JP2004206369A - Access method and access program to common resource - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve a problem of prolonged processing time because of convergence of a common bus for poling lock release and waiting for release in the case that accessing common resource is locked in a conventional method which needs an exclusive process at the time a plurality of processors access to the common resource of a common memory. <P>SOLUTION: Processors 1, 4 access to the common resource of the common memory 9 via a common bus 8 in the method which includes a dual port RAM 7 connected to local buses 3, 6 of each processor and management information of each common resource. The processor 1 matches a tag number to the dual port RAM 7 and stores writing data beforehand at the time of accessing for writing and the tag number is set to the management information and a writing process is executed if the management information is lock-off. As for accessing for reading of the processor 4 during the above period of time, the tag number is read from the management information and data are read from the dual port RAM 7. With the access for writing, the tag number corresponding to writing data stored beforehand is set to the management information as well. This writing process is achieved also by the processor 1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an access program for accessing a common resource on a common memory commonly used by a plurality of processors.
[0002]
[Prior art]
When a multiprocessor has a common memory and accesses a common resource in the common memory, exclusive processing is generally performed using a lock flag for each common resource so that multiple processors do not change the same common resource at the same time. I do.
[0003]
The processor that first accesses the common resource (eg, the first processor) sets a lock flag and inhibits other processors from accessing this common resource. The first processor that has set the lock flag clears the lock flag when access to the common resource ends.
[0004]
If the lock flag is set when another processor accesses the common resource, the other resource must wait until the lock flag is cleared because the common resource cannot be accessed. Other processors must always poll the lock flag because it is not known when the lock flag will be cleared.
[0005]
As an example of such a multiprocessor system in which a plurality of processors access shared data in a memory via a bus, while one processor is accessing shared data in a memory, the other processor can access the shared data from the other processor. There is a multiprocessor system including a memory access control circuit that rejects the memory access request of the other processor and receives a memory access request from the other processor to an address different from the address of the shared data (for example, see Patent Document 1). ).
[0006]
[Patent Document 1]
JP-A-5-210640 (page 2, line 2 to 14, paragraph [0086])
[0007]
[Problems to be solved by the invention]
In the above multiprocessor example, the other processor temporarily suspends a task or job that performs data access under exclusive control, and switches to a task or job that accesses data that is not under exclusive control. This is to reduce the decrease.
[0008]
Therefore, it cannot be applied to a job that requires real-time processing by the other processor. In other words, there is a problem that the processing time of the job waiting in the exclusive control becomes longer.
[0009]
Further, it does not teach the timing when the other processor is permitted to receive an access request to the target shared data, and does not significantly reduce the polling.
[0010]
Generally, a common memory is connected to a common bus, and the common bus has a low access speed due to the need for bus arbitration and a long line length. Therefore, there is also a problem that a common bus shared by a plurality of processors is congested and the performance of the entire system is reduced.
[0011]
[Means for Solving the Problems]
A first common resource access method according to the present invention is a method in which two processors access a common resource on a common memory through a common bus, wherein each processor can access a common resource through a local bus; A plurality of unique tag numbers used by each processor are defined except for an initial value and a plurality of predetermined values, and are defined so that the processor can be identified. The common resource management storage has a buffer corresponding to a tag number, and stores, in the common resource management storage, the tag number also serving as a lock flag of the common resource, the initial value indicating that the lock flag is off, or that the lock flag is on and being read. The plurality of predetermined values indicated for each processor are stored as management information for each common resource, and when writing to the common resource, the processor The write data is stored in the buffer corresponding to the tag number of the dual port memory in advance, the management information to be accessed is checked, and if the initial value, that is, the lock flag is off, the management information is updated to the tag number. After that, writing to the common resource and initializing the tag number of the management information, that is, the means for turning off the lock flag, and at the time of reading to the common resource, checking the management information to be accessed and checking the initial value or any of A predetermined value, that is, if the lock flag is off or being read, the management information is updated to its own predetermined value, reading from the common resource is performed, and if the management information is not updated, the means for initializing the management information is provided. If the tag number is set by the check, there is provided a means for reading data from the buffer of the dual port memory indicated by the tag number.
[0012]
According to a second access method to the common resource of the present invention, in the access method to the first common resource, the processor determines a tag number when writing to the common resource and transfers the write data to the dual port. It is stored in advance in a buffer corresponding to the tag number in the memory, the management information to be accessed is checked, and if it is an initial value, the management information is updated to the tag number, written to a common resource, and the management information is written. Means for retrieving the write data from the buffer corresponding to the tag number of the dual port memory if it has been updated to another tag number and writing it to the common resource, and then initializing the management information; If the tag number or any predetermined value is set in the management information, that is, if the lock is on, the management information is updated to the tag number when the write data is stored in the dual port memory. Means, when reading out to the common resource, check the management information to be accessed, and if it is an initial value or any predetermined value, update it to its own predetermined value, read from the common resource, and Check the information, and if it has not been updated, immediately extract the write data from the buffer corresponding to the tag number of the dual port memory if it has been updated to the tag number and write it to the common resource. And means for reading data from the buffer of the dual port memory indicated by the tag number if the tag number is set in the management information by the check.
