KR101167245B1 - Method and apparatus for arbitrating bus using arbitration parameter changed in real-time - Google Patents

Abstract

A bus arbiter and a bus arbitration method are provided that can arbitrate bus masters according to the result of real-time monitoring of the situation of the system-on-chip bus system. Each bus master generates a bus request signal and occupies the bus in response to a bus request grant signal generated corresponding to the bus request signal. The bus arbiter includes a bus monitoring unit for monitoring at least one of bandwidth demand and latency of bus masters in real time and outputting a monitoring signal, a parameter table for storing arbitration parameters, and an arbitration parameter based on the monitoring signal received from the bus monitoring unit An arbitration policy decision unit for determining an arbitration policy related to a priority using an arbitration parameter, and an arbitration policy decision unit for determining a bus request permission based on the arbitration policy and parameters stored in the parameter table received from the arbitration policy decision unit, And a permission determination unit for generating a signal. Since the operation status of bus masters can be reflected in bus arbitration, it meets various user demands.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus arbitration apparatus and an arbitration method using arbitration parameters changed in real-

1 is a block diagram conceptually showing the operation of a bus arbiter according to the prior art.

2 is a block diagram conceptually illustrating an operation of a bus arbiter according to an embodiment of the present invention.

3 is a flowchart showing a bus arbitration method according to another aspect of the present invention.

4 is a flow chart showing in detail the arbitration parameter update step shown in FIG.

The present invention relates to a bus arbiter and a bus arbitration method in a system on a chip (SOC) system, and more particularly, to a bus arbitrator and a bus arbitration method in a system on a chip And more particularly, to a bus arbitration apparatus and bus arbitration method capable of real-time monitoring of the state of a bus in operation and changing the allowable bus occupancy amount or priority in real time.

In order to process various information, information processing apparatuses such as image processing apparatuses use a bus to transmit and receive data and control signals. Components of various devices such as a signal processing unit, a control unit, and a user's operation unit can be interconnected to transmit information through such a bus. Various components share a single or a small number of buses, thereby reducing the manufacturing cost of the apparatus and reducing the size of the layout. However, since several components share the same bus, a collision occurs when several devices attempt to access the same bus at the same time. In the event of a collision, valuable data can be lost, and the overall data processing speed is delayed, so it is important to have an arbitration method that allows multiple components to access the same bus without collision.

1 is a block diagram conceptually showing the operation of a bus arbiter according to the prior art.

The SOC bus system shown in Fig. 1 includes a bus for inputting and outputting data from main memory, three bus masters for accessing the bus, a bus arbiter for efficient access to the bus, and a memory interface. The bus arbiter also includes an arbitration policy storage unit, a parameter table, and an authorization decision unit. The arbitration policy storage unit stores various arbitration algorithms that can be applied to the SOC bus system shown in FIG. 1 in hardware. The parameter table stores arbitration parameters to be applied to various arbitration policies stored in the arbitration policy store. The arbitration parameters include values such as priority, bus occupancy, location of the level in the multilevel structure, and the like. The grant decision unit selects one of the plurality of bus request signals using the arbitration policy selected from the arbitration policies stored in the arbitration policy storage unit to grant access.

There are various methods of arbitration policy. Typical examples of the arbitration policy include a fixed priority method, a round robin method, and a time division multiplexing (TDM) method. In general, only one arbitration policy is applied to one SOC bus system, but one or more arbitration policies may be combined and applied to manage buses more efficiently.

However, in the bus arbiter shown in FIG. 1, the arbitration policies stored in the arbitration policy storage and the arbitration parameters (priority, occupancy allowable amount, etc.) stored in the parameter table are generally specified or fixed. For example, assume that bus master 1 and bus master 2 are operating and that bus master 1 requests more bus usage rights at a particular point in time during the entire operating time, while at another point bus master 2 requests more bus usage rights. In this case, the bus arbiter shown in FIG. 1 can not give higher priority to either bus master 1 or bus master 2 because the parameter values necessary for the arbitration method are not changed in real time. Further, as the number of bus masters increases, it becomes more difficult to set the optimum arbitration parameters. In addition, the set priorities are also difficult to exactly meet the demands of bus masters whose demand varies in real time while the SOC bus system is operating.

