JPH10222462A - Mediation device - Google Patents

Abstract

(57) Abstract: The present invention relates to an event (for example, a right to use a bus or acceptance of an interrupt) that can be occupied by only one entity (for example, one device) at a time. An occupation request (for example, a bus use request or an interrupt request) from each of a plurality of entities (for example, a plurality of devices) is received, and one of the entities requesting occupation is permitted to occupy the event. With regard to the arbitration device to be given, a relatively small-scale circuit configuration is used to efficiently determine an entity to which permission to occupy an event from among a large number of entities. A plurality of subjects are grouped, and priority is sequentially given to any one group (subject group) by a round robin method, and among the groups to which the priority is given, the priority is sequentially assigned. The subject to be occupied is determined by the fixed priority method to which rotation is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of events relating to one event (for example, a right to use a bus or acceptance of an interrupt) which can be occupied by only one entity (for example, one device) at the same time. An arbitration that receives an occupation request (for example, a bus use request or an interrupt request) from each of the subjects (for example, a plurality of devices), and gives permission to occupy the event to any one of the subjects requesting the occupation. Related to the device.

[0002]

2. Description of the Related Art As a method of arbitrating a bus use request of each device and a request such as an interrupt from each device, a fixed priority determination method in which priorities are fixed in advance,
There is known a round robin priority determination method for inquiring each device cyclically about the presence or absence of a request.

[0003] These methods are widely and generally used, and the former fixed priority determination method has a higher priority for devices or the like that use resources most frequently in the system in order to keep the priority fixed. By allocating the order, efficient operation of the system is possible.
In the case of the latter round robin priority determination method,
Applies to applications that want to have fair priorities. Since both methods are described in detail in "VME Bus Architecture Manual" (CQ Publishing Co., Ltd.) and the like, detailed description thereof is omitted here.

[0004]

As a problem of the prior art described above, in the former fixed priority determination method, when the number of devices having the request right is small, the realized circuit scale does not matter. There is a problem that the circuit for realization increases exponentially as the number increases.

[0005] When the latter round robin method is adopted, particularly when there are a large number of devices having a request right, in some cases, a service interval for receiving a request is widened, and a buffer for each device must be prepared. The capacity increases. In addition, since request reception is performed in a polling format, if there is no request from the device during the time period in which the request is received, the scheduler that arbitrates the request has to insert idle (wasteful) time. And efficient use of resources becomes impossible.

In order to eliminate the idle time, the former fixed priority determination method is improved, and a method of rotating the priority at the timing of receiving a request from a device is considered. Also, the fixed priority determination circuit becomes enormous as the number of devices having the request right increases.

In view of the above circumstances, the present invention provides an arbitration device that has a relatively small circuit configuration, can receive occupation requests from many clients (subjects), and can efficiently grant occupancy. The purpose is to:

[0008]

The arbitration apparatus of the present invention that achieves the above object receives an occupation request from each of a plurality of subjects regarding one event that can be occupied by only one subject at a time. An arbitration device for granting any one of the entities requesting occupation the occupation permission of the event, wherein the arbitration device requests the occupancy of the event from a plurality of entities having a right to request the occupation of the event. The presence / absence information is input, and for each subject group obtained by dividing the plurality of subjects into a plurality of groups, a request for occupancy of the event from the plurality of subjects constituting one subject group in a predetermined order. Round robin arbitration means for outputting presence / absence information, and a plurality of fixed-priority ports to which information on the presence / absence of the above-mentioned event occupation request from a plurality of entities constituting one entity group is input. Has the door, in accordance with the fixed priority, one of the principal that is requesting the occupancy 1
Priority arbitration means for giving permission to occupy the event to one subject, the round-robin arbitration means, and a plurality of components constituting one subject group which are interposed between the priority arbitration means and output from the round-robin arbitration means. And distributing means for inputting information on the presence or absence of an occupation request from the subject to the plurality of ports while sequentially switching the correspondence between the plurality of subjects and the plurality of ports.