[0013]
A third method of accessing a common resource according to the present invention is a method in which two processors access a common resource on a common memory through a common bus, wherein each processor can access a common resource through a local bus; A common resource management storage, a plurality of unique tag numbers used by each processor are defined, a buffer corresponding to the tag number is provided on the dual port memory, and a lock is provided in the common resource management storage. A management information including a flag, a reading flag, a processor number and a tag number is held for each common resource, and the processor determines a tag number when writing to the common resource, and writes the tag number of the dual port memory in the dual port memory. Store in the corresponding buffer in advance, check the management information of the access target, and if the lock flag is off, turn it on and Means for updating the management information, writing to the common resource, and turning off the lock flag of the management information, and for reading out to the common resource, Check the management information, if the lock flag is off or the reading flag is on, turn on the lock flag and reading flag, update the management information with the processor number as its own number, read from the common resource, and perform management. Means for confirming the information and clearing the lock flag or the read flag if the processor number is not updated; and dual means indicated by the tag number of the management information if the lock flag is on and the read flag is off in the management information check. It is characterized by having means for reading data from the buffer of the port memory.
[0014]
According to a fourth common resource access method of the present invention, in the third common resource access method, the processor determines a tag number when writing to the common resource, and writes the write data to the dual resource. The management information to be accessed is stored in advance in a buffer corresponding to the tag number in the port memory, and if the lock flag is off, the lock flag is turned on, the processor number is set to the own number, and the tag number area is the management information as the tag number. Is updated, the common resource is written, the management information is checked, and if the tag number is updated, the write data is taken out from the corresponding buffer of the dual port memory, written to the common resource, and then the lock flag is set. Means for turning off the tag number of the management information if the lock flag is on in the above check, and the tag number when the write data is stored in the dual port memory. Means to turn off the read flag and to check the management information of the access target when reading to the common resource. If the lock flag is off or the read flag is on, the lock flag and the read flag are turned on. The processor number updates the management information as its own number, reads from the common resource, checks the management information, and if it is not updated, immediately clears the lock flag and the reading flag, and turns off the reading flag. If there is, the write data is taken out from the buffer of the dual port memory indicated by the tag number of the management information, written into the common resource, and then the lock flag is turned off. If it is off, there must be means for reading data from the buffer of the dual port memory indicated by the tag number of the management information. And butterflies.
[0015]
According to a fifth access method to a common resource of the present invention, in the first, second, third, or fourth access method to a common resource, the processor is a storage area for storing a next-use tag number. Means for setting the tag number read from the storage area when writing to a common resource occurs as the tag number when storing the data in the dual port memory, and incrementing or starting the tag number of the storage area upon completion of the processing of the write request It has means for circulating and updating the values, and the tag numbers assigned to the own processor are cyclically used in numerical order.
[0016]
A sixth access method to the common resource according to the present invention is the access method to the second or fourth common resource, wherein the tag or the validity display flag is stored in the dual port memory for each tag number. The processor also refers to the tag area to check the storage area for storing the tag number for the next time, and the tag area read from the storage area when writing to the common resource occurs, by referring to the tag area. If it is not empty, the storage area is incremented or circulated until an empty number is reached, and the storage area is updated and then set as the determined tag number. When the write data of the tag number corresponding buffer of the dual port memory is stored in the common resource, the corresponding tag number of the tag area is invalidated. And having means, the means for updating is circulated tag number of the storage is incremented to the start value at the end of processing write requests.
[0017]
According to a seventh aspect of the present invention, there is provided the access method to any one of the first to sixth common resources, wherein the two processors are N processors, Is an N-port memory.
[0018]
The first access program to the common resource of the present invention determines the tag number when writing to the common resource on the common memory accessed by the two processors through the common bus, and the local bus of each processor is connected. The dual port memory is accessed, the write data is stored in advance in the buffer corresponding to the tag number, the management information of the common resource to be accessed is checked, and if the initial value, that is, the lock flag is off, the management information is stored in the tag number. After the update, the common resource is written and the tag number of the management information is initialized, that is, the lock flag is turned off. In reading the common resource, the management information of the common resource to be accessed is checked and the initial value is checked. If any one of the predetermined values, that is, the lock flag is off or being read, the management information is updated to its own predetermined value, read from the common resource, and the management information is There the procedure for initializing this Without being updated, and having a said dual-port read the file data from the buffer memory associated with it if the tag number is set in the check.
[0019]
The second access program for a common resource according to the present invention, in the access program for the first common resource, determines a tag number when writing to the common resource, and writes the write data to the dual port memory. The management information of the common resource to be accessed is stored in advance in the buffer corresponding to the tag number, and if it is the initial value, the management information is updated to the tag number, and the management information is written to the common resource. Confirming that the tag has been updated to another tag number, and taking out write data from the buffer corresponding to the tag number of the dual port memory, writing it to the common resource, and then initializing the management information; If it is determined in the check that the management information is the tag number or any predetermined value, that is, lock-on, the management information is updated to the tag number when the write data is stored in the dual port memory. When reading to the common resource, the management information to be accessed is checked, and if it is an initial value or any predetermined value, this is updated to its own predetermined value, and reading from the common resource is performed. Check the management information, and if it has not been updated, immediately retrieve the write data from the buffer corresponding to that tag number in the dual port memory if it has been updated to the tag number, write it to the common resource, and then manage each It is characterized by having a procedure for initializing information and a procedure for reading data from the buffer of the dual port memory indicated by the tag number if the tag number is set in the management information in the check.
