JPH0744564B2 - Communication control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for managing a data buffer of a communication control device connecting a plurality of communication lines.
The present invention relates to a communication control device that can reduce the busy state of a buffer and improve the usage efficiency of a communication line.

[0002]

2. Description of the Related Art Conventionally, in this type of communication control device, a storage area for holding transmission / reception data is managed as a buffer. However, in a plurality of communication lines to be accommodated, the amount of transmitted / received data per unit time, the number of required buffers, and the length of transmitted / received data are different for each communication line. Therefore, as a general method of effectively using a buffer, a method of sharing the buffer between lines and acquiring or releasing the buffer as needed is adopted. Conventional techniques for achieving this can be classified into the following three types. Regardless of the send / receive data length, a method of deciding the buffer to a fixed length and managing only the number of buffers (fixed length buffer method) Pay attention to the longest send / receive data length handled for each communication line, and communicate by this send / receive data A method of classifying lines into several groups, determining the buffer length for each group, and managing the number of buffers for each group (buffer pool method) Dividing the storage area into small storage units without fixing the buffer length , Method of Generating Buffer of Arbitrary Length by Combination of Storage Units (Storage Unit Concatenation Method) These conventional techniques will be described with reference to FIG. In FIG. 1, reference numeral 51 is a host device such as a computer requesting communication, 2 is a host device interface unit for transmitting / receiving data to / from the host device 3, 3 is a transmission / reception control unit for executing a data communication procedure, and 7 is a partner station. Communication line for communication, 4
Is a line control table for storing line control information for each communication line 7, 1 is a storage area for temporarily holding transmission / reception data, 5 is a buffer acquisition or release at the request of the transmission / reception control unit 3, and storage area 1 A buffer management unit 6 that manages an unused area, and a line connection unit 6 that is electrically connected to the communication line 7.

FIG. 6 is a diagram showing the structure of a storage area 1 for buffer management by the fixed length buffer method. Reference numeral 61 is a buffer in which the storage area 1 is divided into fixed lengths. In the figure, the shaded portion of the buffer 61 indicates the area in use.

FIG. 7 is a diagram showing the structure of the storage area 1 for buffer management by the buffer pool method. Reference numeral 71 is a buffer obtained by dividing the storage area 1 into the length of the buffer pool 1, and 72 is a buffer obtained by dividing the storage area 1 into the length of the buffer pool 2. The buffer pool is a group in which a plurality of communication lines 7 are classified according to the length of transmission / reception data, and the length of the buffer pool is the maximum length of transmission / reception data of the communication lines 7 belonging to this buffer pool. In addition, the buffer pool can be set to an arbitrary number. In the figure, the shaded portions of the buffers 71 and 72 indicate areas in use.

FIG. 8 is a diagram showing the structure of the storage area 1 for buffer management by the storage unit connection method. Reference numeral 81 is a storage unit obtained by dividing the storage area 1 into a length smaller than the buffer length required for the entire communication control device, 82 is a data storage area for storing transmission / reception data in the storage unit 81, and 83 is a storage unit 81. Is a concatenation pointer for concatenating storage units. In the figure, the shaded portion of the storage unit indicates the storage unit in use.

FIG. 9 is a diagram showing the structure of a buffer for buffer management by the storage unit concatenation method. Reference numeral 81 is a storage unit obtained by dividing the storage area 1 into a length smaller than the buffer length required for the entire communication control device, 82 is a data storage area for storing transmission / reception data in the storage unit 81, and 83 is a storage unit 81 Is a concatenation pointer for concatenating storage units. A value indicating the own storage unit is stored in the concatenation pointer 83 of the last storage unit 81 that constitutes the buffer. In the figure, the number in [] indicates the start address of the storage unit.

Next, each method described above will be described in detail. Fixed Length Buffer Method A method of deciding the buffer to a constant length and managing only the number of buffers regardless of the transmission / reception data length will be described with reference to FIG.

The buffer management unit 5 divides the storage area 1 according to the longest data length of the transmission / reception data handled by all the communication lines 7 before starting the communication. Each divided storage area serves as a buffer 61.

The transmission / reception control unit 3, which needs a buffer for data transmission / reception, makes a buffer request to the buffer management unit 5. The buffer management unit 5 searches the storage area 1 for an unused buffer and determines that the buffer is in use to acquire the buffer. Next, the buffer management unit 5
Notifies the transmission / reception control unit 3 of the buffer address. The transmission / reception control unit 3 recognizes a storage area having a predetermined buffer length from the notified address as a use-permitted buffer. The transmission / reception control unit 3 requests the buffer management unit 5 to release the buffer when the buffer becomes unnecessary. Buffer management unit 5 requested to release the buffer
Changes the storage area having a predetermined buffer length from the release buffer address to the unused storage area.

