JP2013090200A - Memory management method of communication device, communication device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a memory management method in which a basic size of a logical memory is determined, a logic memory size is managed at a fixed length, and memory utilization efficiency is high, in memory management.SOLUTION: A basic size of a logical memory is determined on the basis of a communication method, the logical memory of the basic size is set at a memory, and data received or data to be sent is stored in the logical memory.

Description

  The present invention relates to a memory management method in a communication device.

  In communication processing, when data required by another device is transmitted to another device, the processing required for the communication processing is roughly divided into the following three. First, data to be transmitted is received from the application of the own device. Second, protocol processing such as header addition necessary for communication is performed on the data. Third, data with a header, that is, a packet is transmitted to a communication interface with another device.

  In the communication process, when data required by the own device is received from another device, the following three processes are similarly performed. First, a packet is received from a communication interface with another device. Second, the protocol processing necessary for communication is canceled, and the application of the own device that needs the data included in the packet is specified. Third, the data extracted from the packet is transmitted to the specified application of the own device.

  Thus, in communication processing, data to be transmitted / received moves between an application processing unit, a communication processing unit, and an interface processing unit. Furthermore, depending on the complexity of the protocol, there may be cases where memory copy processing such as data movement and connection is required. Therefore, an efficient method for storing data in the memory leads to an improvement in communication processing efficiency. For example, Linux (registered trademark) implements a memory management method called sk_buff. Furthermore, there are the following prior arts in the memory management method.

  For example, there is a packet memory unit that has a plurality of buffers and stores data packets in one or a plurality of buffers as required by the length of each data packet (Patent Document 1). First, there is a method in which a packet is analyzed by a reception buffer, and second, data is transferred by performing address conversion on address information of a user buffer shared in advance by an application and a communication processing unit (Patent Document 2). ). Further, in communication processing having two transfer modes, there is a method of performing data transfer by arranging an independent DMA controller, header memory, and payload memory, respectively (Patent Document 3).

JP-A-4-336729 JP-A-7-78112 Japanese Patent Laid-Open No. 2005-137022

  Processing efficiency can be improved by performing memory management that treats a memory used for communication as a plurality of logical memories. In this case, the memory management is easy if the logical memory size is fixed. However, if the data to be stored is divided by using a small value for the fixed length, a process of connecting the divided data occurs, which causes a decrease in throughput. In addition, when a large value is used for the fixed length, the memory utilization efficiency may deteriorate.

  The present invention has been made in view of the above-mentioned problems, and a predetermined length of a logical memory size suitable for communication is set in a memory used for communication to reduce throughput and memory utilization efficiency. An object of the present invention is to provide a memory management method for preventing communication processing.

  In order to solve the above problems, a memory management method in a communication device including a memory for storing received data or data requested to be transmitted according to the present invention is based on a basic size of a logical memory based on a communication method notified at the start of communication. , Determining the basic size logical memory in the memory, and storing received data or data requested to be transmitted in the logical memory.

  Provided is a memory management method in communication processing in which a predetermined length of a logical memory suitable for communication is set in a memory used for communication to prevent a decrease in throughput and a deterioration in memory utilization efficiency.

The system structural example which can apply this invention. 1 is a block diagram of a communication control apparatus according to Embodiment 1. FIG. FIG. 3 is a functional block diagram of a communication control unit according to the first embodiment. The memory structure of the main memory part which concerns on embodiment. 5 is a flowchart of memory management processing of the communication control unit according to the first embodiment. Example of received continuous packets. The data storage state of the memory which concerns on embodiment. 5 is a flowchart showing processing of a communication control unit according to the first embodiment. The data storage state at the time of the data transmission which concerns on embodiment. FIG. 9 is a functional block diagram of a communication control unit according to the second embodiment. The flowchart showing the memory management process of a communication control part. FIG. 9 is a block diagram of a communication control device according to a third embodiment. FIG. 10 is a functional block diagram of a communication control unit in the third embodiment. FIG. 10 is a data flow diagram at the time of reception between modules in the third embodiment. FIG. 10 is a data flow diagram at the time of transmission between modules in the third embodiment.

