JP3039451B2 - Priority arbitration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arbitration device, and more particularly to a priority arbitration device in a communication line transfer processing device.

[0002]

2. Description of the Related Art Hitherto, an arbitration circuit of this kind has been used in a communication system for the purpose of providing a reliable transfer service for communication and an appropriate response.

For example, Japanese Patent Laid-Open Publication No. Hei 5-61818 discloses a means for counting the number of times a request signal is output from a requesting device, for each requesting device. A technique is described in which a request is received in a priority order when a request signal is output from a requesting device, and the priority of request reception is changed according to the request frequency of each requesting device. Also, Japanese Patent Application Laid-Open No. 7-139
In Japanese Patent Application Publication No. 25-255, at least two flip-flop circuits to which clocks having different periods are input are provided as a circuit for generating a bus acquisition signal, and the output of the flip-flop circuit is connected to another flip-flop circuit via an AND gate. A technique is described in which the bus acquisition priority is changed in a time-division manner by connecting to a data input terminal of the data input terminal.

[0004]

The first problem is that an apparatus for accommodating a line having a transfer characteristic whose transfer efficiency varies in a variety of ways on the time axis secures both a high-speed response and an optimum transfer efficiency. It is difficult to do. The reason is that the fixed priority or the rotation priority is determined by the port connected to the arbitration circuit itself, and the priority cannot be followed according to the data transfer mode that fluctuates on the time axis. This is because the control information of the transfer packet itself is not recognized.

[0005] The second problem is that in a system in which priority is fixed with respect to request arbitration, responsiveness of a device assigned to a lower rank becomes extremely poor. Since the priority is fixedly determined by the connection port, it cannot be applied to arbitration of three or more devices. The reason is high priority 2
When a high load is applied to one of the devices, a conflict between mediation rights occurs between the two devices. In the meantime, even if an arbitration request from a lower-priority device comes up, the device falls into an unacceptable state.

A third problem is that, in the method of equalizing the opportunity to circulate the request priority every time arbitration, the speed is reduced as the number of connected devices increases. It cannot be applied to arbitration of many devices having different transfer speeds. The reason is that in a transfer mode in which data transfer is concentrated in a short period of time such as a burst, the priority changes with each transfer, so the fastest continuous transfer must be performed, but during that time the priority is changed by circulation. This is because the transfer of a plurality of other devices having a higher speed intervenes, and the original high speed cannot be maintained.

A fourth problem is that, in a dynamic system in which a device having a large number of requested accesses has a higher priority, a device having a small number of accesses has a low priority, and the responsiveness is deteriorated. Although the number of accesses is small, it cannot be applied to arbitration of devices that require responsiveness. The reason is that although the number of ordinary accesses is small, even if a request for a high-speed response occurs, the arbitration right is not circulated because the arbitration right is used for the higher-ranking device having a large number of accesses. . This is because the priority cannot be changed unless the number of accesses reaches a certain actual number.

A fifth problem is that in the method in which clocks having different phases and different periods are used for the arbitration circuit to change the priority in a time-division manner, the responsiveness of a device connected to an arbitration unit having a slower clock is reduced. It is going to get worse. The reason is that many high priorities are concentrated on the requesting device connected to the arbitration unit having the clock with the highest frequency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a priority arbitration device which improves the response speed and the transfer efficiency.

It is another object of the present invention to provide a priority arbitration device that recognizes control information of a transfer packet flowing through a line and performs high-speed dynamic priority processing.

[0011]