In this method, since the buffer length is constant, the processing of the buffer management unit 5 is simple, but when the actual transmission / reception data length is shorter than the buffer length, the difference becomes an unusable area. However, since the buffer length must be equal to or longer than the transmission / reception data length in any case, the occurrence of an unusable area is unavoidable. Further, when short data is transmitted and received frequently, the use efficiency of the storage area 1 may be low, but a buffer may not be acquired. This state is remarkable in a plurality of lines having different transmission / reception data lengths. Buffer pool method Paying attention to the longest send / receive data length handled for each communication line 7, classify the communication lines 7 into several groups according to the send / receive data, determine the buffer length for each group, and determine the number of buffers for each group. The management method will be described with reference to FIG.

Before starting communication, the buffer management unit 5 obtains the required buffer length from the longest transmission / reception data for each communication line 7, and classifies the communication line 7 into several groups according to this buffer length. Next, the buffer management unit 5 divides the storage area 1 into each group. The divided area is called a buffer pool, and the buffer management unit 5
Divides each buffer pool into buffers. This state is shown in FIG. Further, the buffer management unit 5 records the identification information of the buffer pool used by each communication line 7 in the line control table 4.

The transmission / reception control unit 3, which needs a buffer for data transmission / reception, makes a buffer request to the buffer management unit 5. The buffer management unit 5 checks which communication line 7 the requested buffer is used for, searches the line control table 4 of the communication line 7, and determines from which buffer pool the buffer is acquired. After the buffer pool is determined, the buffer is acquired or released similarly to the above method.

In this method, by using the buffer pool, it is possible to reduce the difference between the actual transmission / reception data length and the buffer length generated by the above method and improve the use efficiency of the storage area 1. But with the buffer pool,
Since the number of buffers included in this buffer pool is determined before communication is started, buffers in other buffer pools are replenished to avoid buffer busy while using all buffers in one buffer pool. It is not possible to deal with it dynamically. Therefore, although it is possible to improve the usage efficiency in the buffer belonging to a certain buffer pool, the probability of buffer acquisition failure may increase in consideration of the plurality of communication lines 7. Storage unit concatenation device A method of dividing a storage area into small storage units without fixing the buffer length and generating a buffer of an arbitrary length by combining the storage units will be described below with reference to FIGS. 8 and 9. .

The buffer management unit 5 divides the storage area 1 into a length equal to or smaller than the minimum buffer required for the entire communication control device before starting communication. The divided area is called a storage unit 81, and this storage unit 81 is composed of a data storage area 82 for storing transmission / reception data and a connection pointer 83 for connecting the storage units 81 to each other.

The transmission / reception control unit 3 which needs a buffer for data transmission / reception makes a buffer request to the buffer management unit 5. The buffer management unit 5 finds a plurality of unused storage units 81 from the storage area 1 and connects the storage units 81 using the connection pointer 83. The unused storage unit 81 found at this time is in use. Unused storage units 81 until the total length of the data storage areas 82 of the connected storage units 81 becomes equal to or larger than the request buffer length.
Continue to connect. When the connection of the storage units 81 having the length equal to or larger than the requested buffer length is completed, the buffer management unit 5 notifies the transmission / reception control unit 3 of the address of the storage unit 81 at the head of the connection. The buffer recognized by the transmission / reception control unit 3 has a format as shown in FIG. When the transmission / reception control unit 3 uses the notified buffer, the transmission / reception data is delimited for each length of the data storage area 82 and stored in each storage unit 81. The transmission / reception control unit 3 requests the buffer management unit 5 to release the buffer when the buffer becomes unnecessary. The buffer management unit 5 that is requested to release the buffer traces the concatenation pointer 83 of the storage unit 81 in order from the release buffer address, and changes all of the storage units up to the last storage unit 81 from being used to being unused.

In this method, since the unusable area in the storage area 1 is less than the number of concatenated pointers 83 and one storage unit 81 per buffer,
It is possible to improve the use efficiency of the storage area 1 as compared with the above method. But 8 storage units forming one buffer
Since 1 is discontinuous, processing becomes complicated at the stage of using the buffer, and processing time also increases. (JP-A-6
(JP-A-2-177647, JP-A-3-32254)

[0017]

Generally, it is possible to improve the throughput of the communication line by improving the use efficiency of the storage area in the communication control device and continuously transmitting and receiving the data. However, the above-mentioned conventional communication control is required. In the device, buffer management for improving the use efficiency of the storage area is complicated, and there is a drawback that the processing time when using the buffer is increased.