[0020]
According to the third access program to the common resource of the present invention, the tag number is determined at the time of writing to the common resource on the common memory accessed by the two processors through the common bus, and the local bus of each processor is connected. The dual port memory is accessed, the write data is stored in the buffer corresponding to the tag number in advance, the management information to be accessed is checked, and if the lock flag is off, this is turned on, the processor number is set to the own number, and the tag number is set. The area updates the management information as the tag number, writes in the common resource, turns off the lock flag of the management information, and checks the management information to be accessed when reading out the common resource, and checks the lock flag. Is off or the reading flag is on, the lock flag and reading flag are turned on, and the processor number is managed as the own number. Procedure for updating information, reading from common resources, checking management information and clearing the lock flag or reading flag if the processor number has not been updated, and reading the management information check when the lock flag is on and the lock flag is on If the flag is off, a procedure for reading data from the buffer of the dual port memory indicated by the tag number of the management information is provided.
[0021]
The fourth common resource access program according to the present invention, in the third common resource access program, determines a tag number when writing to the common resource, and writes the write data to the dual port memory. The control information is stored in advance in the buffer corresponding to the tag number, and the management information to be accessed is checked. If the lock flag is off, this is turned on, the processor number is set to the own number, and the tag number area updates the management information as the tag number. Write to the common resource, check the management information, and if the tag number has been updated, take out the write data from the corresponding buffer of the dual port memory, write to the common resource, and turn off the lock flag. If the lock flag is on in the procedure and the check above, the tag number of the management information is stored in the dual port memory. The procedure of updating and turning off the reading flag and checking the management information of the access target at the time of reading to the common resource, and if the lock flag is off or the reading flag is on, the lock flag and the reading flag are turned on. The processor number updates the management information as its own number, reads from the common resource, checks the management information, and if it is not updated, immediately clears the lock flag and the reading flag, and turns off the reading flag. If there is any, the write data is taken out from the buffer of the dual port memory indicated by the tag number of the management information, written into the common resource, and then the lock flag is turned off. If off, have a procedure to read data from the dual port memory buffer indicated by the tag number in the management information And it features.
[0022]
The fifth common resource access program according to the present invention is the first, second, third, or fourth common resource access program, wherein the next common tag is used when writing to the common resource. There is a procedure for using the tag number read from the number storage area as a tag number when storing in the dual port memory, and a procedure for incrementing or circulating the tag number of the storage area to a start value and updating at the end of processing of a write request. The tag numbers assigned to the own processor are cyclically used in numerical order.
[0023]
The sixth access program to the common resource according to the present invention is the program for accessing the second or fourth common resource, which is read from the next tag number storage area when writing to the common resource. Check the vacancy of the tag number by referring to the tag number management area on the dual port memory, and if not, increment or circulate until the vacant number is reached and update the storage area, and then set the determined tag number respectively. After completing the procedure and storing the write data in the buffer corresponding to the tag number of the dual port memory, the corresponding tag number in the tag number management area is validated, and the write data of the buffer corresponding to the tag number of the dual port memory is stored in the common resource. When the writing is completed, the corresponding tag number in the tag number management area is invalidated, and the number of the next tag number storage area is entered upon completion of the write request processing. And having a decrement or procedure for updating is circulated to the starting value.
[0024]
A seventh common resource access program according to the present invention is the common memory access program according to any of the first to sixth common resources, wherein the common resources are accessed by N processors through a common bus. The dual port memory may be an N port memory connected to a local bus of N processors as the above common resource.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described.
[0026]
FIG. 1 is a diagram showing a configuration of a multiprocessor system including an access method to a common resource according to the present invention.
[0027]
An example of two multiprocessors will be described with reference to FIG. The first processor 1 has a local RAM / boot ROM 2 dedicated to the first processor 1 connected via a local bus 3.
[0028]
Similarly, the second processor 4 has a local RAM / boot ROM 5 dedicated to the second processor 4 connected via a local bus 6.
[0029]
A common memory 9 commonly used by the first processor 1 and the second processor 4 is connected via a common bus 8. Since the common bus 8 is used commonly by the first processor 1 and the second processor 4, bus arbitration is performed so that bus accesses do not overlap.
[0030]
A dual port RAM 7 for exchanging data between the first processor 1 and the second processor 4 at high speed is provided. The first processor 1 and the second processor 4 access the dual port RAM 7 through the local buses 3 and 6, respectively. Access can be performed independently and in parallel.
[0031]
When the first processor 1 or the second processor 4 is performing write access to the common resource of the common memory 9 via the common bus 8, it is locked to the common resource so that the other processor does not access the same common resource. A flag is set to prohibit access by the partner processor.
[0032]
Also, assuming that the partner processor accesses the same common resource, each processor writes the same information in the dual port RAM 7 in advance. In order to associate the information of the dual port RAM 7 with the information of the common resource, the data of the dual port RAM 7 and the data of the common resource on the common memory 9 are tagged in common.