The priority arbitration apparatus of the present invention is provided for each line, and when a packet is received from a corresponding line, a priority code component is extracted from the packet and converted as a priority code signal. When a request for permitting packet data transfer is output and a request permission signal is received, a request processing circuit for stopping the permission request and a priority code signal from the corresponding request processing circuit are provided for each request processing circuit. A priority analysis circuit that, when received, outputs a priority signal of the priority indicated by the priority code signal, and when receiving a request permission signal, outputs a request permission signal to a corresponding request processing circuit; Dynamic priority reconfiguration that accommodates priority signals from the circuit, separates them by priority, then performs priority arbitration processing, and returns a request permission signal to the corresponding priority analysis circuit An arbitration circuit, the respective request processing circuit
Monitors permission requests from
If there is a request source that is not sent even after a long time, the request source
Priority is higher than other request sources, and the dynamic priority
Makes an arbitration request to the configuration / arbitration circuit, and responds to the arbitration request.
Request permission from the dynamic priority reconfiguration / arbitration circuit
If it is returned, send it to the request processing circuit of the request source.
Has a long-term reserved use monitoring circuit, dynamic priority reconfiguration and arbitration
The circuit accommodates priority signals from each of the priority analysis circuits
And classify them according to their priority.
Output the arbitration request signal and receive the request permission signal,
A dynamic controller that outputs a request permission signal to the corresponding request processing circuit
A configuration circuit and a dynamic reconfiguration circuit provided for each priority.
Receiving the priority arbitration request signal of the priority from the
Are output together as an arbitration request signal.
When it is delivered, rotation priority processing is performed and the selected
Output a request permission signal corresponding to the line to the dynamic reconfiguration circuit.
Rotation priority circuits and arbitration request signals from each rotation priority circuit
Group and arbitration request signal group from the long-term on-hold user monitoring circuit
Arbitration request signals from the rotation priority circuit
Arbitration request signal with the highest priority
The corresponding turn the request enable signal corresponding to the arbitration request signal
Output to the rotation priority circuit and an arbitration request signal from the rotation priority circuit
Groups and arbitration request signals from the long-term pending user management circuit
When the two arbitration request signals are the same,
Fixed output of request permission signal corresponding to high arbitration request signal
Including fixed priority arbitration circuit.

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

According to the embodiment of the present invention, the long-term on-hold user monitoring circuit is provided for each request processing line, and becomes a countable state upon receiving a permission request from the request processing circuit. Each time a response confirmation permission signal output together with the output of the request permission signal is received, counting is performed, and when a predetermined value is reached, a counter for outputting a priority arbitration request signal to the fixed priority arbitration circuit, and a counter for each request processing circuit. A gate circuit for returning a request permission signal to a corresponding request processing circuit when the selected request permission signal is output from the fixed priority arbitration circuit while receiving the request permission.

By reading the priority from the control unit of the packet information flowing through the line and making a processing request, the priority is determined based on the packet information without depending on the physical connection port of the line. Arbitration processing can be performed.

Further, by monitoring the long-term hold requester and changing the priority to a higher priority, reliable processing reception and service can be performed.

[0021]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a priority arbitration device according to an embodiment of the present invention.

The priority arbitration device of this embodiment the request processing circuit _{20 1, 20 2, ...,} 20 n and the priority analyzing circuit 30 _1, 3
0 _2, ..., and a 30 _n and the dynamic priority reconfiguration, the arbitration circuit 40 and the long-term hold user monitoring circuit 50.

[0024] The request processing circuit 20 ₁ ~20 _n the line 11 ₁ -
Upon receiving the packet 10 ₁ to 10 _n from 11 _n, from the packet 10 ₁ to 10 _n priority code elements PC _{i (i} = 1~
n) is extracted, and permission of packet data transfer is requested with the bus use request signals 21 _{1 to} 21 _n as the priority code signals 22 _{1 to} 22 _n . The request processing circuit 20 ₁ to 20 _n
When receives a bus request enable signal 51 ₁ to 51 _n from the priority analyzing circuit 30 ₁ to 30 _n bus from the request enable signal 23 ₁ ~ 23 _n or prolonged pending user monitoring circuit 50, the transfer order to your Recognizing that it has been turned around, the priority code signals 22 _{1 to} 22 _{n being} transmitted and the bus use request signal 21 ₁
Stop through 21 _n output enters the forwarding of subsequent packet data.

The priority analysis circuit 30₁~ 30_nIs the request processing times
Road 20₁~ 20_nFrom the bus use request signal 21₁~ 21_nAnd Yu
Previous code signal 22₁~ 22_nIs received, the priority
Signal 22₁~ 22_nAnd analyze the priority signal 31₁~ 3
4₁, 31_Two~ 34_Two, ..., 31_n~ 34_n(Where priority
Degree signal 31₁~ 31_nIs priority 1, priority signal 32₁~ 3
2 _nIs priority 2, priority signal 33₁~ 33_nIs priority 3,
Priority signal 34₁~ 34_nIndicates priority 4, and priority 1 is
Priority code is the highest and priority 4 is the lowest)
Signal 22₁~ 22_nActivate the priority signal with the priority indicated by
To Also, the priority analysis circuit 30₁~ 30_nIs dynamic
The bus use permission signal 35 from the reconfiguration / arbitration circuit 40₁
~ 35_nIs acquired, the request processing circuit 20 of the request source₁~ 2
0_nBus use request permission signal 23₁~ 23_nIs output.

