Patent Application
20220171725
The present invention relates to a packet processing apparatus and a packet processing method, and more particularly to a packet processing apparatus and a packet processing method for performing packet data transfer processing in a communication system.
In this packet processing apparatus, the packet transfer unit 102 performs data transfer using direct memory access (DMA) to store a packet in the packet memory 101 when triggered by arrival of the packet at the line handling unit 100 connected to the communication line (not illustrated). At the same time, the packet transfer unit 102 generates a hardware interrupt to notify a processor (not illustrated) of the packet processing apparatus that the packet has been received and issues a request to activate the reception processing unit 103.
The packet transfer unit 102 includes a descriptor 1020 which is a data structure constructed by software executed by the processor of the packet processing apparatus and a DMA controller 1021 which is hardware.
An example of
The processor sets/resets flags AF #1 to AF #N, which indicate whether or not the set addresses A #1 to A #N are valid, in the descriptor 1020. When the processor has set the flags AF #1 to AF #N to valid after setting the addresses A #1 to A #N, packets are allowed to be written to the packet memory 101.
Reception completion flags WF #1 to WF #N indicating whether or not writing of packets to the set addresses A #1 to A #N has been completed and received data sizes L #1 to L #N indicating the packet lengths of packets written to the set addresses A #1 to A #N are also set in the descriptor 1020.
When the flag AF #1 indicates that the start address is valid (yes in step S102 in
After completing writing of the packet, the DMA controller 1021 writes a received data size L #1 indicating the packet length of the nth (=1st) packet and the reception completion flag WF #1 indicating that writing of the packet has been completed to the descriptor 1020 (step S105 in
Further, the DMA controller 1021 generates a hardware interrupt to notify the processor (not illustrated) of the packet processing apparatus that writing of the packet has been completed and issues a request to activate the reception processing unit 103.
Then, the DMA controller 1021 determines whether or not the variable n is equal to N (step S106 in
Next, the activated reception processing unit 103 passes the received packet transferred to the packet memory 101 to the protocol processing unit 104. At the same time, the reception processing unit 103 secures a new area for the packet memory 101 in the memory of the packet processing apparatus in order to replenish the portion of the packet memory passed to the protocol processing unit 104.
The protocol processing unit 104 to which the received packet has been passed releases the area of the packet memory 101 when necessary protocol processing has been completed.
In the general reception processing as described above, it is known especially that when small packets arrive frequently, the number of hardware interrupts increases, such that load on the processor of the packet processing apparatus increases and the reception performance is lowered. It is also known that the reception performance is lowered due to an overhead associated with DMA transfer control because the number of times a DMA transfer is activated increases.
In order to deal with such a problem, a technique has been proposed in which a plurality of small packets are grouped into one large combination packet until a threshold set in the line handling unit is reached and the combination packet is DMA-transferred collectively to a packet memory when triggered by the size of the combination packet reaching the threshold (see Patent Literature 1).
Use of such a DMA transfer method (hereinafter referred to as collective DMA transfer) in which a plurality of small packets are transferred collectively as one combination packet can reduce the number of hardware interrupts even when small packets arrive at the packet processing apparatus and reduce the overhead of DMA transfer, enabling high-speed reception processing.
In the packet processing apparatus illustrated in
Similar to the case of
The processor presets in the descriptor 1020a start addresses AD #1 to AD #N at which to write combination packets to the packet memory 101. Usually, the number of addresses that can be set at the same time is predetermined and the order in which the addresses are used is also predetermined.
The processor sets/resets flags ADF #1 to ADF #N, which indicate whether or not the set addresses AD #1 to AD #N are valid, in the descriptor 1020a. When the processor has set the flags ADF #1 to ADF #N to valid after setting the addresses AD #1 to AD #N, combination packets are allowed to be written to the packet memory 101.
Reception completion flags WDF #1 to WDF #N indicating whether or not writing of combination packets to the set addresses AD #1 to AD #N has been completed and received data sizes LD #1 to LD #N indicating the lengths (the sums of packet lengths of packets combined) of combination packets written to the set addresses A #1 to A #N are also set in the descriptor 1020a.
When the flag ADF #1 indicates that the start address is valid (yes in step S202 in
After completing writing of the combination packet, the DMA controller 1021a writes a received data size LD #1 indicating the length of the nth (=1st) combination packet and the reception completion flag WDF #1 indicating that writing of the combination packet has been completed to the descriptor 1020a (step S205 in
Further, the DMA controller 1021a generates a hardware interrupt to notify the processor (not illustrated) of the packet processing apparatus that writing of the combination packet has been completed and issues a request to activate the reception processing unit 103.
Then, the DMA controller 1021a determines whether or not the variable n is equal to N (step S206 in
The reception processing unit 103 activated in response to an activation request from the combination packet transfer unit 102a (the DMA controller 1021a) passes the combination packet transferred to the packet memory 101 to the protocol processing unit 104.
