Abstract:
A bus arbitration apparatus and method are provided. A plurality of masters may be classified into master types based on master characteristics, and bus arbitration may be performed. Thus, it is possible to prevent a bus from being distributed to a predetermined master, and it is possible to improve overall performance of a bus system by solving a problem of unbalanced distribution of performance between the plurality of masters.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2010-0112671, filed on Nov. 12, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One or more embodiments of the following description relate to a bus arbitration apparatus and method, and more particularly, to a bus arbitration apparatus and method based on characteristics of masters. 
     2. Description of the Related Art 
     Recently, as various types of application programs are implemented in a single system, the number of masters forming a system is increasing, and types and characteristics of masters are becoming diverse. Accordingly, a conventional bus arbitration method has been developed by focusing on a best performance shown by each of various masters in a system. 
     However, to improve overall system performance, performance of each master needs to be efficiently adjusted. 
     For example, assuming that four processors and a single shared memory are connected to a single bus system, when a request of a single processor transmitted to a bus is processed preferentially, 100% performance of the processor may be achieved, however, the other three processors may not achieve 100% performance, due to the influence of the preferentially processed processor. In this example, overall system performance may be matched to the three processors, instead of the processor achieving 100% performance. Accordingly, such a bus arbitration scheme may cause an efficiency problem. 
     SUMMARY  
     The foregoing and/or other aspects are achieved by providing a bus arbitration apparatus for arbitrating a plurality of masters sending an arbitration request, the bus arbitration apparatus including a processor to control one or more processor-executable units, a collection unit to collect the arbitration request and accumulated arbitration information for each of the plurality of masters, a Quality of Service (QoS) analyzing unit to classify the plurality of masters into a plurality of master types based on a master characteristic of each of the plurality of masters, and to compute a delay time for each of the plurality of masters based on the accumulated arbitration information, the arbitration request, and the plurality of master types, and an arbitration unit to generate a bus arbitration signal based on the plurality of master types and the delay time, the bus arbitration signal being used to arbitrate the plurality of masters. 
     The foregoing and/or other aspects are achieved by providing a bus arbitration method for arbitrating a plurality of masters sending an arbitration request, the bus arbitration method including collecting the arbitration request and accumulated arbitration information for each of the plurality of masters, classifying the plurality of masters into a plurality of master types based on a master characteristic of each of the plurality of masters, computing, by way of a processor, a delay time for each of the plurality of masters based on the accumulated arbitration information, the arbitration request, and the plurality of master types, and generating a bus arbitration signal based on the plurality of master types and the delay time, the bus arbitration signal being used to arbitrate the plurality of masters. 
     The foregoing and/or other aspects are achieved by providing a bus arbitration apparatus for arbitrating a plurality of masters each sending an arbitration request. The bus arbitration apparatus includes a processor to control one or more processor-executable units, a Quality of Service (QoS) analyzing unit to classify the plurality of masters into a plurality of master types based on a master characteristic of each of the plurality of masters and to compute a delay time for each of the plurality of masters based on arbitration information accumulated for each of the plurality of masters, the arbitration requests, and the plurality of master types, and an arbitration unit to generate a bus arbitration signal to arbitrate the plurality of masters based on the plurality of master types and the delay time. 
     The foregoing and/or other aspects are achieved by providing a bus arbitration method for arbitrating a plurality of masters each sending an arbitration request. The bus arbitration method includes classifying the plurality of masters into a plurality of master types based on a master characteristic of each of the plurality of masters, computing, by way of a processor, a delay time for each of the plurality of masters based on arbitration information accumulated for each of the plurality of masters, the arbitration requests, and the plurality of master types, and generating a bus arbitration signal to arbitrate the plurality of masters based on the plurality of master types and the delay time. 
     Additional aspects, features, and/or advantages of example embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the example embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  illustrates a block diagram of a configuration of a bus arbitration apparatus according to example embodiments; 
         FIG. 2  illustrates a diagram of master types according to example embodiments; 
         FIG. 3  illustrates a graph of a performance of a single transmission real-time master according to example embodiments; 