The dynamic priority reconfiguration, the arbitration circuit 40, the priority analyzing circuit 30 ₁ to 30 _n corresponding to each line 11 ₁ to 11 _n
Priority signals 31 ₁ , 32 ₁ , 33 ₁ , 34 ₁ to 34 _{1
1 n, 32 n, 33 n} , 34 n accommodating to a classifying them by priority, then performs the priority arbitration process, priority analysis circuit of the corresponding bus use request permission signal 35 ₁ ~35 _n 30 ₁ ~
30 _n and outputs a response confirmation permission signal 48 to the long-term on-hold user monitoring circuit 50. Also, priority arbitration request signals 41 _{1 to} 41 _n from the long-term on-hold user monitoring circuit 50
Are received, the priority signals 31 ₁ , 32 ₁ , 3
_{3 1, 34 1 ~31 n,} 32 n, 33 n, 34 n higher priority arbiter than the priority indicated by the is performed, the arbitration permission acknowledge signal _{42 1, 42 2, ...,} 42 n , respectively Is returned to the long-term on-hold user monitoring circuit 50 in accordance with the priority arbitration process.

The long-pending user monitoring circuit 50 a bus request signal 21 ₁ through 21 _n from the request processing circuits 20 ₁ to 20 _n
When the bus use request signals 21 _{1 to} 21 _n exceed a certain period (arbitration suspension count), the higher priority arbitration requests are dynamically changed by the corresponding priority arbitration request signals 41 _{1 to} 41 _n . The priority is output to the priority reconfiguration / arbitration circuit 40, and the dynamic priority reconfiguration / arbitration circuit 40 outputs the arbitration permission response confirmation signal 42 ₁ to
Upon acquiring the 42 _n, the corresponding request processing circuit 20 ₁ to 20
returns a bus request enable signal 51 ₁ to 51 _n corresponding to the _n. The number of arbitration reservations in the long-term reservation user monitoring circuit 50 is counted based on the response confirmation permission signal 48 output from the dynamic priority reconfiguration / arbitration circuit 40.

FIG. 2 shows a dynamic priority reconfiguration / arbitration circuit 40.
FIG. 3 is a block diagram illustrating a configuration example of FIG. Dynamic priority reconfiguration
The arbitration circuit 40 includes a dynamic reconfiguration circuit 70 and a rotation priority circuit 80.
It is composed of ₁ to 80 ₄ and the fixed priority arbitrating circuit 90.

The dynamically reconfigurable circuit 70, the line 11 ₁ to 1
Priority signals 31 ₁ , 32 ₁ , 33 ₁ , 3 corresponding to 1 _n
4 _1, ..., accommodates a _{31 n, 32 n, 33 n} , 34 n, the priority signal 31 ₁ to 31 _n priority of the highest priority signal 34 ₁ to 34C _n priority is most It is configured to be lower.

The dynamic reconfigurable circuit 70 classifies the priority signals according to the priority, and sets the priority signals 31 _{1 to} 31 _n as the priority ₁ group and the priority signals 32 ₁ as the priority 2 group. the to 32 _n, the priority signal 33 ₁ ~ 33 _n as a group of priority 3, and outputs the priority signal 34 ₁ to 34C _n as a group of priority 4. Also, request permission signals 35 _{11 to} 35 _1n as priority group ₁ , request permission signals 35 _{21 to} 35 _2n as priority group 2, and request permission as priority group 3 according to the respective priority signals. signal 35 ₃₁ to 35 _3n, and a request enable signal 35 ₄₁ to 35 _4n as the priority group 4. Upon receiving these requests permission signal, the request processing a bus request enable signal 35 ₁ to 35 _n corresponding to the relevant line circuit 20 21 _to
Output to 0 _n .

