k [i] to the upper arbiter 700 to participate in the arbitration (S70).

When the mediation by the upper arbitrator 700 is performed and access to the corresponding shared resource is allowed, the access to the shared resource is actually performed to receive the corresponding service (S80).

As described above, according to the hierarchical arbitration system and the arbitration method using the hierarchical structure, a plurality of sub-arbiters are provided in a top-level arbiter in a system having a plurality of shared resources. Since the arbitration is performed by reflecting the information on the access request situation, the arbitration of multiple requests can be evenly distributed.

Therefore, it is possible to reduce the phenomenon that the access request is concentrated to a specific shared resource, thereby preventing system malfunction due to lack of system bandwidth, thereby improving the performance of the entire system.

Claims (5)

A plurality of higher arbiters for controlling actual access to access requests for each shared resource in any system having a plurality of shared resources; 12. A system comprising a plurality of lower arbiters for arbitrating the upper arbiters based on information on a status of a request for access to a corresponding shared resource received from the upper arbiters; And the plurality of lower arbitrators arbitrate each of a plurality of external access requests previously selected and arbitrate to the upper arbitrator. The method of claim 1, wherein the sub-arbitrator, The plurality of generated access requests are respectively selected in order of priority, and the arbitration of the upper arbiter with respect to the access request selected by the lower arbiter is likely to fail, or is currently present in the request queue of the upper arbiter. When there is a high probability of arbitration failure due to a large number of pending access requests (busy), the hierarchical structure characterized by lowering the priority of the request already selected by the sub-arbitrator to retry the arbitration by the sub-arbitrator again. Arbitration system. The method of claim 1, wherein the sub-arbitrator, The number of events requesting access to each of the plurality of higher arbitrators; Information about the number of requests waiting for actual access to the shared resource; And at least one or more pieces of information on the priority of the events being requested to access to each of the plurality of higher arbitrators are provided from the respective higher arbitrators. In arbitrating a mediation system including a plurality of subordinate arbitrators and a plurality of higher arbitrators, in the arbitration of these access requests to the shared resources, The plurality of sub-arbitrators respectively selecting any one of the generated plurality of access requests; Receiving and analyzing an access request state of a corresponding shared resource for accessing the selected request, from the higher arbiter; Mediating the selected access request to a corresponding higher arbiter according to the analysis result; Performing physical access to the shared resource in accordance with the mediated request; And arranging each of the plurality of predetermined external access requests and arbitrating to the upper arbitrator. The method of claim 4, wherein The plurality of generated access requests are respectively selected in order of priority, and the arbitration of the upper arbiter with respect to the access request selected by the lower arbiter is likely to fail, or is currently present in the request queue of the upper arbiter. If there is a high probability of arbitration failure due to a large number of pending access requests (busy), the hierarchical structure characterized in that the priority of the request already selected by the subordinate arbiter is lowered so as to retry the arbitration by the subordinate arbiter again. Arbitration Method.

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