  A system according to the present embodiment will be described with reference to FIG. The electronic device 101 is an electronic device that houses the communication control device 103 and the main control device 102. The main control device 102 is a device for controlling the application of the electronic device 101. The main control device executes an application such as display if the electronic device 101 is a television, for example, printing if it is a printer, and imaging if it is a camera.

The communication control device 103 executes processing related to communication of the electronic device 101. The communication control apparatus 103 will be described as an example where wireless communication can be used. An antenna 104 is provided as an external interface for wireless communication. The electronic device 101 communicates with the wireless communication device 106 via the space 105.
The internal configuration of the electronic apparatus 101 according to the first embodiment will be described with reference to FIG.

  The electronic device 101 includes a main storage unit 201 that can be accessed from the main control device 102 and the communication control device 103, respectively. The main storage unit 201 is logically divided into a user buffer area mainly used by the main controller 102 and a communication buffer area for communication mainly used by the communication control unit 203. Among these, this embodiment is applied to the memory management method for the communication buffer area. The main controller 102 arranges data to be transmitted to the communication partner in the user buffer area of the main storage unit 201. The communication control apparatus 103 copies the data arranged in the user buffer area once as transmission data to the communication buffer area, and then performs predetermined protocol processing to convert it into packet data, which is transmitted to the communication partner. Further, the communication control device 103 stores the data received from the wireless communication device 106 once as received data in the communication buffer area, and after the communication control device 103 performs predetermined protocol processing on the received data, the necessary data is stored. Only copy to user buffer area. Thereafter, the communication control device 103 notifies the main control device 102 of data reception.

  The main control device 102, the communication control device 103, and the main storage unit 201 are connected by a main bus 202. The communication control unit 203 monitors and controls the state of the communication control apparatus 103 as a whole. Detailed operation of the communication control unit 203 will be described later. Various modules existing in the communication control device 103 are connected by a local bus 204. The auxiliary storage unit 205 is used as a work memory necessary for the communication control device to execute various processes.

  The wireless communication unit 206 executes medium access control and processing related to the physical layer, which are necessary for executing wireless communication with a communication partner. The wireless communication unit 206 operates based on the control information from the communication control unit 203. When the state of the wireless communication unit 206 changes, notification is performed by transmitting an interrupt signal 209 to the communication control unit 203.

  An interrupt signal line 207 is connected from the communication control unit 203 to the main control device 102. The communication control unit 203 notifies the main control device 102 through the interrupt signal line 207 when the set command is completed or when an error that cannot be processed by the communication control unit 203 occurs.

  An interrupt signal line 208 is connected from the main control device 102 to the communication control unit 203. The main control device 102 asserts an interrupt signal on the interrupt signal line 208 when it is desired to set an instruction to the communication control unit 203.

  An interrupt signal line 209 is connected from the wireless communication unit 206 to the communication control unit 203. The interrupt signal line 209 is used when the wireless communication unit 206 receives data from the outside, or when an interrupt signal is asserted to the communication control unit 203 when an abnormality is detected.

  The main storage unit 201 and the auxiliary storage unit 205 may be set to the same storage device, but may be different storage devices. For example, the main storage unit 201 may be a DRAM provided outside the LSI, and the auxiliary storage unit 205 may be an on-chip RAM provided inside the LSI.

Next, the detailed configuration and operation of the communication control unit 203 will be described with reference to FIG. The command processing unit 301 analyzes various commands received from the main controller 102 and determines what processing should be performed based on the analysis result.
The communication upper layer processing unit 302 processes a protocol that is an upper layer than the transport layer (fourth layer) in the OSI reference model.
The communication protocol processing unit 303 executes processing of protocols corresponding to the transport layer (fourth layer) and the network layer (third layer) in the OSI reference model.
The wireless control unit 304 performs initial setting of the wireless communication unit 206 and issues various commands.
The memory management unit 305 will be described later.