[0033]
At this time, if the other processor has read-accessed the same common resource, the lock bit is set. Therefore, the other processor checks the tag attached to the common resource on the common memory 9 and reads the same tag on the dual port RAM 7. And reads the data on the dual port RAM 7 as a common resource on the common memory 9.
[0034]
At this time, if the partner processor writes data to be written to the common memory 9 on the dual port RAM 7 and then performs write access to the same common resource, the lock bit is set. The tag attached to the common resource is changed to its own tag number to indicate that the change has been made.
[0035]
When the access to the common resource of the common memory 9 is completed, the first processor checks whether the tag number of the common resource has been rewritten. If the tag number has been rewritten, the data associated with the tag number on the dual port RAM 7 Is copied to the corresponding resource in the common memory 9, and the lock flag of the common resource is released.
[0036]
Note that the access control processing for the common resource can be realized by a program of the first processor 1 or the second processor 4.
[0037]
Next, an example of the contents of the common memory will be described with reference to FIG. The common memory 9 includes a common resource area 92 including common resources (0) 92-0,..., Common resources (m) 92-m, and common resource (0) management / address information 91-0 of these common resources. .., Common resource (m) management ・ has a resource management area 91 including address information 91-m.
[0038]
The management / address information of each common resource includes the management information and the pointer of the common resource. The management information is normally cleared to 0, but in the locked state, a tag number also serving as a lock flag is set.
[0039]
The tag number is a number for identifying write data previously written in the dual port RAM 7 before writing to the common resource, and is set to a number other than 0 so as to also serve as a lock flag. Make sure that the number is the set number.
[0040]
Further, in the common resource management information, predetermined values 99 and 98 (pseudo tag numbers of read type) indicating that the first processor 1 and the second processor 4 are respectively reading are set. It is excluded as an identification number.
[0041]
The number of tag numbers is determined by the number that may simultaneously access the resources of the common memory. For example, if there are about six that may be accessed simultaneously, ten tag numbers are prepared by looking at the margin.
[0042]
Since the tag numbers are managed separately by the first processor and the second processor, they must be unique numbers to distinguish them. For example, the tag number of the first processor uses 10 to 19, and the second processor uses 20 to 29.
[0043]
In the example of the use of the first processor, the first tag number is 10, the next is 11, 12,..., And when it becomes 19, the next returns to 10.
[0044]
Similarly, the second processor prepares tag numbers 20 to 29 and uses them as 20, 21, 22,..., And returns to 20 when the tag number reaches 29.
[0045]
The buffer for the dual port RAM 7 is prepared for the tag number. That is, ten units are reserved for the first processor and ten units are reserved for the second processor.
[0046]
FIG. 3 is a diagram showing an example of the contents of the dual port RAM 7. A tag number is set in the tag area 71. The buffer area 72 has buffers (10) 72-10,..., Buffers (29) 72-29 corresponding to the respective tag numbers.
[0047]
When the tag number has completed one round, old data is overwritten in each buffer on the dual port RAM 7. Further, in order to facilitate tag search in the dual port RAM 7, tag numbers are collected in a tag area 71.
[0048]
Also, the address of each buffer on the dual port RAM 7 should be easily created from the tag number.
[0049]
Note that the tag number setting in the tag area 71 may set the validity indication bit of the area corresponding to the number instead of writing the tag number.
[0050]
Next, the operation of the first embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows a flowchart in the case where the first processor 1 writes to the common resource of the common memory 9 and the second processor 4 reads the same common resource of the common memory 9.
[0051]
The first processor determines the tag number to be assigned to the common resource, writes the same data as the data to be written to the common resource in the buffer corresponding to the tag number of the dual port RAM 7, and writes the tag number in the tag area 71 (step). W1).
[0052]
Each processor increments or circulates the tag number used this time at the end of access to the common resource and stores the tag number in a predetermined area (the next-time tag number storage area) such as a local RAM.
[0053]
Furthermore, the tag area 71 is checked to see if the read tag number is empty, and if the tag number already exists, the next number is checked for empty, and the first empty number is determined as the determined tag number. Good. In this case, the next tag number storage area is updated with the determined tag number.
[0054]
The first processor 1 accesses the resource management area 91 of the common memory and checks the management information of the common resource to be accessed (step W2).
[0055]
If the lock flag is off, it is turned on and the tag number is written at the same time (step W3).
[0056]
Lock flag reading determination and tag number rewriting are performed by non-divisionable access (such as check and lock) to prevent passing by the second processor lock flag access.
[0057]
The lock flag and the tag number must be written at the same time, and the tag number also serves as the lock flag. That is, when the tag number is 0, the lock flag is cleared, and when the tag number is other than 0, the lock flag is set.
[0058]
Here, the second processor accesses the management information of the same common resource, checks the management information, and if the lock flag is set (step R1 '), reads the tag number and reads the tag number of the write type (99 or 98). It is determined that the common resource data cannot be directly accessed for the (excluding tag number), and the corresponding tag number is searched in the dual port RAM 7.
[0059]
When the tag number is found, the data accompanying the tag number is read as the data of the common resource (step R8 '), and the operation of the second processor ends.