         FIG. 4  illustrates a graph of a performance of a single transmission non-real-time master according to example embodiments; 
         FIG. 5  illustrates a graph of a performance of a multi-transmission real-time master according to example embodiments; 
         FIG. 6  illustrates a graph of a performance of a multi-transmission non-real-time master according to example embodiments; 
         FIG. 7  illustrates a graph of a time table associated with data transmission of a single transmission master according to example embodiments; 
         FIG. 8  illustrates a graph of a time table associated with data transmission of a multi-transmission master according to example embodiments; and 
         FIG. 9  illustrates a flowchart of a bus arbitration method according to example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Example embodiments are described below to explain the present disclosure by referring to the figures. 
       FIG. 1  illustrates a block diagram of a configuration of a bus arbitration apparatus according to example embodiments. 
     Referring to  FIG. 1 , a bus arbitration apparatus  100  for arbitrating a plurality of masters sending an arbitration request for a bus system may include, for example, a collection unit  110 , a Quality of Service (QoS) analyzing unit  120 , and an arbitration unit  130 . 
     The collection unit  110  may collect the arbitration requests and accumulated arbitration information for each of the plurality of masters. 
     The accumulated arbitration information may include at least one of requested data amount information, transmitted data amount information, remaining data amount information, and current time information. 
     The QoS analyzing unit  120  may classify the plurality of masters into a plurality of master types based on a master characteristic of each of the plurality of masters. 
     The plurality of master types may include a single transmission real-time master, a multi-transmission real-time master, a single transmission non-real-time master, and a multi-transmission non-real-time master. Hereinafter, the plurality of master types will be further described with reference to  FIG. 2 . 
       FIG. 2  illustrates a diagram of master types according to example embodiments. 
     Referring to  FIG. 2 , a master  200  may be divided into a real-time master  211 , and a non-real-time master  212 . 
     The real-time master  211  may be a master for which performance is reduced to “0” when a bus insufficiently supports an amount of data required to be transmitted. 
     The non-real-time master  212  may be a master for which performance is reduced at a predetermined ratio when a data processing time takes longer than a time requirement. 
     The real-time master  211  may be divided into a single transmission real-time master  221 , and a multi-transmission real-time master  222 . 
     Additionally, the non-real-time master  212  may be divided into a single transmission non-real-time master  223 , and a multi-transmission non-real-time master  224 . 
     A single transmission master classified as the single transmission real-time master  221  or the single transmission non-real-time master  223  may be a master for processing data by transmitting the data once. 
     Accordingly, the single transmission real-time master  221  may process data by transmitting the data once, and may have the performance that is reduced to “0” when a bus insufficiently supports an amount of data required to be transmitted. 
     Additionally, the single transmission non-real-time master  223  may process data by transmitting the data once, and may have the performance that is reduced at a predetermined ratio when a data processing time takes longer than a time requirement. 
     A multi-transmission master classified as the multi-transmission real-time master  222  or the multi-transmission non-real-time master  224  may be a master for processing data by transmitting the data multiple times. 
     Accordingly, the multi-transmission real-time master  222  may process data by transmitting the data multiple times, and may have the performance that is reduced to “0” when a bus insufficiently supports an amount of data required to be transmitted. 
     Additionally, the multi-transmission non-real-time master  224  may process data by transmitting the data multiple times, and may have the performance that is reduced at a predetermined ratio when a data processing time takes longer than a time requirement. 
     Since the single transmission real-time master  221 , the multi-transmission real-time master  222 , the single transmission non-real-time master  223 , and the multi-transmission non-real-time master  224  have different characteristics as described above, each performance may be changed in different forms when data processing is delayed. Hereinafter, a change in performance depending on a delay of data processing will be described in detail with reference to  FIGS. 3 to 6 . 
       FIG. 3  illustrates a graph of the performance of a single transmission real-time master according to example embodiments. 
     Referring to the graph  300  of  FIG. 3 , the single transmission real-time master may process data by transmitting the data once, in response to a single arbitration request  310 . Additionally, when a bus insufficiently supports an amount of data required to be transmitted, the performance of the single transmission real-time master may be reduced to “0”, as indicated by reference numeral  320 . 
     The performance of the single transmission real-time master may be computed, as given in Equation 1.
 