  In the present embodiment, the state detection unit 306 detects the state by receiving interrupt signals from the wireless communication unit 206 and the main control device 102. In addition, it can also comprise so that a state may be detected without using an interruption signal. As such a configuration, for example, registers indicating the states of the wireless communication unit 206 and the main controller 102 are prepared. The state detection unit 306 may execute processing for monitoring this register regularly or irregularly. The state detection may be performed by any of the above methods.

  The notification unit 307 notifies the main control device 102 that there is notification information when the communication control device 103 wants to transmit various types of information. At this time, notification is performed using the interrupt signal line 207 from the communication control unit 203 to the main control device 102. However, depending on the configuration of the main controller 102, an interrupt signal line is not necessarily required. As described in the state detection unit 306, when the main control device 102 performs an operation of checking the state of the communication control unit 203 regularly or irregularly, no interruption is necessary. The notification information may be notified by any of the above methods.

  The local bus connection unit 308 performs an operation according to the protocol of the local bus and is used to access various functional units in the communication control device 103. Note that the communication control unit 203 may be configured to be accessible from various functional units in the communication control apparatus 103.

  The main bus connection unit 309 performs an operation in accordance with the main bus protocol and is used to access various function units outside the communication control device 103. Note that the communication control unit 203 may be configured to be accessible from various function units outside the communication control apparatus 103.

  For example, when using the radio and browsing the Web, the layers must be connected to each other such as the network layer, the transport layer, and the upper layer from the wireless connection. The connection state monitoring unit 310 has a function of monitoring the connection protocol and connection state in each layer as in the above example.

  The memory management unit 305 will be described with reference to FIG. As described above, the main storage unit 201 includes the user buffer area 401 and the communication buffer area 402. In the memory management method according to the present embodiment, the communication buffer area is handled as a plurality of logical memories logically divided in units of the basic memory size 403. The memory management unit 305 manages the maximum number of logical memories, the size of each logical memory, and the correspondence between the ID and the physical address when an ID is assigned to each logical memory. The memory management unit 305 includes a management information table for memory management, and manages a state 404 (used) and a state 405 (free) in which the logical memory is used. When the communication control unit 203 executes various processes and needs memory, it acquires the required number of logical memories from the free logical memory, changes them to the management information table as used, and then uses them. Start. When the use of the logical memory is finished, the data in the used logical memory is erased as necessary, and is re-registered in the management information table as an empty logical memory. The management information table of the logical memory may be in the auxiliary storage unit 205 or the main storage unit 201. It is desirable that the memory management unit 305 can update the management information table.

  Further, it is desirable that the memory management unit 305 also monitors the usage rate of the logical memory. The usage rate of the logical memory may be calculated based on the size of the communication buffer area 402 and the effective data size actually stored in the communication buffer area 402, or the total number of logical memories and the number of used logical memories It may be calculated based on the original.

  Next, a processing procedure when the communication control unit 203 continuously receives communication packets will be described in detail with reference to FIG. An example of communication packets that arrive continuously is shown in FIG.

  The communication packet includes a header part 601 and a data part 602 attached to each packet. The header portion 601 includes a destination address (DA) 603, a transmission source address (SA) 604, and a packet length (Length) 605 indicating the data size of the data portion.

  In the present embodiment, an operation when receiving the above-described continuous communication packets will be described. First, before wireless communication is established, it waits for the communication method to be used to be notified from the main control device 102 to the communication control unit 203 of the communication control device 103 (steps 502 and 503). When the communication method is notified, the communication control unit 203 determines the maximum packet length in one packet of the communication method from the notified communication method, and based on the result, the memory management unit 305 determines the basic memory size to be used. Determine (step 504). For example, in the case of a wireless LAN using Ethernet II (registered trademark), the MTU of Ethernet II (registered trademark) is determined to be 1500 bytes. Therefore, the basic memory size is set larger than 1500 bytes. For example, when the minimum unit of the basic memory size is 128 bytes, a size exceeding 128 bytes by multiplying 128 bytes by an integer, for example, 1536 bytes is determined as the basic memory size. If the basic memory size needs to be changed, the basic memory size can be changed (steps 505 and 506). An example of changing the basic memory size will be described in a second embodiment to be described later.