The rotation priority circuit 80 _{4-80 1} Each priority signal 34 ₁ for each priority from dynamically reconfigurable circuit 70
_{34 n, 33 1 ~33 n,} 32 1 ~32 n, 31 1 ~31 n summarizing a processing request for each group of each priority receives priority arbitration request signal 36 ₄ to the fixed priority arbitrating circuit 90-36 Output as ₁ . If the fixed priority arbitration circuit 90 a request permission signal 37 _{4-37 1} comes output, rotating priority circuit 80 ₄
80 ₁ performs rotation priority processing (priority order for each end of the transfer process is rotated), and outputs a bus request enable signal 35 _{4-35 1} corresponding to the selected line to the dynamically reconfigurable circuit 70 .

Each of the fixed priority arbitration circuits 90 includes a rotation priority circuit.
80₁~ 80_FourArbitration request signal 36 from₁~ 36_FourWhen
Priority arbitration request signal from long-term on-hold user monitoring circuit 50
41 ₁~ 41_nIs receiving. Normally, the priority arbitration request signal
No.36₁~ 36_FourThe highest priority is selected.
The selected priority arbitration request signal 36₁~ 36_FourCorresponding to
Answer confirmation signal 37₁~ 37_FourCorresponds to the rotation priority circuit 80₁
~ 80_FourOutput to At this time, the response confirmation permission signal 48
Are output together. Priority arbitration request signal 41₁~ 41_n
Is the priority arbitration request signal 36₁~ 36_nSet higher than
The priority arbitration request signal 36₁~ 36_FourAnd priority
Degree arbitration request signal 41₁~ 41_nConflicts, priority
Arbitration request signal 41₁~ 41_nOne of them is priority arbitration
Is selected by Request permission signal 37₁~ 37_FourSelection
The request permission signal corresponding to the selected priority arbitration request signal is
Is output.

FIG. 3 is a block diagram showing an example of the configuration of the long-term reservation user monitoring circuit 50. Long term user monitoring circuit 5
0 indicates AND circuits 110 _{1 to} 110 _n and counters 120 ₁ to
120 _n .

The counter 120 ₁ to 120 _n, the request processing circuit 20 ₁ to 20 bus request signals are pending at _n 21
₁ through 21 _n to receive and be countable state, to perform counting each time it receives an acknowledgment permission signal 48 from the fixed priority arbitrating circuit 90, the count value priority arbitration request signal 41 ₁ and reaches a predetermined value to 41 Outputs _n . AND circuit 110 ₁ to 1
10 _n is a permission response acknowledgment signal 4 selected from the fixed priority arbitration circuit 90 during reception of the bus use request signals 21 _{1 to} 21 _n.
When 2 ₁ through 42 _n comes is output to the corresponding request processing circuit 20 ₁ to 20 _n sends back a bus request enable signal 51 ₁ to 51 _n.

Next, the operation of this embodiment will be described with reference to FIGS.

Line 11₁~ 11_nPacket information 10 from
₁-10_nIs each request processing circuit 20₁~ 20_nHas been received by
You. Each request processing circuit 20₁~ 20_nIs packet information reception
Is detected, the priority component is extracted from the control part in the packet.
Priority code signal 22 extracted from PC₁~ 22_nAlong with
Use request signal 21₁~ 21_nAnd priority analysis circuit 30 ₁~
30_nRequest to transfer packet data to
01). At this time, the long-term on-hold user monitoring circuit 50
Use request signal 21₁~ 21_nIs monitored (step
202).

The priority analysis circuits 30 ₁ to 30 _{n make} a processing request at the priority specified by the priority code signals 22 _{1 to} 22 _n to the dynamic priority reconfiguration / arbitration circuit 40 (step). 203).

Referring to FIG. 4, a plurality of lines (line 11 ₁ here described as line 11 _i) If there is a packet information from the priority analyzing circuit 30 ₁ analyzes the priority code signal 22 ₁ For example, as the priority 3, the priority signal 3
In 3 ₁ performs arbitration request to the dynamic priority reconfiguration, the arbitration circuit 40 (step 203). On the other hand, the priority analysis circuit 30 _i (not shown) corresponding to the line 11 _i outputs a dynamic priority reconfiguration / arbitration circuit as the priority j (j is one of 4, 3, 2, 1). An arbitration request is made to 40. The dynamic priority reconfiguration / arbitration circuit 40 performs grouping and arbitration processing for each priority (Step 204).