Single transmission real-time master=(Delay time&gt;0)0:100  [Equation 1]
 
       FIG. 4  illustrates a graph of the performance of a single transmission non-real-time master according to example embodiments. 
     Referring to the graph  400  of  FIG. 4 , the single transmission non-real-time master may process data by transmitting the data once, in response to a single arbitration request  410 . Additionally, when a data processing time takes longer than a time requirement, the performance of the single transmission non-real-time master may be reduced at a predetermined ratio, as indicated by reference numeral  420 . 
     The performance of the single transmission non-real-time master may be computed, as given in Equation 2.
 
Single transmission non-real-time master=Time requirement/(Time requirement+Delay time)×100  [Equation 2]
 
       FIG. 5  illustrates a graph of the performance of a multi-transmission real-time master according to example embodiments. 
     Referring to the graph  500  of  FIG. 5 , the multi-transmission real-time master may process data by transmitting the data multiple times, in response to a plurality of arbitration requests  511 ,  512 ,  513 ,  514 , and  515 . Additionally, when a bus insufficiently supports an amount of data required to be transmitted, the performance of the multi-transmission real-time master may be reduced to “0”, as indicated by reference numeral  520 . 
     The performance of the multi-transmission real-time master may be computed, as given in Equation 3.
 
Multi-transmission real-time master=(Delay time&gt;0)0:100  [Equation 3]
 
       FIG. 6  illustrates a graph of the performance of a multi-transmission non-real-time master according to example embodiments. 
     Referring to the graph  600  of  FIG. 6 , the multi-transmission non-real-time master may process data by transmitting the data multiple times, in response to a plurality of arbitration requests  611 ,  612 ,  613 ,  614 , and  615 . Additionally, when a data processing time takes longer than a time requirement, the performance of the multi-transmission non-real-time master may be reduced at a predetermined ratio, as indicated by reference numeral  620 . 
     The performance of the multi-transmission non-real-time master may be computed, as given in Equation 4.
 
Multi-transmission non-real-time master=Time requirement/(Time requirement+Delay time)×100  [Equation 4]
 
     Referring back to  FIG. 1 , the QoS analyzing unit  120  may compute a delay time for each of the plurality of masters, based on the accumulated arbitration information, the arbitration requests, and the plurality of master types. 
     According to an aspect, the QoS analyzing unit  120  may compute a delay time of a single transmission master, based on at least one of delay time restriction condition information, data margin information, transmitted data amount information, requested data amount information, remaining data amount information, and current time information with respect to the single transmission master. Here, the single transmission master may be classified as the single transmission real-time master or the single transmission non-real-time master. 
     Additionally, the QoS analyzing unit  120  may compute a delay time of a multi-transmission master, based on at least one of data period information, information on an amount of data transmitted per period, data margin information, transmitted data amount information, remaining data amount information, and current time information with respect to the multi-transmission master. Here, the multi-transmission master may be classified as the multi-transmission real-time master or the multi-transmission non-real-time master. 
     Hereinafter, a method of computing a delay time will be further described with reference to  FIGS. 7 and 8 . 
       FIG. 7  illustrates a graph  700  of a time table associated with data transmission of a single transmission master according to example embodiments. 
     A bus arbitration apparatus according to example embodiment may compute a delay time of the single transmission master, based on information set in advance in a bus system, and accumulated arbitration information regarding the single transmission master. Here, the single transmission master may be classified as the single transmission real-time master or the single transmission non-real-time master. 
     The information set in advance in the bus system may include information regarding a delay time restriction condition and a data margin  740 . 
     Additionally, the accumulated arbitration information regarding the single transmission master may include information regarding a requested data amount  710 , a transmitted data amount  720 , a remaining data amount  730 , and a current time. 
     According to an aspect, the bus arbitration apparatus may compute the delay time of the single transmission master, using Equation 5.
 