  Next, when the wireless communication is not established, the wireless communication is established (steps 507 and 508), the data is received from the antenna 104, and the received data is taken into the memory inside the wireless communication unit 206. The communication control unit 203 waits for the interrupt signal to be asserted (step 509). The wireless communication unit 206 that has received the data asserts an interrupt signal to the communication control unit 203 using the interrupt signal line 209. The communication control unit 203 that has detected the interrupt signal makes an inquiry to the wireless communication unit 206 in order to identify the cause of the interrupt (steps 509 and 510). If it is determined from the inquiry result that the notification is a reception notification, the communication control unit 203 starts capturing the received data. Next, it is determined whether the packets are stored separately in the basic size logical memory or not stored separately (step 511). This determination (ON / OFF) will be described later.

  Hereinafter, a case where data is separated and stored in the basic size logical memory (when ON is determined in step 511) will be described. First, copying of the header portion 601 of the first packet received in the auxiliary storage unit 205 is started (steps 512 and 513). When the copying of the header portion 601 is completed, the length 605 of the header portion 601 is referred to (step 514), and the necessary memory size for taking in the data portion 602 of the first packet is calculated based on the reference result (step 515). The basic memory size used in the memory management unit 305 is compared with the required memory size, and the number of logical memories required for storing the first packet is calculated (step 516). Then, the required number of logical memories are acquired by changing the required number from the free logical memory to used (step 517). Normally, since the basic memory size is determined in step 504 or 506, one data packet should fit in one logical memory, but when receiving an unexpectedly long packet or the like Receive using a plurality of logical memories.

  First, the data of the header section 601 in the auxiliary storage section 205 is copied to the logical memory of the main storage section that has been acquired (steps 518 and 519). Subsequently, the data unit 602 is read from the wireless communication unit 206 and copied to the acquired logical memory (steps 520 and 521). When all the first packets are taken into the logical memory, reception of the header portion 601 in the second packet is started next. Again, the header portion 601 of the second packet is stored in the auxiliary storage unit 205. The copy process is repeated until the second and third packets are all processed in the same manner (step 522). In the case of this example, the packet is finally received and stored in the main storage unit 201 as shown in FIG.

  Here, the storage in the main storage unit 201 may be only the data unit 602 as shown in FIG. Data may be stored in the communication buffer area in a manner convenient for the mounted communication protocol processing unit 303 to process data.

  Next, packet storage when packet separation is off, as described in step 511 above, will be described with reference to FIG. Also in this case, a memory having a size necessary for receiving the packet is acquired (step 524), and the packets are sequentially stored in the acquired memory. At that time, the basic memory size of the logical memory is not used and the packets are packed and stored (steps 525 and 526). FIG. 7 (c) shows a state in which the reception function for separating and storing packets is turned off (not separated). That is, since packets can be placed without being divided for each logical memory, when considering the memory utilization efficiency, the memory utilization efficiency can be increased as compared with the method of separating packets for each logical memory of the basic size. Therefore, in an environment where packet loss frequently occurs due to memory depletion, it may be possible to suppress the occurrence of packet loss by turning off the reception function that separates and stores packets in logical memory. Therefore, it is preferable to include a mechanism capable of turning on / off the packet separation / reception function according to the present embodiment.

  How to turn on / off will be described below with reference to FIG. When communication is started, initial setting is first performed (steps 527 and 528). In the initial setting, a threshold is set for the usage rate of the logical memory. Based on this threshold, the packet separation / reception function is turned on / off. This threshold value may be set in advance by the memory management unit 305 or may be set in accordance with a command from the main controller 102. Next, the memory management unit 305 calculates the usage rate of the logical memory (step 529). On / Off of the packet separation / reception function is determined based on the calculation result and the threshold of the usage rate (steps 530, 531 and 532). For example, if the calculated memory usage rate is equal to or greater than the threshold, the packet separation reception function is turned off, and if it is less than the threshold, the packet separation reception function is turned on. The flow related to the determination (steps 529 to 532) is continuously executed until the communication is completed (step 533).