[0060]
The first processor writes data in the common resource of the common memory (step W4).
[0061]
The first processor checks the management information to determine whether the tag number of the common resource has been rewritten (step W5). If the tag number has not been rewritten, the first processor clears the management information (lock flag) of the common resource in the common memory. Is also cleared (step W7), and the series of operations ends.
[0062]
Here, the management information (lock flag) is cleared by checking and clearing. That is, it is confirmed that the lock flag has not been rewritten by the check, and the clear is performed only when there is no rewrite. These operations are performed by non-divisionable access.
[0063]
If the tag number has been rewritten in step W5, the data associated with the corresponding tag number in the dual port RAM 7 is copied to the common resource of the common memory 9, and the corresponding tag number in the tag area 71 of the dual port RAM 7 is cleared (step S5). W6). Thereafter, it is confirmed that the tag number has not been rewritten further (step W5), and if not, the process proceeds to step W7.
[0064]
Even if the lock flag of the common resource to be accessed is on in step W2, the first processor rewrites the tag number of the management information of the common resource to the tag number set in the dual port RAM 7 (step W8), and operates. To end.
[0065]
FIG. 5 shows a flowchart in the case where the first processor writes to the common resource of the common memory and the second processor writes to the common resource of the common memory.
[0066]
The first processor performs the same processing as in steps W1 to W7. The second processor assigns its own tag number, writes the same data as the data to be written to the common resource in the dual port RAM 7 (step W1 '), and checks the management information (lock bit) of the common resource (step W2'). ).
[0067]
If the processing of the second processor is slightly delayed, the lock flag is on (the tag number has been set), and the tag number of the common resource is rewritten to the tag number set in the dual port RAM 7 ( Step W8 '), the operation ends.
[0068]
If the processing of the second processor is somewhat earlier, the lock flag is off, and the processing is performed in the same manner as the processing of the first processor (steps W3 to W7), and the operation ends.
[0069]
FIG. 6 shows a flowchart when the first processor reads from the common resource of the common memory and the second processor writes to the common resource of the common memory.
[0070]
The first processor accesses the resource management area 91 of the common memory, and checks management information (lock flag) of the common resource to be accessed (step R1). If the lock flag is off, the tag number assigned to this common resource is determined.
[0071]
Since this is a read access, the tag number is a read type tag number to indicate that another processor can read the common resource at the same time. For example, 99.
[0072]
The first processor sets a lock flag in the common resource of the common memory (writes the read type tag number (step R2).
[0073]
In addition, the read determination of the lock flag (step R1) and the rewriting of the tag number (step R2) are performed by non-divisionable access (check and lock, etc.) to prevent the second processor from passing the lock flag access.
[0074]
The second processor writes the data to be written to the same common resource here with its own tag number and writes it to the dual port RAM 7 (step W1 '), checks the management information, and if the lock flag is on, the data of the common resource contains Since direct access is not possible, the tag portion of the common resource is rewritten with its own tag number (step W8 '), and the operation of the second processor ends.
[0075]
The first processor reads data from the common resource of the common memory (step R3). The first processor checks whether the tag number of the common resource has been rewritten (step R4).
[0076]
If it has not been rewritten, the management information (tag number) of the common resource in the common memory is cleared (step R7), and a series of operations ends.
[0077]
Here, the management information is cleared by checking and clearing. That is, it is confirmed that the lock flag has not been rewritten by the check, and the clear is performed only when the rewrite has not been performed. These operations are performed by non-divisionable access.
[0078]
If the tag number has been rewritten, if the tag number is of the write type (step R5), the data of the dual port RAM 7 is copied to the common resource of the common memory, and the copy source tag number of the dual port RAM 7 is cleared (step R6). ).
[0079]
Returning to step R4, it is checked whether rewriting has been performed again. Then, the management information of the common resources in the common memory is cleared, and a series of operations ends.
[0080]
If the lock flag is on in step R1, the first processor reads the set tag number and determines that the tag type is the write type (the second processor is writing). The data to be read is read instead (step R8).
[0081]
FIG. 7 is a flowchart in the case where the first processor reads from the common resource of the common memory and the second processor also reads from the common resource of the common memory.
[0082]
If the lock flag is off in step R1 as in the above, the first processor performs control processing in steps R2 to R3.
[0083]
If the tag number has not been rewritten (step R4), the lock flag of the common resource is cleared (step R7).
[0084]
If the tag number has been rewritten, it is determined whether it is a write type. However, the second processor for simultaneous processing is also a read, and the operation is terminated instead of the write type (step R5).
[0085]
The second processor starts read access to the same common resource and checks management information (lock bit) (step R1 ').
[0086]
If the access is slightly delayed from the access of the first processor, the lock flag is on (the tag number is set), and the second processor reads the set tag number and determines that the read type is set ( Since the first processor reads), data is read from the common resource (step R8 '). Immediately after the determination, the tag number is updated to a read type tag number (for example, 98) for the second processor.
[0087]
If the access is slightly earlier than the access of the first processor, the lock flag is off, and the processing is performed in the same manner as in step R2 and thereafter.
[0088]
In this case, the process of the first processor is the process of step R8, but the data is read from the common resource because the set tag number is of the read type.