Delay time of single transmission master=(Current time+Remaining data amount+Data margin)−Time requirement  [Equation 5]
 
     Here, the current time may indicate a cycle counted from a time point that an arbitration request  760  is received from the single transmission master. 
     The remaining data amount  730  may indicate a data amount obtained by subtracting the transmitted data amount  720  from the requested data amount  710 . 
     The requested data amount  710  may indicate a number of pieces of data requested in response to the arbitration request  760  from the single transmission master. 
     The transmitted data amount  720  may indicate a number of pieces of data transmitted from the time point that the arbitration request  760  is received from the single transmission master up to the current time. 
     The data margin  740  may indicate a number of cycles sufficient to satisfy a time requirement  750  for the single transmission master. 
     The time requirement  750  may indicate a value obtained by adding the requested data amount  710  and the delay time restriction condition, and may be computed using Equation 6.
 
Time requirement=Requested data amount+Delay time restriction condition  [Equation 6]
 
     Here, the delay time restriction condition may indicate a time obtained by excluding a data transmission cycle from an allowable delay time of the single transmission master. 
       FIG. 8  illustrates a graph of a time table associated with data transmission of a multi-transmission master according to example embodiments. 
     A bus arbitration apparatus according to example embodiment may compute a delay time of the multi-transmission master, based on information set in advance in a bus system, and accumulated arbitration information regarding the multi-transmission master. Here, the multi-transmission master may be classified as the multi-transmission real-time master or the multi-transmission non-real-time master. 
     The information set in advance in the bus system may include information regarding a data period, an amount  810  of data transmitted per period, and a data margin  840 . 
     Additionally, the accumulated arbitration information regarding the multi-transmission master may include information regarding a requested data amount  810 , a transmitted data amount  820 , a remaining data amount  830 , and a current time. 
     According to an aspect, the bus arbitration apparatus may compute the delay time of the multi-transmission master, using Equation 7.
 
Delay time of multi-transmission master=(Current time+Remaining data amount+Data margin)−Time requirement  [Equation 7]
 
     Here, the current time may indicate a cycle counted from an initiation of a data period. 
     The data period may indicate a time interval for data transmission. 
     The remaining data amount  830  may indicate a data amount obtained by subtracting the transmitted data amount  820  from the amount  810  of data transmitted per period. 
     The amount  810  of data transmitted per period may indicate an amount of data that needs to be transmitted during a single data period. 
     The transmitted data amount  820  may indicate a number of pieces of data transmitted to a current cycle from the initiation of the data period. 
     The data margin  840  may indicate a number of cycles sufficient to satisfy a time requirement  850  for the multi-transmission master. 
     The time requirement  850  may indicate a data period, and may be computed using Equation 8:
 
Time requirement=Data period  [Equation 8]
 