That is, the conventional method, in which the arbitration method or the parameter values necessary for arbitration are fixed, is not suitable for effectively arbitrating the uneven and varying complex memory access patterns of the bus masters. As the system becomes more and more complex, the bandwidth required amount of data required by each bus master is gradually increasing, and the memory access pattern is becoming more and more complicated to perform complicated functions. Therefore, in order to satisfy these various requirements, it is necessary to efficiently perform the arbitration operation within a limited bus bandwidth, and also to monitor the access patterns of the masters in real time to find the most ideal arbitration parameter values at that time.

Therefore, as an arbitration technique for efficiently arbitrating a plurality of bus masters, there is a desperate need for a technique for updating arbitration parameters close to real time according to the operation status and controlling bus masters using updated arbitration parameters.

It is an object of the present invention to provide an apparatus and method for monitoring various bus masters of bus masters in real time in a structure of an SOC bus system to be connected to various bus masters to access memory, will be.

It is another object of the present invention to provide a bus arbitration method capable of improving bus performance by varying arbitration parameters necessary for bus arbitration.

Yet another object of the present invention is to provide a bus arbiter which improves the arbitration efficiency by separately mediating the bus master with the required latency value of the bus request and the bus master whose average bus occupancy is important.

According to an aspect of the present invention, there is provided a bus arbitration apparatus for arbitrating a plurality of bus masters that generate a bus request signal and occupy a bus in response to a bus request permission signal generated in response to a bus request signal, A bus arbitration apparatus according to an aspect of the present invention includes a bus monitoring unit for monitoring at least one of a bandwidth requirement and a latency of bus masters in real time and outputting a monitoring signal, And a bus arbiter for updating the arbitration parameters of the bus masters and selectively transmitting the bus request grant signal to the plurality of bus masters in accordance with the updated arbitration parameters and a predetermined arbitration policy. In particular, the bus arbiter according to one aspect of the present invention includes a parameter table for storing arbitration parameters, a parameter update unit for updating an arbitration parameter based on the monitoring signal received from the bus monitoring unit, an arbitration policy And an authorization decision unit for generating a bus request permission signal based on the arbitration parameters stored in the arbitration policy and parameter table received from the arbitration policy decision unit.

According to another aspect of the present invention, there is provided a method for controlling bus occupancy of a plurality of bus masters, which generates a bus request signal and occupies a bus in response to a bus request permission signal generated in response to the bus request signal, A bus arbitration method according to another aspect of the present invention includes a monitoring step of monitoring prioritization information for determining priorities of bus masters in real time based on monitored prioritization information, An arbitration step for arbitrating the bus occupation of a plurality of bus masters by selectively transmitting a bus request permission signal to a plurality of bus masters according to an updated arbitration parameter and an updated arbitration parameter and a predetermined arbitration policy . In particular, the priority determination information is at least one of a bandwidth requirement and a latency of the bus masters. In addition, when the priority determination information includes the bandwidth requirement and the latency of the bus masters, the updating step selects the priority determination information that is more important than the bandwidth requirement and the latency, And updating the arbitration parameter based on the comparison result.

According to the present invention, arbitration parameters used to arbitrate bus masters can be monitored in real time, the optimal arbitration policy can be determined using the monitored results, and the arbitration parameters can be updated, thereby improving the arbitration efficiency of the SOC bus system .

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. In each drawing, the same reference numerals denote the same members.

2 is a block diagram conceptually illustrating a bus arbitration apparatus according to an embodiment of the present invention.

The SOC bus system 200 shown in FIG. 2 includes first to third bus masters 212, 214 and 216, a bus monitoring unit 220, a bus 230, a bus arbiter 250, 290). The bus arbiter 250 includes a parameter update unit 280, an arbitration policy determination unit 260, a parameter table 270, and an authorization decision unit 240.