In the arbitration device of the present invention, a plurality of subjects are grouped, and first, any one group (subject group) is given priority in a round robin manner. One subject group includes a plurality of subjects. Therefore, compared to a case where one subject is given priority, any subject in the subject group that has obtained priority has not requested occupation and has no idle status. The possibility of wasting (wasted) time is greatly reduced. Among the groups to which the priority is given, the subject to be occupied is determined by the fixed priority method to which the priority is added.
The number of subjects in one subject group can be suppressed to a certain small number, and the circuit scale can be small. Therefore, according to the arbitration device of the present invention, efficient arbitration can be performed with a relatively small circuit configuration.

Here, in the arbitration device of the present invention,
A memory in which schedule information indicating the order of the subject group is stored, wherein the round robin arbitration unit is arranged in an order according to the schedule information stored in the memory;
It is preferable to sequentially output information on the presence / absence of an occupation request for the event from a plurality of subjects constituting each subject group, for each subject group.

In this case, the memory may store schedule information that allows one subject group to be arranged in a plurality of order positions while making a round of the plurality of subject groups. preferable. When the arbitrating device of the present invention includes a memory in which the above schedule information is stored, priority can be given to each group (each subject group) in an arbitrary order, and one priority can be given during one round of the plurality of subject groups. In the case of schedule information in which the subject groups are allowed to be arranged in a plurality of order positions, a larger number of access rights (priority of occupation) can be given to a subject group having a certain characteristic as compared with another subject group. . If a rewritable memory is used as this memory, it is possible to change the order and frequency of giving the occupation priority to each subject group at that time.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a configuration block diagram of an arbitration device according to an embodiment of the present invention. The arbitration device shown in FIG. 1 includes a schedule state machine 10, a 6-bit counter 1
1, RAM 12 for storing schedule information table 12a, 2-bit counter 13, first selector 14, first distributor 15, fixed priority determination circuit 1
6, a second distributor 17, and a second selector 18.

Here, it is assumed that a total of 40 devices (not shown) are grouped into a total of 10 groups each including 4 devices, and requests Req ( 0
0:03), Req (10:13), ..., Req (9
0:93) and give priority to any one device. Here, Req (ij: ik)
, K represent group numbers, and j,..., K represent group numbers. For example, Req (00:03) represents request signals of four devices 0 to 3 in group 0.

The schedule state machine 10 outputs a count-up enable to the 6-bit counter 11 at a timing synchronized with the clock CLK.
In response to reaching the end (end) of the schedule information table 12a stored in the AM 12, the 6-bit counter 11 is cleared, and a counter-up enable is output to the 2-bit counter 13.

FIG. 2 is a diagram showing an example of the schedule information table stored in the RAM 12. A group number and an end flag are stored for each address. Here, the end flag is indicated by negative logic, indicating that the end flag “L” is the last address of the schedule information table.

FIG. 3 shows a schedule state machine 1
It is a state transition diagram of 0. For example, when the power is turned on, the 6-bit counter is cleared at a predetermined reset timing (state S0), a count-up enable is output to the 6-bit counter 11, and the state shifts to state S1. 6-bit counter 11
Is incremented each time the clock CLK is input, the count value of the 6-bit counter 11 is input to the RAM 12 as an address, and the group number and end flag are obtained from the corresponding address of the schedule information table 12a stored in the RAM 12. Is read. The read group number is input to the first and second selectors 14 and 18 as schedule information. This schedule information will be described later. The end flag read from the RAM 12 is input to the schedule state machine 10, and the schedule state machine maintains the state S1 shown in FIG. 3 while the end flag is at "H", and the end flag is set to "L". ", The state transits to the state S0, the 6-bit counter is cleared, the count value of the 6-bit counter 11 is returned to the head address of the schedule information table 12a, and the 2-bit counter 13 The counter 12 outputs the count-up enable signal only while the counter 12 counts up by one. The 2-bit counter 12 is configured so that the count value cyclically changes as 0 → 1 → 2 → 3 → 0 → 1 →... Every time it counts up. The count value of the 2-bit counter 13 is input to the first and second distributors 15 and 17.

