JPH09179814A - Arbitration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a request of low priority from having a timeout when requests of high priority are successively generated in a system wherein plural modules share one resource. SOLUTION: In the system wherein plural modules 1-4 share one resource 9, requests are written in a buffer 6 in their issue order unless plural modules 1-4 issue the requests at the same time, but when plural modules 1-4 issues requests at the same time, they are written in the buffer in specific priority order. Then the requests are read out of the buffer 6 to allow the resource to be used in the order of the storage in the buffer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arbitration method in a system in which a plurality of modules such as I / O modules share one resource, and in particular, by giving the right to use the resource in the order of issuing requests for the resource, The present invention relates to an arbitration method that can prevent a request with a low priority from timing out even when requests with a high priority continue.

[0002]

2. Description of the Related Art Conventionally, as an arbitration technique of this type, as disclosed in Japanese Patent Laid-Open No. 5-94409, when there is only one request for a resource, the module that issued the request is provided with a bus. By using the counter that counts the bus occupation time value when two or more requests conflict,
Some give the right to use the bus to a module with a small counter time value.

[0003]

In recent years, the computer system has been remarkably increased in size, and the number of modules connected to the bus has been increased accordingly.

However, in the above-mentioned conventional arbitration method, since the right to use the bus is given according to the counter timing value at the time of the priority determination of the request, if the requests with a small counter timing value continue, the counter timing value increases. Requests are not accepted and there is a problem that a timeout occurs.

An object of the present invention is to give a resource use permission in the order of request issuance in a system in which a plurality of modules share one resource, so that even if requests with a high priority are consecutive, the priority is low. It is to provide an arbitration method that can prevent request timeout.

[0006]

In order to achieve the above object, the first method of the present invention monitors the request issuance status of a plurality of modules, and if the plurality of modules do not issue requests at the same time, The requests are written in the buffer in the order of issuance, and when a plurality of modules issue the requests at the same time, the requests are written in the buffer in a predetermined priority order, and the resource use permission is given in the order of storage in the buffer. .

That is, when a plurality of modules issue requests at the same time, prior to writing the requests in the buffer, priority arbitration is performed and the requests are written in the buffer, and resource use permission is given in the order of storage in the buffer. It is the one.

The second method of the present invention monitors the request issuance status of a plurality of modules, writes all the requests in a buffer at the timing when one or more requests are issued, and stores the contents of the buffer. If only one request is issued when the request is read at the priority determination timing, the resource usage right is given to that module, and if multiple requests are issued, the request is issued with a predetermined priority. The resource usage right is given to each module.

That is, when a plurality of modules issue requests at the same time, all of them are written in a buffer, and when a plurality of requests are issued when the contents of the buffer are read at a predetermined timing, a predetermined request is issued. The resource usage right is given to each module issuing a request in the priority order of.

Therefore, according to the method of the present invention, even if the request has a low priority, if there is no other module issuing the request, the use permission of the resource is immediately given. This makes it possible to prevent a time-out of a request with a low priority even when requests with a high priority continue.

Here, the resources mean all resources shared by a plurality of modules such as a memory, a dedicated arithmetic circuit, and a special control circuit.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of an embodiment of the present invention, in which 1-4 are resources 9 through a bus 8.
Is a shared module. Below, each module is M
Abbreviated as JA to MJD.

Reference numeral 5 is a buffer write control circuit (hereinafter abbreviated as BWC) for writing the request signals RQA11 to RQD14 issued from MJA1 to MJD4 in the request storage buffer 6, and 6 is a request signal issued from MJA1 to MJD4. A request storage buffer (hereinafter abbreviated as RBF) for storing the RQA11 to RQD14, and a resource use permission circuit (hereinafter abbreviated as GRC) 7 are provided. 11 to 14 are request signals issued from MJA1 to MJD4, and 21 to 24 are MJA1 to MJD.
4 use permission signal of resource 9 (SGRA to SG
RD), 31 is a data write enable signal (WE) from BWC5 to RBF6, and 32 is BWC5 to R
Write data signal (WD) to BF6, 33 is RB
GRC that "valid request" is stored in F6
7 is a buffer valid signal (BV) transmitted to 7 and 34 is GRC7.
Is a data signal (RD) read from RBF6, and 35 is a read enable signal (RE) from GRC7 to RBF6.

Next, the operation of each block shown in FIG. 1 will be described with reference to a time chart.