The present invention solves such a problem, and it is an object of the present invention to provide a device capable of simplifying buffer management, shortening the processing time for using the buffer, and improving the usage efficiency. To aim.

[0019]

According to the present invention, there is provided a host device interface which is connected to a host device and a plurality of communication lines and which sends and receives data to and from the host device, and a line connection which sends and receives data to and from the communication line. Unit, a transmission / reception control unit that controls data transmission / reception of the line connection unit according to a data communication procedure, a line control table that stores control information that controls the communication line, and a data to the communication line or the host device. In a communication control device including a storage area for temporarily holding and a buffer management unit for managing an unused area of the storage area, a plurality of buffers of equal length divided inside into a plurality of buffer cells are provided in the storage area. The arranged buffer area and the buffer area that defines the buffer class by classifying the buffer area according to the size of the free area of the buffer cell. A means for selecting an optimum buffer class in accordance with a buffer request from the transmission / reception control unit, and passing a part or all of the free space to the transmission / reception control unit as a logical buffer. , Means for performing release processing in response to a logical buffer release request from the transmission / reception control unit, and causing the logical buffer to belong to an optimum buffer class according to the size of a free area in the buffer to which the logical buffer belongs.

[0020]

In the storage area, a buffer area in which a plurality of equal-length buffers whose inside is divided into a plurality of buffer cells are arranged,
A buffer class definition part that defines the buffer class by classifying this buffer area according to the free area of the buffer cell is provided, and the buffer management part stores all buffers according to the length of consecutive unused buffer cells. It is assigned to each buffer class, and when a buffer is required for data transmission / reception operations, consecutive unused buffer cells in the buffer are used as buffers.

As a result, the buffer can be managed by the free area in the buffer without extremely increasing the processing amount, and the storage area can be effectively used.

[0022]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG.
FIG. 3 is a diagram showing a configuration of a storage area in the embodiment of the present invention.

In the embodiment of the present invention, a host device interface 2 which is connected to the host device 51 and a plurality of communication lines 7 and sends and receives data to and from the host device 51, and a line connection section which sends and receives data to and from the communication line 7. 6, a transmission / reception control unit 3 that controls data transmission / reception of the line connection unit 6 according to a data communication procedure, a line control table 4 that stores control information that controls the communication line 7, and a communication line 7 or a higher-level device 51. A storage area 1 for temporarily holding data and a buffer management unit 5 for managing an unused area of the storage area 1 are provided. Further, as a feature of the present invention, the storage area 1 is divided into a plurality of buffer cells inside. Buffer 1 of equal length
A buffer area 13 in which a plurality of 4 are arranged, and a buffer class defining unit 12 that defines the buffer class by classifying the buffer area 13 according to the size of the free area of the buffer cell are provided. The optimum buffer class is selected according to the buffer request of No. 3 and a part or all of the free area is passed to the transmission / reception control unit 3 as a logical buffer, and the release processing is performed according to the logical buffer release request of the transmission / reception control unit 3. And assigning to the optimum buffer class according to the size of the free area in the buffer to which the logical buffer belongs.

FIG. 3 is a diagram showing the format of the buffer existing in the storage area in the embodiment of the present invention. 21 is the next buffer address belonging to the same buffer class, 22 is the previous buffer address belonging to the same buffer class, 23
Is a buffer cell use state management unit that is a set of flags indicating the use status of buffer cells, 24 is a buffer data unit of the set of buffer cells, and 25 is a storage unit that constitutes a logical buffer that is passed to a buffer request source. It is a buffer cell. The logical buffer is a unit for storing transmission / reception data, and its length is determined by the maximum transmission / reception data length in each communication line 7. When the transmission / reception control unit 3 transmits / receives data, the buffer management unit 5 requests not the buffer but the logical buffer. The logic buffer is composed of continuous buffer cells.

FIG. 4 is a diagram showing an example of a buffer class for the buffer management section in the embodiment of the present invention to classify and manage the buffers. 31 is a buffer class (buffer class identification number), 32 is the maximum free area length of a buffer that can belong to the buffer class, 33 is the ratio of the maximum free area length when the maximum free area length of buffer class 1 is 1. A certain free area coefficient, 34 is a buffer class header pointer that stores the address of the first buffer for connecting the buffers belonging to the buffer class, and 35 is the last buffer for connecting the buffers belonging to the buffer class. A buffer class tail pointer that stores an address. Buffer class header pointer 34,
A collection of the buffer 14 configured by the buffer class tail pointer 35, the next buffer address 21 in the buffer 14, and the previous buffer address 22 is called a buffer class loop.