The bus masters send a bus request signal to the bus arbiter 250 and access the bus 230 when a corresponding bus request grant signal is received. Although the first to third bus masters 212, 214, and 216 share the same bus 230, only one specific bus master among the first to third bus masters accesses the bus 230 at a particular point in time . The bus master may be a general purpose and a dedicated DMA controller (Direct Memory Access Controller).

The bus monitoring unit 220 monitors the states of the first to third bus masters 212, 214, and 216 in real time. That is, the bus monitoring unit 220 monitors a request amount and a latency of a bus ownership in a predetermined section. In this specification, the amount of request for bus use right refers to the amount of bandwidth demanded by the bus master on average for data transmission, and the latency means the time from when the bus master requests the use right to receive the bus request permission signal from the bus arbiter 250 It represents the time taken until the point of time. If the latency is too long, the priority of the corresponding bus master is too low to cause starvation, so that the bus monitoring unit 220 also monitors the latency. 2, the bus monitoring unit 220 is shown as monitoring all of the first to third bus masters 212, 214 and 216, but this is merely exemplary. That is, a plurality of bus monitoring units 220 may exist corresponding to the respective bus masters.

The bus monitoring unit 220 transfers this information to the parameter updating unit 280 in the bus arbiter 250. The parameter update unit 280 analyzes the bandwidth requirement and the latency received from the bus monitoring unit 220, and updates the arbitration parameters assigned to the bus masters based on the analyzed bandwidth demand and latency. The updated arbitration parameter is stored in the parameter table 270. Herein, the arbitration parameter indicates parameters used for determining the priority of a plurality of bus masters, for example, priority values of each bus masters, bus occupancy allowable amount, and the like.

When the updated arbitration parameters are stored in the parameter table 270, the permission decision unit 240 reads these arbitration parameters from the parameter table 270. [ Then, the permission decision unit 240 decides whether to transmit a bus request permission signal preferentially to a bus request signal from a bus master by using the read arbitration parameter. That is, the grant decision unit 240 grants access to the bus 230 according to the priorities of the first to third bus masters 212, 214, and 216 based on the arbitration parameters in the parameter table 270. In the embodiment shown in FIG. 2, the parameter update unit 280 is shown included in the bus arbiter 250. However, the present invention is not limited to this, and the parameter update unit 280 may be mounted separately from the bus arbiter 250.

The operation of the bus arbiter 250 will be described in detail as follows.

First, the first to third bus masters 212, 214, and 216 have a plurality of arbitration levels. Arbitration at the highest level is the highest priority, and subsequent level intervention is done. That is, there is a priority between arbitration levels. There are various ways to arbitrate bus masters belonging to the same arbitration level, and these arbitration algorithms are stored in the arbitration policy decision unit 260. [

The bus arbiter 250 according to an embodiment of the present invention preferably adopts a time division multiplexing (TDM) scheme. To accommodate time division multiplexing at the same arbitration level, the occupancy tolerance of each of the bus masters belonging to the same arbitration level is parameterized. Then, the bus master can occupy the bus 230 by the assigned allowable amount.

By the way, during the operation of the SOC bus system 200, the operation status of each bus master is changed in real time. In addition, there is a case where the operating state of the SOC bus system 200 can not be adaptively compensated using the parameters stored in the parameter table 270. [ To cope with this situation, the bus arbitrator 250 according to the present invention can update the arbitration parameters in real time.

That is, the bus monitoring unit 220 monitors the bandwidth request amount and the latency of each of the first to third bus masters 212, 214, and 216 in real time, and outputs a monitoring signal. The monitoring signal output from the bus monitoring unit 220 is transmitted to the parameter updating unit 280. Then, the parameter updating unit 280 reads the bandwidth request amount and the latency information from the received monitoring signal. Then, the parameter update unit 280 determines whether the arbitration parameter in the parameter table 270 is suitable for the current operation state of the SOC bus system 200 using the read bandwidth request amount and latency information, and accordingly updates the arbitration parameter do. The operation in which the parameter update unit 280 updates the arbitration parameter will be described later in detail with reference to FIG.