[0089]
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the tag number of the common resource management information does not serve as a lock flag or the like.
[0090]
The management information has a lock flag, a reading flag, a processor number, and a tag number area or bit area. Only the light type tag number is set in the tag number area.
[0091]
Each processor sets a lock flag, its own processor number, and a tag number in each area if it is not in the locked state in the write access. The data is written to the common resource, the tag number area is checked, and if the tag number is set, this is read, the data is taken out from the corresponding buffer of the dual port RAM 7, and written to the common resource. If the tag number is not set, the lock flag is turned off.
[0092]
If it is already locked, the tag number is set and the reading flag is turned off.
[0093]
Each processor sets a lock flag, its own processor number, and a reading flag in the corresponding area of the management information if the read access is not in the locked state. The data is read from the common resource, the reading flag of the management information is checked, and if it is off, the tag number is read, the data is taken out from the corresponding buffer of the dual port RAM 7, and written to the common resource.
[0094]
If the reading flag remains on, it is confirmed that the processor number has not been rewritten, and the lock flag and the reading flag are turned off.
[0095]
If the read access is already in the locked state and the reading flag is OFF, the tag number set in the tag number area is read, and the data is read from the corresponding buffer of the dual port RAM 7.
[0096]
If the reading flag is on, the processor number is rewritten to the own processor number and data is read from the common resource.
[0097]
Next, a third embodiment of the present invention will be described. In this embodiment, each processor waits without rewriting the tag number unless the tag number of the management information is 0 (lock flag off) in the write access of the common resource (step W8 is not performed).
[0098]
Therefore, since the subsequent write waits during the write or read access, there is no step W5 or W6. Also, there is no processing in step R6.
[0099]
Also, the tag area 71 on the dual port RAM 7 is not required. Each processor increments or circulates the tag number used this time at the end of the common resource access, and stores the tag number in a predetermined area (the next tag number storage area) such as a local RAM.
[0100]
The processor uses this as a read tag number when writing access to the common resource. The write data is stored in the buffer of the dual port RAM 7 at the address corresponding to the tag number. Further, an address on the dual port RAM 7 is created based on the tag number read from the management information, and data is read from the buffer.
[0101]
In the above description, two processors are used. However, the dual-port RAM 7 is a four-port memory, and is defined so that the processor to which the tag number is set can be identified, that is, the third processor and the fourth processor have 30 to 39 processors, respectively. , 40 to 49 are assigned. In this way, a multiprocessor can be configured between four processors.
[0102]
Similarly, the present invention can be applied to an N multiprocessor configuration by defining the dual port RAM 7 as an N port memory accessible from the local bus of each of N (2 or more integers) processors and defining a tag number so that the processors can be identified. Can be applied.
[0103]
【The invention's effect】
As described above, according to the present invention, when another processor accesses a common resource being accessed by a certain processor and the lock flag is set, the other processor overlaps the preceding access read if the access is a read. Reading is performed from the common resource, and if the preceding access is writing, data is read from the dual port memory (or N port memory).
[0104]
If the access is for writing, the other processor stores the identification (tag number) of the write data stored in the dual port memory in advance in the management information, and the accessing processor performs a writing process to the common resource. .
[0105]
Therefore, other processors do not need to poll for the lock flag off, so that congestion of the common bus can be prevented.
[0106]
Further, the other processor does not have to wait for the processing until the lock flag is turned off, so that it can proceed to the next processing and the processing efficiency can be improved. In addition, the processing capacity of the entire system can be improved by these.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a multiprocessor system including a method of accessing a common resource according to the present invention.
FIG. 2 is a view showing an example of contents of a common memory 9 of FIG. 1;
FIG. 3 is a view showing an example of contents of a dual port RAM 7 of FIG. 1;
FIG. 4 is a flowchart showing an operation when a first processor writes to a common resource and a second processor reads the same common resource in the first embodiment of the present invention.
FIG. 5 is a flowchart showing an operation when a first processor writes to a common resource and a second processor writes to the same common resource in the first embodiment of the present invention.
FIG. 6 is a flowchart showing an operation when a first processor reads a common resource and a second processor writes the same common resource in the first embodiment of the present invention.
FIG. 7 is a flowchart showing an operation when a first processor reads a common resource and a second processor reads the same common resource in the first embodiment of the present invention.