  Next, a memory management method performed by the communication control apparatus 103 when the main control apparatus 102 transmits data to another device will be described with reference to FIG. First, FIG. 8 (a) will be described. First, a communication start request using a predetermined communication method is transmitted from the main control device 102 to the communication control device 103. Then, the communication control apparatus 103 performs connection processing according to the communication format and establishes communication (steps 802 to 804). Further, the communication control apparatus 103 determines the basic memory size from the data size used for the communication method (step 805). For example, when using a wireless LAN based on the previous Ethernet II (registered trademark), 1536 bytes is used as the basic memory size in the previous procedure. If there is a request for changing the basic memory size, the basic memory size is changed according to the request (steps 806 and 807). This will be described later.

  Next, the communication control device 103 receives data that is actually desired to be transferred from the main storage device. For example, the main controller 102 prepares data to be transmitted to the user buffer area, and notifies the communication control unit 203 of the start address and the data size stored in the user buffer area. Upon receiving the notification, the communication control unit 203 determines the basic copy size to be copied at one time based on the communication method used for communication when copying data to the communication buffer area managed by the communication control unit 203. (Steps 808, 809). For example, when wireless communication using TCP / IP is performed, if there are no options in the TCP header / IP header, the maximum payload size of 1460 bytes of TCP is determined as one basic copy size. In communication using encryption / authentication, for example, communication using the IPsec protocol may use AH (Authentification Header) or ESP (Encapsulation Security Payload). In this case, an AH header or ESP header is added to the TCP header or IP header. As a result, the size at which data received from the main controller 102 can be transmitted in one packet decreases. Therefore, the basic copy size of the data is determined to be a numerical value obtained by reducing the header size to be added from the maximum data size used in the communication method.

  After determining the basic copy size, the basic copy size data is copied from the user buffer area to one logical memory in the communication buffer area (steps 810 and 811). The state of the main storage unit 201 at this time is shown in FIG. When copying data of this basic copy size, copying may be performed from the beginning of the logical memory as shown in FIG. In this case, the header part may be generated in the logical memory, or may be generated in the auxiliary storage unit 205. When a header is also generated in the logical memory, the data may be copied by moving the offset size corresponding to the header size to be added later from the start address of the logical memory as shown in FIG. 9B. Further, user data may be stored in a logical memory, and a header may be added at the time of transmission. Thus, by copying user data to the logical memory in a form commensurate with the communication packet size, when it is confirmed that the communication packet has been received by another device, the corresponding logical memory can be released immediately. . Thereby, improvement of memory utilization is realized. Thereafter, steps 810 and 811 are repeated until copying of user data placed in all user buffer areas is completed (step 812).

  The size of user data requested to be transmitted may be much larger than the packet length that can be used in the communication method. In this case, copying may be performed after dividing user data into logical blocks without starting copying immediately from user data to the communication packet size. The process is shown in FIG. 8 (b). The difference from the process of FIG. 8A is that a block size and block position determination process (step 814) for cutting into blocks is included, and that block copy end confirmation (step 815) is entered. As shown in FIG. 9 (c), the user data is divided into a predetermined block size (step 814), and copying for each block (step 810) is continued until the data of the block ends (step 811).

  Further, apart from the basic memory size at the time of the reception process of the communication control apparatus 103 described above, a basic memory size at the time of the transmission process of the communication control apparatus 103 may be prepared and used. For example, when the main control device 102 receives data in communication using TCP / IP with another device, the communication control device 103 performs TCP ACK transmission as a main transmission process. In this case, the basic memory size used for transmission by the communication control apparatus 103 can be made smaller than the basic memory size for reception, and the memory utilization efficiency can be increased.

If communication is not established, the basic memory size may be changed based on the MTU used for the established communication method after communication is established (step 508).
In the second embodiment, a method for changing the basic memory size used in the memory management unit 305 by training the communication state will be described. The change from the first embodiment is the configuration of the communication control unit. The communication control unit 213 according to the second embodiment will be described with reference to FIG.

  A communication state monitoring unit 311 and a timer unit 312 are added to the communication control unit 213. The communication state monitoring unit 311 monitors the size of the packet received from the external device. The timer unit 312 performs time management.