In the schedule state machine 10,
Returning to the state S0 shown in FIG. 3, the 6-bit counter 11 is cleared, and the count-up enable is output to the 2-bit counter 13, the state immediately transits to the state S1, and thereafter, this operation is repeated. The schedule information indicating the group number read from the RAM 12 is input to the first and second selectors 14 and 18 as described above.

In response to the schedule information, the first selector 14 selectively passes requests from four devices constituting a group represented by the schedule information and inputs the requests to the first distributor 15. For example, if the schedule information input this time represents the group 0, the schedule information from the four devices constituting the group 0
The request Req (00:03) is sent to the four input terminals IN0, IN1, IN2, IN3 of the first distributor 15.
Respectively. The same applies to the case where the schedule information input to the first selector 14 represents groups 1 to 9 other than group 0.

The second selector 18 has four output terminals OUT0, OUT1, and OUT of the second distributor 17.
2. The signal output from OUT3 is output as an acknowledgment to four devices forming a group represented by the schedule information input this time. That is, for example, the schedule information input to the second selector 18 this time is the group 0
In this case, the signals output from the four output terminals OUT0, OUT1, OUT2, and OUT3 of the second distributor 17 are the acknowledges of the devices 0, 1, 2, and 3 of the group 0, respectively (these signals are the group 0). Acknowledgments to the four devices of Ack (0
0:03)). Acknowledge Ack (10:13)-Ack of other groups 1-9
(90:93) are all held at the “H” level. At this time, the output terminals OUT0, OUT0 of the second distributor 17
1, OUT2 and OUT3 from "L", "H",
Assuming that “H”, “H” is output, the group 0
Will be given priority. The same applies when the schedule information input to the second selector 18 represents groups 1 to 9 other than group 0.

FIG. 4 shows the first and second selectors 14,
FIG. 18 is a diagram showing an example of a transition of a group selected by 18. In the schedule information table shown in FIG. 2, group 0 → group 1 → group 2 → group 0 →... → group 9 are stored in the order of address 0 to address n−2, and address n where group 9 is stored. Since the end flag “L” is stored in −2, the group 9 at the address n−2 returns to the group 0 at the address 0.

FIG. 4 shows the transition of this group. The first and second selectors 14 and 18 sequentially select each group in this order. FIG. 5 to FIG.
FIG. 10 is a diagram showing transition of a connection state between input and output terminals of a second distributor. 5 to 8 show states when the count values of the 2-bit counter 13 shown in FIG. 1 are 0, 1, 2, and 3, respectively. In the first distributor 15, as the count value changes, Four input terminals IN0, IN
The connection state between the four input / output terminals is switched so that the signals input from the input terminals 1, IN2, and IN3 are sequentially switched and output from the four output terminals OUT1, OUT2, and OUT3. Then, the connection state between the four input / output terminals of the second distributor 17 is switched so that the signal order exchanged by the first distributor 15 is restored.

Table 1 is a table showing the relationship between the input of the fixed priority decision circuit 16 and the output.

[0023]

[Table 1]

Here, the logic is indicated by negative logic. If IN0 is "L", OUT0 is "L" and OUT1 is irrespective of whether IN1 to IN3 are "L" or "H".
1 to OUT3 all become "H", and a priority is given to the device that has input the request from IN0.
When IN0 is “H” and IN1 is “L”, OU
When only T1 is "L", IN0 and IN1 are both "H" and IN2 is "L", only OUT2 is "L", and IN0 to IN2 are all "H" and IN
When 3 is "L", only OUT3 is "L". That is, the fixed priority determination circuit 16 shown in FIG.
Has the highest priority, and the priority order is IN1, IN2, IN3.

The arbitration apparatus shown in FIG. 1 is configured as described above. The first selector 14 sequentially gives priority to each group in a round-robin manner according to schedule information, and the priority is given. In the group, the priority is sequentially changed by the first distributor 15 according to the count value of the 2-bit counter 13, and the priority is given to one of the devices by the fixed priority determination circuit 16. The second distributor 17 and the second distributor
Selector 18 plays a role of returning the signal arrangement to the original order.