[Explanation of symbols]
1 First processor
2,5 Local RAM / Boot ROM
3, 6 Local bus
4 Second processor
7 Dual Port RAM
71 Tag Area
72 buffer area
72-10 buffer (10)
72-29 Buffer (29)
8 common bus
9 Common memory
91 Resource Management Area
91-0 Common resource (0) management / address information
91-m Common resource (m) management / address information
92 Common Resource Area
92-0 common resource (0)
92-m common resource (m)

Claims (14)

A method in which two processors access a common resource on a common memory through a common bus,
A dual port memory accessible by each processor through a local bus, and a common resource management storage;
A plurality of unique tag numbers used by each processor are defined except for an initial value and a plurality of predetermined values so that the processor can be identified, and a buffer corresponding to the tag number is provided on the dual port memory. And
The common resource management storage manages the tag number also serving as a lock flag of a common resource, the initial value indicating that the lock flag is off, or the plurality of predetermined values that indicate that the lock flag is on and the reading is being performed for each processor. The information is held for each common resource, the processor determines the tag number when writing to the common resource, stores the write data in advance in the buffer corresponding to the tag number of the dual port memory, and stores the management information to be accessed. Checking the initial value, that is, if the lock flag is off, updating the management information to the tag number, then writing to the common resource, and initializing the tag number of the management information, that is, means for turning off the lock flag;
At the time of reading to the common resource, the management information to be accessed is checked, and if the initial value or any predetermined value, that is, if the lock flag is off or reading is being performed, the management information is updated to its own predetermined value, and Means for reading the management information and initializing the management information if it has not been updated;
An access method to a common resource, comprising means for reading data from a buffer of the dual port memory indicated by the tag number if the tag number is set in the check. The processor, upon writing to a common resource, determines a tag number, stores write data in advance in a buffer corresponding to the tag number of the dual port memory, checks management information to be accessed, and if it is an initial value, Updates the management information to the tag number, writes to the common resource, checks the management information, and if updated to another tag number, retrieves the write data from the buffer corresponding to that tag number in the dual port memory Means for initializing the management information after writing to the common resource; and, if the check information indicates that a tag number or any predetermined value is set in the management information, that is, if the lock is on, the management information is initialized. Means for updating the write data to a tag number at the time of storage in the dual port memory;
At the time of reading to the common resource, the management information to be accessed is checked, and if it is an initial value or any one of the predetermined values, it is updated to its own predetermined value, read from the common resource, and the management information is confirmed. If it has not been updated, immediately, if it has been updated to the tag number, fetch the write data from the buffer corresponding to the tag number of the dual port memory, write it to the common resource, and initialize the management information respectively Means to
2. A method according to claim 1, further comprising means for reading data from a buffer of a dual port memory indicated by a tag number set in the management information in the check. A method in which two processors access a common resource on a common memory through a common bus,
A dual port memory accessible by each processor through a local bus, and a common resource management storage;
A plurality of unique tag numbers used by each processor are defined, and the dual port memory has a buffer corresponding to the tag number,
The common resource management storage holds management information including a lock flag, a reading flag, a processor number, and a tag number for each common resource,
When writing to the common resource, the processor determines the tag number, pre-stores the write data in the buffer corresponding to the tag number of the dual port memory, checks the access target management information, and if the lock flag is off. Means for turning on this, updating the management information as the processor number and the tag number area as the tag number, writing the common resource, and turning off the lock flag of the management information;
When reading to the common resource, the management information to be accessed is checked, and if the lock flag is off or the reading flag is on, the lock flag and the reading flag are turned on, and the management information is updated with the processor number as its own number. Means for reading from the common resource, checking the management information, and clearing the lock flag or the reading flag if the processor number is not updated;
An access method to a common resource, comprising: means for reading data from a buffer of the dual port memory indicated by the tag number of the management information if the lock flag is on and the reading flag is off in the management information check. The processor determines a tag number when writing to a common resource, pre-stores write data in a buffer corresponding to the tag number of the dual port memory, checks management information to be accessed, and determines whether a lock flag is off. If this is turned on, the processor number is set to its own number, the tag number area updates the management information as the tag number, writes to the common resource, checks the management information, and if the tag number is updated, the dual port Means for taking out write data from the corresponding buffer of the memory, writing the data to the common resource, and then turning off the lock flag;
Means for updating the tag number of the management information to the tag number at the time of storing the write data in the dual port memory and turning off the reading flag if the lock flag is on in the check,
When reading to the common resource, the management information to be accessed is checked, and if the lock flag is off or the reading flag is on, the lock flag and the reading flag are turned on, and the management information is updated with the processor number being the own number. , Read from the common resource, check the management information, immediately clear the lock flag or read flag if not updated, and if the read flag is off, the dual port memory indicated by the tag number of the management information Means for taking out write data from the buffer and writing it to the common resource and then turning off the lock flag;
4. The common resource according to claim 3, further comprising means for reading data from a buffer of the dual port memory indicated by the tag number of the management information if the lock flag is on and the reading flag is off in the management information check. Access method to. Means for the processor to store a tag number for the next use, means for making the tag number read from the storage area when writing to the common resource occurs when storing the tag number in the dual port memory, and processing of the write request 4. The method according to claim 1, further comprising means for updating the tag number of the storage area by incrementing or starting at the end and updating the tag number assigned to the own processor in numerical order. Or the access method to the common resource described in 4. The dual port memory also has a tag area for holding the number or validity display flag for each tag number,