  A processing procedure of the communication control unit 213 when the main control apparatus 102 receives data from another device will be described with reference to FIG. FIG. 11 (a) is a flowchart showing a part of the processing of the communication control unit 213. Note that there is no change in that the communication control unit 213 performs a process of storing received data in the logical memory as in the process of FIG. Further, the communication control unit 213 also performs the process shown in FIG. 11A in parallel with the process of FIG. First, the communication control unit 213 sets an interval for performing processing using the timer unit 312 so that processing can be executed at predetermined intervals (step 1102). Next, communication state monitoring is started by the communication state monitoring unit 311 (step 1103). Here, the communication state monitoring unit 311 performs statistics on the size of the received packet. For example, the value of Length included in the header portion is statistically analyzed (step 1104). As soon as the timer expires, the statistics are finished (steps 1105 and 1106). Based on the result of the statistics, the next basic memory size is determined (step 1107). In this determination, for example, the basic memory size may be determined in accordance with the largest received packet, or the size of the packet having the largest received packet ratio may be determined as the basic memory size. Finally, the communication control unit 213 requests the memory management unit 305 to set the determined basic memory size (1108). It should be noted that the timing for changing the basic memory size may be such that the processing in the communication control unit 203 of the already received packet is once completed. The basic size may be changed at the timings of steps 505 and 506 shown in FIG.

  As a result, the basic memory size can be changed to a size suitable for the reception size, so that the memory usage efficiency can be improved, and packet loss due to sudden memory depletion caused by fluctuations in communication status can be reduced. Become.

  Next, a processing procedure of the communication control unit 213 when the main control apparatus 102 transmits data to another device will be described. In the first embodiment, the method for determining the basic memory size according to the communication method at the start of communication has been described. This method is a method for changing the basic memory size when the basic memory size determined first is not necessarily efficient. The method is shown in FIG. 11 (b). Note that there is no change in that the communication control unit 213 also performs the normal processing shown in FIG. The communication control unit 213 performs the process of changing the basic memory size shown in FIG. 11B in parallel with the process of FIG. 8 or in time division. First, the communication control unit 213 sets an interval using the timer unit 312 so that the process can be executed at a predetermined interval (step 1202). Next, communication state monitoring is started by the communication state monitoring unit 311 (step 1203). Here, every time transmission is performed, the data size notified to the communication control unit 213 as user data from the main control device 102 is statistics (step 1204). For example, in the case of communication using sockets, the data size may be statistics for each socket ID. As soon as the timer expires, the statistics are finished (steps 1205 and 1206). Based on the statistical result, the next basic memory size is determined (step 1207). Finally, the memory management unit 305 is requested to set the determined basic memory size (1208). Note that the timing for changing the basic memory size is preferably a state in which, for example, processing of a transmission packet stored in the logical memory is once completed. In the case of transmission, the basic size is determined by the MTU in advance. When a size larger than the MTU is notified to the communication control unit 213 as user data, the basic size cannot be changed because the size cannot be basically made larger than the MTU. As a result, the basic memory size corresponding to the transmission size can be appropriately selected, so that the memory utilization efficiency can be improved.

  In the third embodiment, a method for realizing memory management in a form suitable for the case where DMA (Direct Memory Access) is used for storing data in the logical memory or reading data from the logical memory will be described. First, the part concerning Embodiment 3 is demonstrated about the communication control apparatus 250 using FIG. A difference in configuration between the communication control unit 223 of the present embodiment and the communication control units 203 and 213 of the other embodiments will be described later.

  The memory management unit 251 takes part of the processing of the memory management unit incorporated in the communication control units 203 and 213. In addition, control information can be directly exchanged with a DMA unit 252 described later. The DMA unit 252 is responsible for data transfer between the auxiliary storage unit 205 and both types of storage units of the main storage unit 201 and various modules. The DMA unit 252 has a function of performing a simple comparison / analysis process on data flowing on the DMA bus 254 described later. The DMA unit 252 includes a primary storage unit 255.