     Referring back to  FIG. 1 , the arbitration unit  130  may generate a bus arbitration signal based on the plurality of master types and the delay time. The bus arbitration signal may be used to arbitrate the plurality of masters. 
     According to an aspect, the arbitration unit  130  may group the plurality of masters into a plurality of groups based on the plurality of master types and the delay time. 
     The arbitration unit  130  may generate a group arbitration signal for each of the plurality of groups. The group arbitration signal may be used to arbitrate at least one master included in a single group. Depending on example embodiments, different bus arbitration methods may be set for each of the plurality of groups, and a group arbitration signal may be generated for each of the plurality of groups based on the set bus arbitration methods. 
     The arbitration unit  130  may generate a bus arbitration signal from the group arbitration signal, based on priority information of the plurality of groups. 
     According to an aspect, the arbitration unit  130  may group, in a first group, a master that has a delay time exceeding “0” and that is classified as a single transmission real-time master and a master that has a delay time exceeding “0” and that is classified as a multi-transmission real-time master among the plurality of masters. 
     Additionally, the arbitration unit  130  may group, in a second group, a master that has a delay time exceeding “0” and that is classified as a multi-transmission non-real-time master among the plurality of masters, and a master classified as a single transmission non-real-time master among the plurality of masters. 
     The arbitration unit  130  may also group, in a third group, a master that has a delay time of “0” and that is classified as a multi-transmission non-real-time master among the plurality of masters. 
     The arbitration unit  130  may also group, in a fourth group, a master that has a delay time of “0” and that is classified as a single transmission real-time master, and a master that has a delay time of “0” and that is classified as a multi-transmission real-time master among the plurality of masters. 
     Depending on example embodiments, the priority information may be set so that priority levels may be assigned to the first group to the fourth group in a descending order. In other words, the first group may have a highest priority level, and the fourth group may have a lowest priority level. 
     The arbitration unit  130  may generate four group arbitration signals for the first group to the fourth group. 
     Additionally, the arbitration unit  130  may generate a final bus arbitration signal from the four group arbitration signals, based on the priority information. 
       FIG. 9  illustrates a flowchart of a bus arbitration method according to example embodiments. 
     The bus arbitration method of  FIG. 9  may be performed to arbitrate a plurality of masters sending an arbitration request to a bus system. In  FIG. 9 , in operation  910 , accumulated arbitration information and an arbitration request for each of the plurality of masters may be collected. 
     The accumulated arbitration information may include at least one of requested data amount information, transmitted data amount information, remaining data amount information, and current time information. 
     In operation  920 , the plurality of masters may be classified into a plurality of master types, based on a master characteristic of each of the plurality of masters. 
     The plurality of master types may include a single transmission real-time master, a multi-transmission real-time master, a single transmission non-real-time master, and a multi-transmission non-real-time master. 
     In operation  930 , a delay time may be computed for each of the plurality of masters, based on the accumulated arbitration information, the arbitration request, and the plurality of master types. 
     According to an aspect, in the bus arbitration method, a delay time of a single transmission master may be computed, based on at least one of delay time restriction condition information, data margin information, transmitted data amount information, requested data amount information, remaining data amount information, and current time information with respect to the single transmission master. Here, the single transmission master may be classified as the single transmission real-time master or the single transmission non-real-time master. 
     Additionally, a delay time of a multi-transmission master may be computed, based on at least one of data period information, information on an amount of data transmitted per period, data margin information, transmitted data amount information, remaining data amount information, and current time information with respect to the multi-transmission master. Here, the multi-transmission master may be classified as the multi-transmission real-time master or the multi-transmission non-real-time master. 
     In operation  940 , a bus arbitration signal may be generated based on the plurality of master types and the delay time. Here, the bus arbitration signal may be used to arbitrate the plurality of masters. 
     According to an aspect, in operation  940 , the plurality of masters may be grouped into a plurality of groups based on the plurality of master types and the delay time. 
     Additionally, in operation  940 , a group arbitration signal for each of the plurality of groups may be generated. The group arbitration signal may be used to arbitrate at least one master included in a single group. Depending on example embodiments, different bus arbitration methods may be set for each of the plurality of groups, and a group arbitration signal may be generated for each of the plurality of groups based on the set bus arbitration methods. 
     Furthermore, in operation  940 , a bus arbitration signal may be generated from the group arbitration signal, based on priority information of the plurality of groups. 
     According to an aspect, a master that has a delay time exceeding “0” and that is classified as a single transmission real-time master or a multi-transmission real-time master among the plurality of masters may be grouped in a first group. 
     Additionally, a master that has a delay time exceeding “0” and that is classified as a multi-transmission non-real-time master among the plurality of masters, and a master classified as a single transmission non-real-time master among the plurality of masters may be grouped in a second group. 
     Furthermore, a master that has a delay time of “0” and that is classified as a multi-transmission non-real-time master among the plurality of masters may be grouped in a third group. 
     Moreover, a master that has a delay time of “0” and that is classified as a single transmission real-time master or a multi-transmission real-time master among the plurality of masters may be grouped in a fourth group. 
     Depending on example embodiments, the priority information may be set so that priority levels may be assigned to the first group to the fourth group in a descending order. In other words, the first group may have a highest priority level, and the fourth group may have a lowest priority level. 
     In the bus arbitration method, four group arbitration signals for the first group to the fourth group may be generated. 
     Additionally, a final bus arbitration signal may be generated from the four group arbitration signals, based on the priority information. 
     The above-described example embodiments may be recorded in non-transitory computer-readable media including program instructions to implement various operations embodied by a computer. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the example embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of non-transitory computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVDs; magneto-optical media such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. 
     Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described example embodiments, or vice versa. Any one or more of the software modules or units described herein may be executed by a dedicated processor unique to that unit or by a processor common to one or more of the modules. The described methods may be executed on a general purpose computer or processor or may be executed on a particular machine such as the bus arbitration apparatuses described herein. 
     Although example embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these example embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.