The processor refers to the tag area to check the storage area for storing the tag number for the next time and the tag number read from the storage area when writing to the common resource occurs. Means for incrementing or circulating the storage area to update the storage area and then setting the determined tag number, and when storing the write data in the tag number corresponding buffer of the dual port memory is completed, the corresponding tag number in the tag area is validated, and the dual Means for invalidating the corresponding tag number of the tag area when the write data of the buffer corresponding to the tag number of the port memory is stored in the common resource, and incrementing or starting the tag number of the storage area at the end of the processing of the write request. 5. A method for accessing a common resource according to claim 2, further comprising means for circulating and updating the common resource. 7. The method according to claim 1, wherein the two processors are N processors, and the dual port memory is an N port memory. When writing to a common resource on a common memory accessed by two processors through a common bus, a tag number is determined, a dual port memory connected to a local bus of each processor is accessed, and write data is stored in the tag number. The management information of the common resource to be accessed is stored in advance in a corresponding buffer, and if the initial value, that is, the lock flag is off, the management information is updated to the tag number and then written to the common resource. A procedure for initializing the tag number of information, that is, for turning off the lock flag;
At the time of reading to the common resource, the management information of the common resource to be accessed is checked, and if the initial value or any predetermined value, that is, the lock flag is off or being read, the management information is updated to its own predetermined value, A procedure for reading from the common resource and initializing the management information if it has not been updated;
Reading a data from the buffer of the dual port memory indicated by the tag number if the tag number is set in the check. At the time of writing to the common resource, a tag number is determined, write data is stored in advance in a buffer corresponding to the tag number of the dual port memory, and management information of the common resource to be accessed is checked. The management information is updated to the tag number, writing to the common resource is performed, the management information is confirmed, and if the tag is updated to another tag number, the write data is read from the buffer corresponding to the tag number in the dual port memory. A procedure for extracting management information after writing the information to a common resource,
A step of updating the management information to the tag number at the time of storing the write data in the dual port memory, if the management information indicates that the management information is a tag number or any predetermined value, that is, lock-on;
At the time of reading to the common resource, the management information to be accessed is checked, and if it is an initial value or any predetermined value, it is updated to its own predetermined value, read from the common resource, and the management information is updated. Confirm, if not updated immediately, if it has been updated to the tag number, fetch the write data from the buffer corresponding to the tag number in the dual port memory, write it to the common resource, and initialize the management information respectively. 9. The method according to claim 8, further comprising: a step of reading data from a buffer of the dual port memory indicated by the tag number set in the management information in the check if the tag number is set in the check. Access program. When writing to a common resource on a common memory accessed by two processors through a common bus, a tag number is determined, a dual port memory connected to a local bus of each processor is accessed, and write data is stored in the tag number. The management information to be accessed is stored in advance in a corresponding buffer, and the management information to be accessed is checked. If the lock flag is off, this is turned on, the processor number is updated to the own number, the tag number area is updated as the tag number, and the management information is updated. To write to the server and turn off the lock flag of the management information;
When reading to the common resource, the management information to be accessed is checked, and if the lock flag is off or the reading flag is on, the lock flag and the reading flag are turned on, and the management information is updated with the processor number as its own number. A step of reading from the common resource, checking the management information, and clearing the lock flag or the reading flag if the processor number is not updated;
A program for accessing a common resource, comprising a step of reading data from a buffer of a dual port memory indicated by a tag number of the management information if the lock flag is on and the reading flag is off in the management information check. When writing to the common resource, a tag number is determined, write data is stored in advance in a buffer corresponding to the tag number of the dual port memory, access target management information is checked, and if the lock flag is off, Is turned on, the processor number is set to its own number, the tag number area updates the management information as the tag number, writes to the common resource, checks the management information, and if the tag number is updated, supports the dual port memory A procedure for taking out write data from the buffer, writing to the common resource, and then turning off the lock flag;
A step of updating the tag number of the management information to the tag number when the write data is stored in the dual port memory and turning off the reading flag if the lock flag is on in the check;
At the time of reading to the common resource, the management information to be accessed is checked, and if the lock flag is off or the reading flag is on, the lock flag and the reading flag are turned on, and the processor number is updated as the own number as the processor number. Then, read from the common resource, check the management information, and immediately clear the lock flag or reading flag if it is not updated. If the reading flag is off, specify the dual port indicated by the tag number of the management information. A procedure for taking out write data from a memory buffer, writing the data to a common resource, and then turning off a lock flag;
11. The common resource according to claim 10, further comprising a step of reading data from a buffer of the dual port memory indicated by the tag number of the management information if the lock flag is on and the reading flag is off in the management information check. Access program to. At the time of writing to the common resource, the tag number read from the tag number storage area for the next time is used as the tag number at the time of storage in the dual port memory. 12. The access to the common resource according to claim 8, further comprising a procedure of updating the value by incrementing or starting from the starting value, and circulating the tag numbers assigned to the own processor in numerical order. program. At the time of writing to the common resource, the vacancy of the tag number read from the next-use tag number storage area is checked by referring to the tag number management area on the dual port memory. And circulating and updating the storage area, and then setting the determined tag number, and when the write data storage in the tag number corresponding buffer of the dual port memory is completed, the corresponding tag number in the tag number management area is validated. When the write data of the buffer corresponding to the tag number of the dual port memory is stored in the common resource, the corresponding tag number in the tag number management area is invalidated, and the next tag number storage area is stored when the processing of the write request is completed. 12. The method according to claim 9, further comprising a step of updating the number of the common resource by incrementing or starting the number. It is programmed. 2. The method according to claim 1, wherein the common resource is a common resource on a common memory accessed by N processors through a common bus, and the dual port memory is an N port memory connected to a local bus of the N processors. 14. A program for accessing a common resource according to any one of 8 to 13.

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