  The interrupt signal line 253 is a signal line for notifying the interrupt from the DMA unit 252 to the communication control unit 223. This is used to notify the communication control unit 223 when the processing of the DMA unit 252 is completed or when an error occurs. The DMA bus 254 is a bus used for data transfer using the DMA unit 252 between the wireless communication unit 206 and the auxiliary storage unit 205 or the main storage unit 201.

  Next, the part which concerns on Embodiment 3 is demonstrated about the communication control part 223 using FIG. The DMA control unit 313 controls the DMA unit 252. The memory management function control unit 314 controls the memory management unit 251. The difference in configuration between the state detection unit 306 in FIG. 13 and the state detection unit 306 in FIG. 3 is that the state detection unit 306 in FIG. 13 also detects the state of the DMA unit 252.

  Next, data and control flow inside the communication control device 250 when the communication control device 250 receives continuous packets from other devices will be described with reference to FIG. An example of packets that are continuously received is the same as that shown in FIG. First, the wireless communication unit 206 receives continuous packets via the antenna 104. Then, the wireless communication unit 206 asserts an interrupt signal to the communication control unit 223 (1501). The communication control unit 223 that has detected the interruption makes an inquiry to the wireless communication unit 206 in order to confirm the cause of the interruption (1502). The communication control unit 223 found to be the data reception notification sets a data reception command to the DMA unit 252 (1503). Here, the instruction set in the DMA unit 252 includes address information of the wireless communication unit 206. Further, if the data size of the sum of all the packets received by the wireless communication unit 206 is known in advance, it may be notified to the DMA unit 252.

  The DMA unit 252 that has received the data reception command starts reading the received data from the wireless communication unit 206 by DMA (1504). First, the header part of the packet 1 is transferred by DMA (1505) and stored in a primary storage area inside the DMA part 252 (1506). The DMA unit 252 that has acquired the header part analyzes the Length (605) (1507), calculates the required logical memory size, and transmits a request to acquire the logical memory for the required size to the memory management unit 251 (1508). ). Upon receipt of the request, the memory management unit 251 returns a list including the physical address and size of the logical memory corresponding to the requested size from the list of free logical memory in the main storage unit 201 managed by the memory management unit 251 (1509). If the correspondence between the ID number of the logical memory and the physical address can be shared between the modules in advance, the method of returning the ID may be used. Here, the memory management unit 251 updates the information that the logical memory provided to the DMA unit 252 has been used. The DMA unit 252 that has received information on the usable logical memory sets the logical memory in the main storage unit 201 as a transfer destination, and transfers data by DMA transfer (1510, 1511). At this time, the header information from the header part already in the primary storage unit 255 may be transferred to the logical memory, or the newly read data part may be transferred to the logical memory.

  The DMA unit 252 that has transferred all the data of the packet 1 to the logical memory confirms the bus response from the wireless communication unit 206 to determine whether the received data still remains. If the received data remains, the processing 1503 to 1511 is repeated until the packets 2 and 3 and all the received data are stored in the logical memory. Note that if the communication control unit 223 notifies the total data size of all packets in step 1503, the bus response confirmation from the wireless communication unit 206 can be made unnecessary. In this case, data may be transferred by repeating processing 1503 to processing 1511 until the data transferred from the wireless communication unit 206 reaches the notified total data size. When all the packets are stored in the logical memory, the DMA unit 252 notifies the end of the data transfer by asserting an interrupt signal to the communication control unit 223 (1512). The communication control unit 223 notified of the end of the data transfer confirms the end of the data transfer with the DMA unit, and if necessary, determines what number of the packet is stored in which logical memory, the DMA unit 252 or the memory management Contact Part 251 (1514). By this inquiry, information necessary for the subsequent process is acquired (1515).