Since the bus monitoring unit 220 monitors the operation statuses of the first to third bus masters 212, 214, and 216 in real time, the parameter updating unit 280 can also update the arbitration parameters in real time. The arbitration parameter updated in real time is used in the process of determining which bus master the bus grant request decision unit 240 is to grant the bus request.

Therefore, according to the present invention, the arbitration efficiency of the bus arbiter 250 can be maximized while adaptively updating the arbitration parameters of the bus arbiter 250 according to the operation state of the SOC bus system 200.

3 is a flowchart showing a bus arbitration method according to another aspect of the present invention.

First, priority determination information according to the operation status of bus masters is monitored (S310). The priority determination information indicates the bandwidth requirement and latency of each bus master as described above. The monitored prioritization information is used to determine an arbitration policy or to prioritize.

Then, the parameter update unit (see 280 in FIG. 2) receives this priority determination information from the bus monitoring unit (see 220 in FIG. 2), and determines whether the current arbitration parameter value is appropriate based on this priority determination information . The arbitration parameters can be stored in the parameter table (see 270 in FIG. 2) as described above. If the current arbitration parameter value is not appropriate, the currently stored arbitration parameter is updated using the received prioritization information (S330).

In addition, the updated arbitration parameters are stored in the parameter table (see 270 in FIG. 2) and used to determine the priority of the bus masters (S350).

When the arbitration operation at the current time is completed, it is determined whether there is a bus request signal that has not yet been processed (S370). If the bus masters that are to be accessed by the bus are no longer present, i.e. the unprocessed bus request signal is no longer present, the arbitration operation is terminated. However, if there is an unprocessed bus request signal, the process returns to step S310 to monitor the priority information of the bus masters again.

4 is a flowchart showing in detail the arbitration parameter update step (S330) shown in FIG.

First, it is determined whether the latency is more important or the bandwidth requirement is more important among the priority determination information used for arbitrating bus masters (S410). In the bus arbitration method according to another aspect of the present invention, what is more important information among the prioritization information is to actively perform the bus arbitration operation considering the operating environment of various SOC bus systems.

If it is determined that the latency required to process each bus request signal is more important than the bandwidth request amount, it is determined whether the monitored latency value exceeds a preset limit value (S420). If it is determined that the monitored latency value is equal to or greater than a predetermined value, it is regarded as an important situation and the arbitration parameter of the corresponding bus master is increased (S430). Increasing the arbitration parameter correspondingly indicates that the arbitration level of the bus master is raised by one level. That is, when the latency value is equal to or greater than a predetermined value, the arbitration level of the corresponding bus master is increased by one level. Since the arbitration method of the bus arbiter is a method in which inter-level arbitration is a priority method, when the arbitration level of any bus master is raised by one level, the latency value of the corresponding bus master is immediately improved. If the monitored latency value is below the threshold, there will be no change in the arbitration level of the bus master. However, if the monitored latency value is smaller than the predetermined minimum value, the arbitration level of the corresponding master is lowered by one step (S440).

Now, a case will be described in which it is determined that the bandwidth request amount of the bus master is more important than the latency required to process each bus request signal.

First, the bandwidth requirement of the monitored bus master is compared with the occupancy allowable amount actually set by the arbiter (S450). That is, the allowable occupancy amount of the bus master set at the beginning is continuously updated in accordance with the occupation requirement amount of the master that is monitored in real time.

In step 2 above, the set occupancy allowance is updated according to the monitored occupancy requirement as follows.