FIG. 5 is a diagram showing the concept of a buffer class loop in which the buffer management unit in the embodiment of the present invention manages a buffer for each buffer class (buffer class 2).
Example). 34 is a buffer class header pointer, 21 is a next buffer address in the same buffer class loop, 23 is a buffer cell use state management unit that is a set of flags indicating the use state of buffer cells, and 24 is buffer data of a set of buffer cells. It is a department. In the figure, the arrow indicating the buffer chain indicates the forward direction, the buffer cell with the flag = 1 in the buffer cell use state indicates being in use, and the shaded buffer cell indicates an unused buffer cell.

The buffer management unit 5, before starting communication,
The storage area 1 is divided into buffers 14 as shown in FIG. The size of the buffer data section 24 of the buffer 14 shown in FIG.
Is the length required to store the longest send / receive data in. Further, the size of the buffer cell 25 of the buffer 14 shown in FIG. 3 is a length required to store the shortest transmission / reception data in all the communication lines 7 connected to the communication control device. At this time, if the length of the buffer data section 24 is an integral multiple of the length of the buffer cell 25, the use efficiency of the storage area 1 will be high. The buffer cell use state management unit 23 indicates whether each buffer cell 25 is used or not used, and its size is determined by the number of buffer cells 25 included in the buffer data unit 24.

Next, the buffer management unit 5 reads the longest transmission / reception data length for each communication line 7 from the line control table 4 and determines the buffer class 31. Here, the buffer class 31 will be described with reference to the example shown in FIG. First, θ of the buffer class 31 exists because all the buffer cells 25 of the buffer data unit 24 belong to the buffer 14 being used, and therefore the maximum free area length 32 and the free area coefficient 33 are always θ. The maximum free area length 32 of 1 of the buffer class 31 becomes the size of the buffer cell 25. This is equal to the length that the communication control device can store the shortest transmission / reception data. The free area coefficient 33 at this time is always 1. When the buffer class 31 (4 in FIG. 4) having the largest maximum free area length 32 is N, the maximum free area length 32 of N of the buffer class 31 becomes the size of the buffer data section 24. This is equal to the length that the communication control device can store the longest transmission / reception data. Buffer class 3
The maximum free area length 32 of 1 to 2 to N-1 is equal to that of each communication line 7
It may be arbitrarily determined in consideration of the longest transmission / reception data length in, but in order to simplify the processing, each free area coefficient 33
(Ratio of the maximum free area length 32 when 1 of the buffer class 31 is used as a reference) is set to be an integer.

Further, the buffer management unit 5 creates the class buffer loop shown in FIG. The class buffer loop exists corresponding to each buffer class 31. Therefore, in the case of the example shown in FIG.
Exist. The buffer 14 in the storage area 1 is always connected to one of the class buffer loops using the next buffer address 21 and the previous buffer address 22 in the buffer. Which class buffer loop is connected is determined by the continuous maximum length of the unused buffer cells 25 in the buffer 14 and the maximum free area length 32 of the buffer class 31. In the example shown in FIG. 5, the continuous maximum lengths of the unused buffer cells 25 are 512 bytes and 768 bytes, respectively.
Is. Comparing this with the maximum free area length 32 shown in FIG. 4, it corresponds to 2 of the buffer class 31 (1024 bytes or more is necessary to correspond to 3 of the buffer class 31). Therefore, the buffer shown in FIG. 5 is connected to the buffer class loop corresponding to 2 of the buffer class 31.

Since all the buffer cells 25 of all the buffers 14 are unused before the communication is started, the buffer management unit 5 sets all the buffers 14 to the buffer class loop corresponding to N of the buffer class 31 (4 in FIG. 4). Connect to.

The transmission / reception control unit 3 which has started the communication and needs the buffer requests the buffer management unit 5 for the buffer by designating the buffer length. The request buffer is called a logical buffer to distinguish it from the buffer 14 on the buffer management unit 5. The buffer management unit 5 searches which buffer class 31 the logical buffer length belongs to. When the buffer class 31 is m, it is clear from the configuration of the buffer class loop that the buffer 14 that can acquire the logical buffer is the buffer 14 connected to the buffer class loop corresponding to m to N of the buffer class 31. Is.