The arbitration is performed by the fixed priority arbitration circuit 90 at time t _0. If the priority j is 1, the request permission signal 37 ₁ (see FIG. 2) is selected as the highest priority (see FIG. 2). step 206 to 208), followed by the priority processing in priority 1 in rotation preference circuit 80 ₁ under is carried out in rotary manner (step 209, 210). In this example, line 11
_i is output corresponding bus use permission signal 35 _4i is, the priority analyzing circuit 30 _i to the bus grant signal 35 _i is output.

The priority analysis circuit 30 _i returns a bus use request permission signal 23 _i to the subordinate request processing circuit 20 _i (step 210). The request processing circuit 20 _{i that} has acquired the bus use request permission signal 23 _i outputs the bus use request signal 21 _i being transmitted.
And it withdrew the output of the priority code signal 22 _i at time t _1,
At the same time, the transfer of the packet information from the line 11 _i is started.

[0041] When the transfer is completed, at time t ₂ becomes possible following arbitration process. In this case the requester, the priority arbitration request signal 36 _second pending have priority 2 if the highest, request permission signal 37 ₂ is selected. Subsequently priority processing in the priority 2 in the rotation priority circuit 80 ₂ is performed by rotating manner, to activate a line 11 ₁ corresponding request enable signal 35 _21, the priority analyzing circuit 30 _first bus use permission signal ₃₅₁ to the Output (Step 209). Request permission signal 35 ₁ priority analyzing circuit 30 ₁ which has acquired the, the request processing under circuit 2
0 ₁ to bus request enable signal 23 ₁ to pass (step 21
0).

The withdrawal bus request enable signal 23 ₁ requested processing circuit 20 ₁ which has acquired the the bus request signal 21 ₁ during transmission priority code signal 22 ₁ at time t _3, from line 10 ₁ while releasing The transfer of packet information is started (step 213).

The generated one after another higher order priority after another from the other line, the priority arbitration request signals 36 ₁ in the priority 2 of line 10 ₁ corresponding continues as long-term low, pending requests bus request signal 21 ₁ from the processing circuit 20 ₁ is monitored by the long-term hold user monitoring circuit 50 (step 207).

Each time an arbitration operation is performed, the long-term reservation user monitoring circuit 50 counts the response confirmation permission signal 48 output from the dynamic priority reconfiguration / arbitration circuit 40 by the counters 120 _{1 to} 120 _n . When the count value of the counter 120 ₁ to 120 _n reaches a predetermined value, at priority arbitration request signal 41 ₁ as long held party, requesting arbitration to dynamic priority reconfiguration, the arbitration circuit 40.

If there is a long-term holder (step 207),
Since the request of the long-term holder is higher than the normal requester, the priority arbitration request signal 41 ₁ is selected, and the arbitration permission response confirmation signal 42 ₁ is sent as a response to the long-term hold user monitoring circuit 50.
Distributed to

The long-pending user monitoring circuit 50 which received the arbitration permission acknowledgment signal 42 _1, passes the authorization response confirmation signal 51 ₁ to the request processing circuit 20 ₁ (step 211,21
2). Request processing circuit 20 ₁ which has obtained the authorization response confirmation signal 51 _1, a bus use request signal 21 ₁ in the request, withdraws the priority code signal 22 _i, starts transferring the same time packet information to release (step 213).

In this embodiment, the fixed priority of the connection port
Alternatively, the priority can be dynamically reconfigured for each received packet based on control information in the packet received from the line without depending on the priority attribute of the physical port called rotation priority, so that the priority adapted to the transfer mode can be adjusted. Transfer that enables optimal high-speed response can be performed at a time.

In the fixed priority system, there has been a problem that the response efficiency due to the cyclic waiting is poor in the long-term suspension of the lower order in the fixed priority system, and the response efficiency due to the circulation wait is poor in the rotation priority. .

[0049]

As described above, the present invention has the following effects.

Since the priority component included in the packet information is extracted and the priority is reconfigured each time a packet is received, the priority is adjusted efficiently according to the received packet information and the efficiency is improved. Transfer processing is possible. In addition, if the long-term suspender is monitored and detected, the priority is changed to a higher priority, so that the processing delay of the long-term suspender is reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a priority arbitration device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a dynamic priority reconfiguration / arbitration circuit 40;

FIG. 3 is a configuration diagram of a long-term on-hold person monitoring circuit 50;

FIG. 4 is a timing chart illustrating the operation of the present embodiment.