If the occupancy requirement of the bus master is greater than the bus occupancy allowance, the occupancy allowance is increased (S460). If the occupancy requirement is greater than the occupancy allowance, then the occupancy allowance is increased if there is an unoccupied time slot at the arbitration level or if it is necessary to reduce the occupancy allowance of the other masters (because the monitored occupancy requirement is small) . If the occupancy allowable amount is increased but there is no free time slot and it can not be increased, the latency value will naturally increase accordingly. Although the latency value is not a very important bus master, the increased latency value due to insufficient occupancy tolerance can affect the parameter update. In this case, the latency value is not an individual latency value for each bus request signal, but an average latency value for all bus request signals within a predetermined interval is used. When this average latency value is above the threshold, the master's arbitration level is raised one step. Of course, if you have an opportunity to increase your occupancy before that, you should first increase your occupancy.

Conversely, if the occupancy requirement monitored is less than the bus occupancy allowance of the master, the allowable occupancy amount is reduced (S470). If there is another master that wants to increase the occupancy requirement at the same arbitration level, the corresponding time slot is passed to the corresponding bus master, otherwise, the corresponding time slot is made into an empty slot. If the monitored occupancy requirement is small and the allowable occupancy is reduced, and the allowable amount becomes less than the preset minimum value, the arbitration level is lowered by one level. In this way, the arbitration parameter of the corresponding bus master is adjusted (S480) according to the occupancy tolerance and the magnitude of the monitored occupancy requirement, and the adjusted arbitration parameter is used to determine the occupancy level of the corresponding bus master.

If it is determined that there is an unprocessed bus master (S490), it is determined whether more important information among the priority determination information (S410) Lt; / RTI >

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.

Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

According to the present invention, as compared with the conventional method in which the parameter values necessary for bus arbitration such as the arbitration priority and the bus occupation allowable amount are fixed, the parameter values are automatically updated with the parameter values most suitable for the bus situation at that time through real- Performance is improved.

Further, according to the present invention, the bus masters can be arbitrated so that the required latency value for each bus request signal is individually adapted to the bus masters, which are important bus masters and the average bus masters.

In addition, according to the present invention, it is possible to monitor the bus occupancy rate of the bus masters in real time and reflect the corresponding information at the time of arbitration.

Claims (5)

A bus arbitration apparatus for arbitrating a plurality of bus masters that generate a bus request signal and occupy a bus in response to a bus request permission signal generated in response to the bus request signal, A bus monitoring unit monitoring at least one of a bandwidth requirement and a latency of the bus masters in real time to output a monitoring signal; And Updating the arbitration parameters of the bus masters based on the monitoring signal output from the bus monitoring unit and selectively transmitting the bus request permission signal to the plurality of bus masters according to the updated arbitration parameters and a predetermined arbitration policy Wherein the bus arbiter comprises a bus arbiter. The bus arbiter according to claim 1, A parameter table for storing arbitration parameters; A parameter updating unit for updating the arbitration parameter based on the monitoring signal received from the bus monitoring unit; An arbitration policy decision unit for determining an arbitration policy to be applied to the arbitration parameter; And And a permission decision unit for generating the bus request permission signal based on the arbitration policy received from the arbitration policy decision unit and the arbitration parameter stored in the parameter table. A bus arbitration method for arbitrating bus masters of a plurality of bus masters that generate a bus request signal and occupy a bus in response to a bus request permission signal generated in response to the bus request signal, Monitoring in real time the priority determination information for determining the priority of the bus masters; An updating step of updating an arbitration parameter in real time based on the monitored priority information; And And arbitrating the bus occupancy of the plurality of bus masters by selectively transmitting the bus request grant signal to the plurality of bus masters according to the updated arbitration parameter and a predetermined arbitration policy. Intervention method. 4. The method according to claim 3, Wherein the bus master is at least one of a bandwidth requirement and a latency of the bus masters. 5. The method of claim 4, wherein the priority determination information includes a bandwidth request amount and the latency of the bus masters, Wherein, Selecting more important priority information among the bandwidth requirement and the latency; Comparing the selected priority determination information with a predetermined value or more; And updating the arbitration parameter based on the comparison result.

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