JP2000112849A - Method for attaching header to communication packet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the transfer time and to reduce the load on a CPU by reducing the copying of a memory at the time of transmitting/receiving data. SOLUTION: Continuous false virtual addresses are set up in an address conversion table 140 and a control block 150 included in a communication controller 170 provided with a DMA function as the substitutes of virtual memory addresses and the buffers of a header part 131 and a data part 123 are regarded as continued areas. Since the copying of transmitted/received data in the memory can be reduced without increasing overhead for the integration/division of the header part and the data part, the transfer time can be shortened and the load on the CPU can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a communication control device having a DMA function, and more particularly to transmission and reception of a communication packet to which a software header such as protocol information is added.

[0002]

2. Description of the Related Art When data is transferred using a communication protocol such as TCP / IP, protocol information is often attached to data as a packet header and transmitted.

According to the conventional method, in order to add a header, a header part and a data part of a packet are copied into a transmission buffer in a memory, and the packet is transmitted as one packet by designating the buffer to a communication control device. I was Also, on the receiving side, in order to divide the header part and the data part of the received packet, it is necessary to copy only the data part from the buffer written by the communication control device to the user buffer of the user application.

As a method of transmitting a packet without copying a header part and a data part, as described in JP-A-10-107855, a FIFO memory for a header part, a header size, and a buffer address for a data part are used. There is a method of storing the data size and the data size, and the communication control device reads out the data size and transmits it to the network. Further, as a method of dividing the received packet without copying, as disclosed in JP-A-06-078001 and JP-A-07-078112, the transmission side creates division information and includes it in the control information of the packet. There is a method of dividing a header part and a data part from the control information on the receiving side.

[0005]

In the method of reducing memory copying as in the prior art, the communication control device performs transmission / reception processing of a header portion and a data portion, so that the processing of the communication control device becomes complicated and overhead occurs. There is a problem of increasing.

SUMMARY OF THE INVENTION It is an object of the present invention to utilize a function of a DMA communication control device using an address conversion table to transmit and receive a memory copy without increasing the integration and division overhead of a header portion and a data portion in the communication control device. To reduce the CPU load by reducing the transfer time.

[0007]

In order to achieve the above object, a continuous pseudo virtual address is registered in the address conversion table and control block of the communication control device having the DMA function instead of the virtual memory address. Then, the buffer of the header part and the data part appears as a continuous area.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG.

This embodiment comprises a processor 160, a memory 110 and a communication controller 170 having a DMA function, and these components are connected via a system bus 180. The communication control device 170 includes a network 190
Is connected, and the communication control device 170 outputs a transmission packet to the network 190.

In the communication control device area 132, an address conversion table 140 and a control block 150 are provided. These tables are referred to from the communication control device 170 via the system bus 180. Usually, the page number 142 of the real address corresponding to the page number 141 of the virtual address is set in the address conversion table 140, and the buffer address 152, the transmission length 153, and the destination address 151 of the transmission buffer are set in the transmission control block 150. Is stored. In the address conversion table 140, a set of the page number 141 of the virtual address and the page number 142 of the real address is registered for each page. Therefore, if the virtual memories are continuous, the real memories need not be continuous.

This embodiment takes advantage of this feature and uses the header 13
The pseudo-virtual address 122 is assigned to 1 and the data section 122, so that the virtual memory appears to be continuous. However, in order to create a transmission packet using the header part and the data part as a continuous buffer, the head address of the buffer of the data part 123 must be a page boundary. Specifically, the page number 141 of the pseudo virtual address and the page number 142 of the real address corresponding to the pseudo virtual address are registered in the address conversion table 140 in page units. In the transmission control block 150 as well, a pseudo-virtual address in the header portion, which is the head address of the pseudo-virtual address, is set as the buffer address 152. The communication control device 170 searches the address conversion table 140 using the page number of the buffer address 152 set in the transmission control block 150, and acquires the page number 132 of the real address corresponding to the page number 141 of the pseudo virtual address.

Then, a real address is calculated from the page number 132 of the real address, and the transmission length 143 set in the transmission control block 140 is calculated from the real memory indicated by the address.
The data is read out, and a transmission packet is created in the transmission buffer 171 in the communication control device 170, and the network 1
Output the transmission packet to 80.