First Arbitration Method First, when a plurality of modules 1 to 4 do not issue requests at the same time, the requests are written in the RBF 6 in the order of request issuance, and when a plurality of modules 1 to 4 issue requests at the same time, a predetermined priority is given. Write to RBF6 in order, R
First to give permission to use resource 9 in the order of storage in BF6
The arbitration method will be described with reference to the time chart of FIG.

In the first arbitration method, the BW
When a plurality of MJA1 to MJD4 do not issue request signals RQA11 to RQD14 at the same time, C5 is RBF in the order of issuing the request signals RQA11 to RQD14.
6, and when a plurality of MJA1 to MJD4 issue request signals RQA11 to RQD14 at the same time, they are written to RBF6 with an appropriate priority. Also, GRC7
Gives permission to use the resource 9 in the order of storage in the RBF 6. In this example, the priority of BWC5 is RQA11, R
It is assumed that the order of priority is QB12, RQC13, and RQD14 in that order.

(1). MJA1 RQ at timing T1
Issue A11.

(2). MJB2 RQ at timing T2
Issue B12. BWC5 constantly monitors requests from each module, but RQA1 from MJA1
When 1 is detected, WE31 indicating that the number of write data is “1” is issued, and at the same time, write data RQA11 is output as WD32 and written in RBF6.

(3). MJC3 RQ at timing T3
C13 is issued, and MJD4 issues RQD14. The BWC5 detects the RQB13, issues the WE31 indicating that the number of write data is "1", and at the same time, outputs the write data RQB12 as the WD32.
Write to RBF6. RBF6 issues BV31 and G
At the same time as notifying RC7 that valid data exists in RBF6, it outputs RQA11 to RD34.

GRC 7 issues RE 35 to RBF 6 if resource 9 is available. At this time, BV3
Since 3 is valid and RQA11 is output to RD34, SGRA21 is issued to MJA1.

As a result, the resource 9
Permission to use.

(4). At timing T4, MJA1 is S
GRA21 is detected and RQA11 is terminated. BWC5
Detects RQC13 and RQD14, issues WE31 indicating that the number of write data is “2”, and at the same time, writes write data RQC13 and RQD1 as WD32.
4 is output and written in RBF6.

At this time, the RBF 6 has the RV 33 and the RE 35.
Are valid at the same time, so RD34 is updated and RQB12
Is output. The GRC 7 issues the RE 35 because the resource is in a usable state. At this time, since BV33 is valid and RQB12 is output to RD34,
Issue SGRB22 to MJA12.

As a result, the use permission of the resource 9 is given to the MJA 12.

(5). At timing T5, MJA1 issues RQA11 again. On the other hand, MJB2 is SGR
RQB12 is terminated by detecting B22.

Since the BV 33 and the RE 35 are valid at the same time, the RBF 6 updates the RD 34 and outputs the RQC 13. GRC 7 terminates RE 35 because the resource is in an unavailable state. Also, BV33 is valid and RQC13 is output to RD34.
SGRC23 is not issued to 13.

(6). BWC5 RQ at timing T6
A11 is detected, WE31 indicating that the number of write data is “1” is issued, and at the same time, write data RQA11 is output as WD32 and written to RBF6.

At this time, since the RE 35 is invalid, the RBF 6 holds the RQC 13 without updating the RD 34. G
RC7 issues RE35 because resource 9 is available. Also, BV33 is valid, and RD34 has RQC.
13 is output, so SGRC for MJA13
Issue 23.

As a result, the use permission of the resource 9 is given to the MJA 13.

(7). MJC3 is SG at timing T7
The detection of RC23 terminates the RQC13.
Since the BV 33 and the RE 35 are valid at the same time, the RBF 6 updates the RD 34 and outputs the RQD 14.

The GRC 7 issues the RE 35 because the resource 9 is available. At this time, BV3
Since 3 is valid and the RQD 14 is output to the RD 34, the SGRD 24 is issued to the MJA 14.

This gives the MJA 14 permission to use the resource 9.

(8). MJD4 is SG at timing T8
RQD14 is terminated by detecting RD24.
Since the BV 33 and the RE 35 are simultaneously valid, the RBF 6 updates the RD 34 and outputs the RQA 11.

GRC 7 issues RE 35 because resource 9 is ready for use. At this time, BV3
Since 3 is valid and RQA11 is output to RD34, SGRA21 is issued to MJA11.

As a result, the use permission of the resource 9 is given to the MJA 11.

(9). MJA1 is SG at timing T9
RQA11 is terminated by detecting RA21.
In RBF6, BV33 and RE35 are valid at the same time, and RB
Since there is no valid request in F6, BV33 is terminated.