In the above embodiment, the first selector 1
A group is selected in the round robin method realized by the method No. 4. Since a plurality of devices are included in the selected group, none of the plurality of devices output a request as compared with a case where the round robin method is applied to each device. The possibility, that is, the possibility that the time when the group is selected becomes idle (wasted) time is greatly reduced, and efficient use of resources becomes possible.

In the group selected by the round robin method, the priority of the signal transmission path is changed by the 2-bit counter 13 and the first distributor 15 while the priority is determined by the fixed priority determination circuit 16 in the fixed priority method. The device to which the right is assigned is determined, and the number of devices in one group is determined with a small circuit configuration by forming one group with a small number of devices such as the four devices in the above embodiment. be able to.

That is, in the above-described embodiment, it is possible to realize an arbitration device that has a relatively small-scale circuit configuration as a whole and performs efficient priority assignment with little room for entering idle time. In the above embodiment, the RAM
The schedule information table 12 in 12
a, and the first selector 14 selects a group according to the round robin method in accordance with the schedule information read therefrom. Therefore, the first selector 14 rewrites the schedule information table 12a in the RAM 12 to select a plurality of groups. You can freely change the order of selection,
The number of times each group is selected can be freely determined.

[0029]

As described above, according to the present invention,
With a relatively small-scale circuit configuration, it is possible to efficiently determine a subject to be given permission to occupy an event from a large number of subjects.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment of an arbitration device of the present invention.

FIG. 2 is a diagram showing an example of a schedule information table stored in a RAM.

FIG. 3 is a state transition diagram of a schedule state machine.

FIG. 4 is a diagram illustrating an example of a transition of a group selected by first and second selectors.

FIG. 5 is a diagram showing a connection state between input and output terminals of the first and second distributors.

FIG. 6 is a diagram showing a connection state between input and output terminals of the first and second distributors.

FIG. 7 is a diagram showing a connection state between input and output terminals of the first and second distributors.

FIG. 8 is a diagram showing a connection state between input and output terminals of the first and second distributors.

[Explanation of symbols]

 Reference Signs List 10 schedule state machine 11 6-bit counter 12 RAM 12a schedule information table 13 2-bit counter 14 first selector 15 first distributor 16 fixed priority determination circuit 17 second distributor 18 second selector

Claims (3)

[Claims] An occupation request is received from each of a plurality of subjects for one event that can be occupied by only one subject at a time, and any one of the subjects requesting occupation is received. In an arbitration device that gives permission to occupy the event to a plurality of entities that have a right to request occupation of the event, input information on the presence or absence of an occupancy request for the event, and A round-robin arbitration means for outputting information on presence / absence of a request for occupation of the event from a plurality of subjects constituting one subject group in a predetermined order for each subject group divided into groups; A plurality of ports having fixed priorities to which information on the presence / absence of the occupation request of the event from a plurality of subjects constituting one subject group is input, and occupied according to the fixed priorities. Request Priority arbitration means for granting any one of the subjects the occupation permission of the event, interposed between the round robin arbitration means, and the priority arbitration means, and output from the round robin arbitration means. Distribution means for inputting information on the presence or absence of an occupation request from a plurality of subjects constituting one subject group to the plurality of ports while sequentially switching the correspondence between the plurality of subjects and the plurality of ports. An arbitration device comprising: 2. A memory for storing schedule information indicating an order of the subject groups, wherein the round-robin arbitration means sequentially performs a process for each subject group in an order according to the schedule information stored in the memory. 2. The arbitration device according to claim 1, wherein the arbitration device outputs information on whether or not there is a request for occupation of the event from a plurality of subjects constituting each subject group. 3. The memory according to claim 1, wherein the memory stores schedule information that allows one subject group to be arranged in a plurality of order positions while making a round of the plurality of subject groups. The arbitration device according to claim 2.