The buffer management unit 5 has a buffer class 31.
The buffer 14 connected to the buffer class loop corresponding to m is extracted from the buffer class loop. If there are no buffers in the buffer class loop,
The buffer class 31 is increased by 1 such as m + 1, m + 2, ... If the buffer 14 does not exist even after searching up to N of the buffer class 31, the buffer becomes busy and the transmission / reception control unit 3 is notified of acquisition failure of the logical buffer. When the buffer 14 exists, the buffer management unit 5 refers to the buffer cell usage state management unit 23, searches for a continuous unused buffer cell 25 that satisfies the logical buffer length, and logically determines the address of the first buffer cell 25. The transmission / reception control unit 3 is notified as a buffer address.

After that, the buffer management unit 5 changes the buffer cell usage state management unit 23 corresponding to the buffer cell 25 constituting the acquired logical buffer to "in use". Next, in order to return the buffer 14 to the buffer class loop, the buffer management unit 5 refers to the buffer cell usage state management unit 23 and determines from the maximum length of the continuously unused buffer cells 25 and the maximum free area length 32 of the buffer class 31. A buffer class loop that returns the buffer 14 is determined, and the buffer 14 is connected to the buffer class loop.

When an unnecessary buffer is generated, the transmission / reception control unit 3 specifies a logical buffer address and requests the buffer management unit 5 to release the buffer. The buffer management unit 5 finds which buffer 14 the logical buffer belongs to, and releases the buffer cell 25 that constitutes the logical buffer to be released.
The buffer cell use state management unit 23 corresponding to is changed from being used to being unused. Since the unused buffer cells 25 of the buffer 14 are increased by the logical buffer release process,
The buffer class 31 of the buffer is changed. This is the same processing as when returning the buffer 14 to the buffer class loop at the end of acquisition of the logical buffer.

[0035]

As described above, according to the present invention, the buffer class changing process of the buffer is added to the buffer management process, and the buffer is moved between the buffer classes to thereby prevent the occurrence of the buffer busy in the buffer class unit. In addition, the buffer (logical buffer) form seen from the buffer request source can be maintained in the same continuous storage area as in the past, and even if the unused area of the storage area where the buffer cannot be acquired is small. This has the effects of increasing the probability of acquiring a buffer, reducing the suspension of data transmission and reception due to buffer busy, and improving the utilization efficiency of communication lines.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention and a conventional example.

FIG. 2 is a diagram showing a configuration of a storage area according to an embodiment of the present invention.

FIG. 3 is a diagram showing a format of a buffer existing in a storage area according to the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a buffer class definition unit in a storage area according to the embodiment of the present invention.

FIG. 5 is a diagram showing a concept of a buffer class loop in which a buffer management unit manages a buffer for each buffer class according to an embodiment of the present invention.

FIG. 6 is a diagram showing a buffer area in a fixed length buffer system of a conventional example.

FIG. 7 is a diagram showing a buffer area in a conventional buffer pool system.

FIG. 8 is a diagram showing a buffer area in the conventional storage unit concatenation method.

FIG. 9 is a diagram showing a concept of a buffer in a conventional storage unit concatenation method.

[Explanation of symbols] 1 storage area 2 upper device interface section 3 transmission / reception control section 4 line control table 5 buffer management section 6 line connection section 7 communication line 12 buffer class definition section 13 buffer area 14, 61 buffer 21 next buffer address 22 previous Buffer address 23 Buffer cell usage status management section 24 Buffer data section 25 Buffer cell 31 Buffer class 32 Maximum free area length 33 Free area coefficient 34 Buffer class header pointer 35 Buffer class tail pointer 51 Upper device 71 Divided into buffer loop 1 length Created buffer 72 Buffer divided into buffer loop 2 length 81 Storage unit 82 Data storage area 83 Concatenated pointer

Claims (1)

[Claims] 1. A host device interface that is connected to a host device and a plurality of communication lines and that sends and receives data to and from the host device, a line connection unit that sends and receives data to and from the communication line, and according to a data communication procedure. A transmission / reception control unit that controls data transmission / reception of the line connection unit, a line control table that stores control information that controls the communication line, and a storage area that temporarily holds data to the communication line or the host device, In a communication control device including a buffer management unit that manages an unused area of a storage area, a buffer area in which a plurality of buffers of equal length divided into a plurality of buffer cells are arranged in the storage area, A buffer class definition unit that classifies an area according to the size of the empty area of the buffer cell and defines a buffer class. A means for selecting, in the buffer management unit, an optimum buffer class according to a buffer request from the transmission / reception control unit, and passing a part or all of the free space to the transmission / reception control unit as a logical buffer; And a means for performing release processing according to the logical buffer release request, and causing the logical buffer to belong to the optimum buffer class according to the size of the free area in the buffer to which the logical buffer belongs.