By such an operation, each MJA11-M
The JA 14 can obtain the usage right of the resource 9 in the order of request issuance.

As a result, even if the request has a low priority, the use permission of the resource 9 is immediately given if there is no other module issuing the request. As a result, it is possible to prevent a request with a low priority from timing out even when requests with a high priority continue.

When the request issuance timings are the same, the right to use the resource 9 is given to the module having a higher priority.

That is, it is possible to realize the operation of giving the right to use the resource 9 to a request with a low priority while maintaining the mechanism of prioritizing the request according to a predetermined priority.

Second Arbitration Method Next, all the requests that are valid at the timing when one or more requests are issued are written to the RBF 6,
If only one request is issued when the contents of RBF6 are read at the request priority determination timing, the right to use the resource is given to that module, and if multiple requests are issued, they are assigned the predetermined priority. A second arbitration method of granting the resource use right to each module issuing a request will be described with reference to the time chart of FIG.

In the second arbitration method, BW
C5 is a circuit that writes all valid requests to the RBF 6 at the timing when one or more requests are issued. Further, if only one request is issued at one timing, the GRC 7 gives a usage right to a resource to the module, and if a plurality of requests are issued at one timing, the timing is given in a predetermined priority order. This is a circuit that grants the resource usage right to the module issuing the request to.

In this example, the priority of GRC7 is RQA1.
It is assumed that the priority order is higher in the order of 1, RQB12, RQC13, RQD14.

(1). MJA1 RQ at timing T1
Issue A11.

(2). MJB2 RQ at timing T2
Issue B12. BWC5 detects RQA11 and W
Write data RQ to WD32 at the same time when E31 is issued
A11 is output and written in RBF6.

(3). MJC3 RQ at timing T3
C13 is issued, and MJD4 issues RQD14. The BWC5 detects the RQB12, issues the WE31, and at the same time outputs the write data RQB12 as the WD32 and writes it in the RBF6.

RBF6 issues BV31 and GRC7
To the RBF 6, and at the same time, the RQA 11 is output to the RD 34.

GRC 7 issues RE 35 to RBF 6 if resource 9 is available. At this time, BV
Since 33 is valid and RQA11 is output to RD34, SGRA21 is issued to MJA1.

As a result, the resource 9
The right to use is given.

(4). MJA1 is SG at timing T4
RQA11 is terminated by detecting RA21. BWC5 detects RQC13 and RQD14, and
At the same time when E31 is issued, write data RQC13 and RQD14 are output as WD32 and written to RBF6.

Since the RV 33 and the RE 35 are valid at the same time, the RBF 6 updates the RD 34 and outputs the RQB 12.

GRC 7 terminates RE 35 because resource 9 is unavailable. At this time, BV33 is valid and RQB12 is output to RD34.
SGRB22 is not issued to JB2.

(5). RQ for MJA1 at timing T5
Issue A11. Since the RE 35 is invalid, the RBF 6 holds the RQB 12 without updating the RD 34.

GRC 7 issues RE 35 because resource 9 is available. At this time, since BV33 is valid and RQC13 is output to RD34, MJ
Issue SGRB22 to B2.

As a result, the resource 9 is transmitted to the MJB2.
The right to use is given.

(6). MJB2 is SG at timing T6
RQB12 is terminated by detecting RB22.
The BWC 5 detects the RQA 11 and issues the WE 31, and at the same time, outputs the write data RQA 11 as the WD 32 and writes it in the RBF 6.

Since RE35 is effective for RBF6,
The RD34 is updated and the RQC13 and RQD14 are output.

The resource 9 can be used in the GRC 7, but since two requests of the RQC 13 and the RQD 14 are output to the RD 34, the RE 35 is terminated to prevent the RD 34 from being updated. At this time, the BV 33 is valid, and the RQC 13 has a high priority in the RQC 13 and the RQD 14, so the SGRC 23 is issued to the MJC 3.

As a result, the resource 9 is transmitted to the MJC3.
The right to use is given.

(7). MJC3 is SG at timing T7
The detection of RC23 terminates the RQC13.
RBF6 is invalid for RE35 at the same time, so RD3
4 is not updated and RQC13 and RQD14 are output.

GRC 7 issues RE 35 because resource 9 is available. At this time, BV33 is valid and RQC13 and RQD14 are output to RD34, but SGRC23 was issued at timing T6, so M
Issue SGRD24 to JD4.

As a result, the resource 9 is transmitted to the MJD4.
The right to use is given.