FIG. 5 is a flowchart illustrating the operation of the embodiment.

[Explanation of symbols]

10 ₁ to 10 _n packets 11 ₁ to 11 _n lines 20 ₁ to 20 _n request processing circuit 21 ₁ through 21 _n bus use request signal 22 ₁ through 22 _n priority code signal 23 ₁ ~ 23 _n bus request enable signal 30 ₁ to 30 _n priority analysis circuit _{31 1 ~31 n, 32 1 ~32} n, 33 1 ~33 n, 34 1 ~
34 _n priority signal 35 _{1 to} 35 _n bus use permission signal 36 _{1 to} 36 ₄ priority arbitration request signal 37 _{1 to} 37 ₄ request permission signal 40 dynamic priority reconfiguration / arbitration circuit 41 _{1 to} 41 _n priority arbitration request signal 42 ₁ through 42 _n arbitration authorization response confirmation signal 48 responsive check permission signal 50 long pending user monitoring circuit 51 ₁ to 51 _n acknowledgment signal 70 dynamically reconfigurable circuit 80 ₁ to 80 ₄ rotating priority circuit 90 fixed priority arbitration Circuit 110 _{1 to} 110 _n AND circuit 120 _{1 to} 120 _n Counter 201 _{1 to} 201 _n steps

Claims (2)

(57) [Claims] When a packet is received from a corresponding line, a priority code component is extracted from the packet and output as a priority code signal, and a request for permitting packet data transfer is made. A request processing circuit that stops the permission request when receiving the signal, and a priority processing unit that is provided for each request processing circuit and receives a priority code signal from the corresponding request processing circuit. A priority analysis circuit that outputs a priority signal and receives a request permission signal and outputs the request permission signal to a corresponding request processing circuit; and accommodates a priority signal from each of the priority analysis circuits. the classified by priority, then performs the priority arbitration process, the dynamic priority reconfiguration-arbitration circuit to return the request enable signal to the priority analysis circuit in question the from the request processing circuit To monitor the availability request,該許Allowed needed
Request source that is not sent even if the request permission is sent for a long time
If there is, make the requester's priority higher than other requesters.
Arbitration request to the dynamic priority reconfiguration / arbitration circuit
Request, and the request permission is returned to the dynamic priority
If it is returned from the configuration / arbitration circuit,
A long-term on-hold user monitoring circuit for sending to the request processing circuit, wherein the dynamic priority reconfiguration / arbitration circuit performs the respective priority analysis
Priority signals from the circuit are accommodated and these are assigned to priority.
Output a priority arbitration request signal for each priority,
When a request permission signal is received, a request is sent to the corresponding request processing circuit.
A dynamic reconfigurable circuit that outputs a request permission signal,
Provided by the dynamic reconfigurable circuit from the priority of the priority
Upon receiving the arbitration request signal, the arbitration request signal is
When the request permission signal is delivered, the rotation
Performs preprocessing and requests permission signal corresponding to the selected line
Output to the dynamic reconfigurable circuit,
Arbitration request signal group from the switching priority circuit and the long-term hold user
Receives a group of arbitration request signals from the monitoring circuit,
The highest priority among the arbitration request signal group from the priority circuit
Select the arbitration request signal and respond to the selected arbitration request signal
To the corresponding rotation priority circuit
The arbitration request signal group from the rotation priority circuit and the long term
Arbitration request signals from the pending user monitoring circuit competed
Arbitration with the highest priority among the latter arbitration request signals
Fixed priority mode that outputs a request permission signal corresponding to the request signal
Priority arbitration device including stop circuit. 2. The long-term on-hold user monitoring circuit is provided for each request processing circuit. When receiving a permission request from the request processing circuit, the long-term on-hold user monitoring circuit enters a countable state, and the fixed priority arbitration circuit outputs a request permission signal. Counting is performed each time a response confirmation permission signal output with the counter is received, and when a predetermined value is reached,
A counter that outputs a priority arbitration request signal to the fixed priority arbitration circuit, and is provided for each request processing circuit, and when a request permission signal selected from the fixed priority arbitration circuit is output while receiving a permission request, and a gate circuit to return the request enable signal to the request processing circuits corresponding, apparatus according to claim 1.