  Next, data and control flow inside the communication control device 250 using DMA transfer when the main control device 102 transmits data to other devices will be described with reference to FIG. It is assumed that settings necessary for communication are performed in advance. First, main controller 102 places user data to be transmitted in the user buffer area. Then, an interrupt signal for a transmission request is asserted to the communication control unit 223 (1601). At this time, the communication control unit 223 is notified of the address where the user data is placed and the size of the user data. Upon receiving the transmission request, the communication control unit 223 divides the user data into blocks as shown in FIG. 9 (c), and further divides the block data divided into blocks into units of packets and stores them in the logical memory. Store it. First, the position to be cut out in block units is determined (1602). Next, an instruction relating to DMA transfer for storing a predetermined size from the block data in the logical memory is set in the DMA unit 252 (1603). The predetermined size is, for example, a payload length that can be transmitted in one packet in the communication method to be used. The calculation in advance has been described in the first embodiment. If the DMA unit 252 accepts a plurality of transfer instructions at once, the instructions may be set so that all user data can be transferred at one time (1612).

  When the setting is completed for all DMA transfers, a transfer start request is transmitted to the DMA unit 252 (1604). The DMA unit 252 that has received the command transmits a logical memory acquisition request to the memory management unit 251 in order to acquire a logical memory of a size that can store the payload length that can be transmitted in one packet (1605). The memory management unit 251 extracts the required number of logical memories satisfying the required size from the free list, and notifies the DMA unit 252 of the information on the logical memory (1606). Receiving the notification, the DMA unit 252 transfers the data from the user data area to the logical memory in the communication buffer area by DMA one after another, and copies the size corresponding to the payload for one packet (1607, 1608). When the DMA transfer of the payload for one packet is completed, the communication control unit 223 is notified that the DMA storage for one packet has been completed (1609). Until all the block data is stored in the logical memory, the processing from 1605 to 1609 is continued (1613). When the end of one block data to the logical memory is completed, the process 1602 to the process 1609 are continued until all one user data is stored in the logical memory (1614). When the communication control unit 223 confirms that all packets have been sent to another device (1610), it notifies the main control device 102 of transmission completion (1611).

  The embodiment 3 has been described above. In this embodiment, memory management and data transfer are realized by the memory management unit 251 and the DMA unit 252 independent of the communication control unit 223. As a result, the processing of the communication control unit 223 is not performed in the various memory copy processes that occur inside the communication control device 250, so the communication control unit 223 performs, for example, communication header analysis / generation processing in parallel with the data transfer. Can be executed. Therefore, the communication processing efficiency can be improved.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  As described above, according to the present embodiment, by performing memory management in which physical memory is handled as a plurality of logical memories of a predetermined size, it is suitable for hardware processing, data processing can be performed easily and at high speed, and communication processing efficiency can be improved. Improvement can be achieved. Since the stream data can be directly written to the main memory by the communication control device, the processing load can be reduced. Further, by making it possible to change the size of the logical memory, it is possible to improve the memory utilization rate. By making the basic size of the memory a constant multiple of the minimum unit, it is only necessary to select from the candidate size when changing the size, and the processing is easy because it is a constant multiple of the minimum unit.

  Further, when the memory usage rate becomes high, the management by the predetermined length of the logical memory is stopped, and the data is stored in the memory so as to reduce the packet drop due to the shortage of the memory during the communication.

Claims (7)

A memory management method in a communication device including a memory for storing received data or data requested to be transmitted,
Determining a basic size of the logical memory based on the notified communication method;
Setting the basic size logical memory in the memory;
Storing received data or transmission requested data in the logical memory;
A memory management method in a communication device, comprising:   2. The method according to claim 1, wherein when the usage rate of the memory exceeds a predetermined threshold value, data is continuously stored in the memory without setting the logical memory in the memory.   The method according to claim 1 or 2, wherein the step of determining a basic size of the logical memory changes the basic size based on statistics of a size of received data or a size of transmitted data.   The method according to claim 1, wherein the basic size can be set independently for reception and transmission.   The method according to claim 1, wherein storing in the memory is performed by DMA. A communication device comprising a memory used for communication,
Means for determining the basic size of the logical memory based on the notified communication method;
Means for setting the basic size logical memory in the memory;
Means for storing received data or requested data in the logical memory;
A communication apparatus comprising:   The program for making a computer perform each process of the method described in any one of Claims 1 thru | or 5.

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