(8). MJD4 is SG at timing T8
RQD14 is terminated by detecting RD24.
Since the BV 33 and the RE 35 are valid at the same time, the RBF 6 updates the RD 34 and outputs the RQA 11.

The GRC 7 issues the RE 35 because the resource 9 is available. At this time, since BV33 is valid and RQA11 is output to RD34, MJ
Issue SGRA21 to A1.

As a result, the resource 9
The right to use is given.

(9). MJA1 is SG at timing T9
RQA11 is terminated by detecting RA21.
RBF6 terminates BV33 because BV33 and RE35 are valid at the same time and there is no valid data in the buffer.

By these operations, even if the request has a low priority, if there is no other module issuing the request, the use permission of the resource 9 is immediately given. As a result, it is possible to prevent a request with a low priority from timing out even when requests with a high priority continue.

When the requests are issued at the same timing, the right to use the resource 9 is given to the module having the higher priority.

That is, it is possible to realize the operation of giving the right to use the resource 9 to a request with a low priority while maintaining the mechanism of prioritizing the request according to a predetermined priority.

The present invention can be applied not only to a bus to which a plurality of modules are connected but also to all systems in which a plurality of circuits share one circuit (resource) inside an LSI.

[0072]

As described above, according to the present invention, in a system in which one resource is shared by a plurality of modules, if a plurality of modules do not issue requests at the same time, a plurality of modules are written in a buffer in the order of request issuance. When issuing requests at the same time, by writing to a buffer with a predetermined priority and giving resource use permission in the order of storage in the buffer, the resource use right can be obtained in the order of request issuance. Even if the request has a low priority, if there is no other module issuing the request, the resource use permission is immediately given. As a result, it is possible to prevent a request with a low priority from timing out even when requests with a high priority continue.

When a plurality of modules issue requests at the same time, they are all written in the buffer, and when a plurality of requests are issued when the contents of the buffer are read out at a predetermined timing, a predetermined request is issued. Since the resource usage right is given to each module issuing a request with the priority of, the timeout of the request with the low priority can be prevented even when the requests with the high priority continue in the same manner as described above. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the first arbitration method of the present invention.

FIG. 3 is a timing chart for explaining a second arbitration method of the present invention.

[Explanation of symbols]

1 to 4 ... Module, 5 ... Buffer write control circuit, 6
... request storage buffer, 7 ... resource use permission circuit, 11-14 ... request signal, 21-24 ... resource use permission signal, 31 ... write enable signal, 32 ...
Write data signal, 33 ... Buffer valid signal, 34 ... Data signal, 35 ... Read enable signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Moriyama 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Stock Company Hitachi Office Systems Division (72) Masahide Tsuboi Ikegami, Haruka-cho, Owariasaichi, Aichi Shares Company Hitachi Ltd. Office Systems Division (72) Inventor Koichi Okazawa 1099 Ozenji, Aso-ku, Kawasaki, Kanagawa Stock Company Hitachi Systems Development Laboratory (72) Inventor Masaya Umemura 1099 Ozenji, Aso-ku, Kawasaki, Kanagawa Ceremony Company Hitachi Ltd. System Development Laboratory (72) Inventor Hiroshi Murashima 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Stock Company Hitachi Ltd. Office Systems Division (72) Inventor Masumi Terao 10-3 Sakae, Naka-ku, Nagoya-shi, Aichi No. 22 Nippon Chubu Software Co., Ltd. House (72) inventor Mitsuru Murai Nagoya, Aichi Prefecture, Naka-ku Sakae Third Street No. 10 No. 22 Date start-central software within Co., Ltd.

Claims (2)

[Claims] 1. An arbitration method in a system in which a plurality of modules share one resource through a shared bus, wherein the request issuance status of a plurality of modules is monitored, and when the plurality of modules do not issue a request at the same time, Write requests to the buffer in the order of issue,
An arbitration method, wherein when a plurality of modules issue requests at the same time, the requests are written in the buffer in a predetermined priority order, and resource use permission is given in the order of storage in the buffer. 2. A method of arbitration in a system in which a plurality of modules share one resource through a shared bus, wherein request issuing states of a plurality of modules are monitored and all the requests are issued at a timing when one or more requests are issued. If only one request is issued when the request is written in the buffer and the contents of the buffer are read at the request priority judgment timing, the resource usage right is given to the module and multiple requests are issued. If so, the arbitration method is characterized in that each module issuing a request with a predetermined priority is given a right to use the resource.