A specific example will be described with reference to FIG.
The header 131 in the OS space 130 is 0x0 of the virtual address 121
If 256 bytes from 2010F00 and the data part 123 in the user space 120 is 8192 bytes from 0x02141000 of the virtual address 121, 0x00000F00 in the header part 131 and 0x0001 in the data part 123
A continuous pseudo virtual address 122 from 0x00000F00 to 0x00003000 of 000 is allocated. In the address conversion table 140, 0x00000, 0x00001, 0x00002, which is the page number 141 of the virtual address 122, is registered. Sets 8448 bytes that are the sum of the header and data. The communication control device 170 determines the buffer address of the transmission control block 150.
The address conversion table 140 is searched for each of 0x00000, 0x00001, 0x00002, which is the page number 140 of 152, and data for a transmission length of 153 is extracted from the real memory indicated by the obtained real address, and a transmission packet is created and transmitted. .

Next, another embodiment of the present invention will be described with reference to FIG.

In the case of this embodiment, the data section is stored in the user space 22.
In order to directly store the data in the user buffer 223 of 0, the buffer 231 of the header part and the user buffer 223 are made to be continuous using the pseudo virtual address 222. Since the communication control device 270 writes the header part and the data part without distinguishing each other, the sizes of the header part and the data part need to be matched between the transmitting side and the receiving side. In addition, the user buffer 223
Must be on a page header boundary. A pseudo virtual address 222 is assigned to each of the buffer 231 for the header part and the buffer 223 for the data part, and the page number 241 of the pseudo virtual address and the page number 242 of the real address are set in the address conversion table 240 in page units. As the buffer address of the reception control block 250, a pseudo virtual address of the buffer 231 in the header, which is the head address of the pseudo virtual address, is set.

When a packet arrives, the communication control device 270
Stored the reception bucket in the reception buffer 271 and searched the address translation table 240 using the page number 251 of the buffer address 251 set in the reception control block 250, and corresponded to the page number 241 of the pseudo virtual address. Get the real address from the real address page number 232,
The contents of the received packet are written to the real memory indicated by the real address.

A specific example will be described with reference to FIG.
The header buffer 231 is 256 bytes from 0x02210F00 of the virtual address 221 and the user buffer 223 is the virtual address 221.
0x02162000 to 8192 bytes, buffer for header
A continuous pseudo virtual address 222 of 0x00000F00 is assigned to 231 and 0x0001000 is assigned to the user buffer 223. In the address conversion table 240, 0x00000, 0x00001, 0x00002 which are the pseudo virtual address page numbers 241 are registered. Is set to 8448 bytes obtained by adding the header part and the data part. The communication control device 270 includes a reception control block 250
Then, the address conversion table 240 is searched by the page number 241 of the buffer address 251 in page units, and the contents of the reception bucket are written to the real memory indicated by the real address obtained from the page number 242 of the real address.

The data flow during transmission will be described with reference to FIG. The user data 311 created by the user program 310 in the user space 350 and the packet header 321 including the protocol control information created by the communication protocol layer 320 in the OS space 360 include the network adapter 3
The packet is integrated as a transmission packet 341 by the communication control device 340 via the communication control device 30, and is output from the communication control device 340 to the network 370.

The data flow at the time of reception will be described with reference to FIG. The packet received from the network 470 is stored in the reception buffer 441, and is written in the preset user buffer 411 of the user program 410 and the buffer 421 for the packet header of the communication protocol layer.

FIG. 5 shows the transmission process of the network adapter 330 at the time of transmission, and FIG. 6 shows the transmission process of the communication control device 340. The network adapter 330 instructed by the communication protocol layer 320 to send a transmission request includes a buffer 131 in the header section.
Then, the page of the buffer 123 of the data section is fixed on the real memory (510). Then, in the address conversion table 140, the page number 141 of the pseudo virtual address assigned so that the buffer of the header section and the buffer of the data section are consecutive, and the page number 142 of the corresponding real address are registered in page units (52).
0). The transmission destination address 151, the buffer address 152, and the transmission length 153 are specified in the transmission control block 150 (530), and transmission is instructed to the communication control device 170 (540).

The communication control device 170 instructed to transmit transmits the buffer address 152 and the transmission length 15 from the transmission control block 150.
3 is obtained (610), the address conversion table 140 is searched with the page number of the buffer address 152, and the page number 142 of the real address is obtained (620). If the buffer address 152 is not on the page boundary, the offset from the page boundary to the buffer address is added to the real address calculated from the page number 142 of the obtained real address (630), and the data from the real memory indicated by the real address is added. And load
A transmission packet is created in the transmission buffer 171 of the communication control device 170 (640). This is used to send all data to transmit buffer 1.
It repeats until it is stored in 71 (650), and outputs the transmission packet created in the transmission buffer 171 to the network 180.
(660).

FIG. 7 shows a reception process of the network adapter 430 during reception, and FIG. 8 shows a reception process of the communication control device 440. The network adapter 430 instructed by the communication protocol layer 420 to receive a request fixes the header buffer 231 and the user buffer 223 in a page on the real memory (71
0). Then, in the address conversion table 240, the page number 241 of the pseudo-virtual address 222 allocated so that the header buffer 231 and the user buffer 223 are continuous, and the page number 242 of the corresponding real address are registered in page units ( 720). The buffer address 251 and the buffer length 252 are specified in the reception control block 250 (730).

The communication control device 440 that has received the packet stores the packet in the reception buffer 271 (810), obtains the buffer address 252 and the transmission length 253 from the reception control block 250 (820), and obtains the page number of the buffer address 252. The address conversion table 240 is searched by 241 to obtain the page number 242 of the real address (830). If the buffer address 252 is not on a page boundary, the offset from the page boundary to the buffer address is calculated using the page number 14 of the acquired real address.
Add to the real address calculated from 2 (840), and write the contents of the received packet to the real memory indicated by that real address
(850). This is repeated until all the contents of the received packet are written (860).

FIG. 9 shows an example of a communication packet. The packet transmitted from the communication control device 170 in the above processing takes the form of the route information 910, the destination address 920, the source address 930, the packet length 940, the header section 950, and the data section 960.

[0025]

Since the present invention is configured as described above, it is possible to reduce a memory copy when adding a header to a communication packet and a memory copy when removing the header, and to shorten a transfer time. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a transmission process according to the present invention.

FIG. 2 is a configuration diagram illustrating an embodiment of a reception process according to the present invention.

FIG. 3 is an explanatory diagram of a data flow of a transmission process.

FIG. 4 is an explanatory diagram of a data flow of a reception process.

FIG. 5 is a flowchart of a transmission process of a network adapter.

FIG. 6 is a flowchart of a transmission process of the communication control device.

FIG. 7 is a reception processing flowchart of a network adapter.

FIG. 8 is a flowchart of a reception process of the communication control device.

FIG. 9 is a diagram showing an example of a communication packet.

[Explanation of symbols]

123: Data part buffer, 131: Header part buffer, 140: Address conversion table, 150 ...
Transmission control block, 170 ... communication control device,
223: User buffer, 231: Header buffer,
240: Address conversion table, 250: Reception control block, 270: Communication control device, 310: User program, 320: Communication protocol layer, 321: User data, 322: Packet data, 330: Network adapter, 340 ...
Communication control device, 410 ... User program, 4
20: Communication protocol layer, 421: User data,
422: packet data, 430: network adapter, 440: communication control device.

Claims (2)

[Claims] In a communication control device having a DMA function, a buffer of a data portion of a packet to be transmitted and a virtual buffer are designated by designating a pseudo virtual address instead of a virtual address in an address conversion table of the communication control device. A header adding method for a communication packet, characterized in that a buffer of a header portion to be added appears to be pseudo-continuous, and is transmitted as one communication packet without memory copying. 2. A communication control apparatus having a DMA function, wherein a pseudo-virtual address is specified in place of a virtual address in an address conversion table of the communication control apparatus, so that a reception buffer of a header part and a data part is continuously connected. A communication packet header adding method, wherein only a data portion transmitted as one packet together with a header portion is directly stored in a user buffer of a user application.