According to the configuration illustrated in
However, in the configuration illustrated in
The restoration processing can also be realized by software of the reception processing unit 103 or the like. However, similar to the above, it is necessary to provide means for the packet combining unit 106 to notify the reception processing unit 103 of information required for the restoration processing (the number of packets combined and the size of each packet), which causes a problem of increasing the scale of hardware of the packet combining unit 106 or the like. Further, because the restoration processing is performed by software, there is more software-based processing and the load on the processor increases, and as a result, there is a problem that the improvement of reception performance by the collective DMA transfer is limited.
Similar to when the packet restoration processing is realized by hardware of the protocol processing unit 104, when the combination packet separation unit 108 is realized by hardware, it is necessary to provide means for the packet combining unit 106 to notify the combination packet separation unit 108 of information required for the restoration processing (the number of packets combined and the size of each packet), which causes a problem of increasing the scale of hardware of the packet combining unit 106 or the like.
The restoration processing can also be realized by software of the combination packet separation unit 108 or the like. However, similar to the above, it is necessary to provide means for the packet combining unit 106 to notify the combination packet separation unit 108 of information required for the restoration processing (the number of packets combined and the size of each packet), which causes a problem of increasing the scale of hardware of the packet combining unit 106 or the like. Further, because the restoration processing is performed by software, there is more software-based processing and the load on the processor increases, and as a result, there is a problem that the improvement of reception performance by the collective DMA transfer is limited.
The data combining unit 120 transfers data output by the packet processing unit 114 to the reception buffer 118 for data combining. At this time, the data combining unit 120 stores a piece of data output by the packet processing unit 114 in the reception buffer 118 such that the piece of data and pieces of data already stored in the reception buffer 118 are concatenated into one data block.
The combination data transfer unit 102b DMA-transfers the data block generated by the data combining unit 120 to the data memory 115.
The reception processing unit 117 passes the data block transferred to the data memory 115 to the combination data separation unit 108b. The combination data separation unit 108b restores a plurality of original pieces of data from the data block. The data processing unit 116 performs necessary processing on the data restored by the combination data separation unit 108b.
In the configuration illustrated in
The combination data separation unit 108b can also be realized by software, but this causes a problem that there is more software-based processing as compared to when data combining is not performed.
Further, when the entire processing of
Embodiments of the present invention have been made to solve the problems in the related scheme and it is an object of embodiments of the present invention to provide a technology that can reduce the scale of hardware required for the processing of restoring a plurality of original pieces of data from a data block into which the plurality of pieces of data have been combined in a packet processing apparatus which uses collective DMA transfer by hardware or collective writing by software and can also achieve high reception performance due to the effects of collective DMA transfer or collective writing.
A packet processing apparatus of embodiments of the present invention includes a packet processing unit configured to perform processing on a packet received from a communication line and output data that is a result of the processing, a data combining unit configured to concatenate a plurality of pieces of data output from the packet processing unit to generate a data block, a data memory configured to store data output from the packet processing unit, and a combination data transfer unit configured to DMA-transfer the data block generated by the data combining unit to the data memory or write the data block to the data memory through a processor, wherein the combination data transfer unit is configured to write information on an address in the data memory of a beginning of an individual piece of data in the data block to a descriptor that is a data area on a predetermined memory.
A packet processing apparatus of embodiments of the present invention includes a packet processing unit configured to perform processing on a packet received from a communication line and output data that is a result of the processing, a data combining unit configured to concatenate a plurality of pieces of data output from the packet processing unit to generate a data block, a data memory configured to store data output from the packet processing unit, and a combination data transfer unit configured to DMA-transfer the data block generated by the data combining unit to the data memory or write the data block to the data memory through a processor, wherein the combination data transfer unit is configured to determine an address in the data memory of a beginning of an individual piece of data in the data block, write information on the address to a descriptor that is a data area on a predetermined memory, and DMA-transfer the data block to the data memory or write the data block to the data memory through a processor.
In a first exemplary configuration of the packet processing apparatus of embodiments of the present invention, the combination data transfer unit is configured to write information on a received data size indicating a data length of the individual piece of data in the data block to the descriptor.
The first exemplary configuration of the packet processing apparatus of embodiments of the present invention further includes a processing unit configured to read data stored in the data memory, wherein the processing unit is configured to read data from the data memory based on information written to the descriptor and perform processing on the read data.
A packet processing method of embodiments of the present invention includes a first step of performing processing on a packet received from a communication line and outputting data that is a result of the processing, a second step of concatenating a plurality of pieces of data obtained in the first step to generate a data block, a third step of DMA-transferring the data block to a data memory, from which data reading is performed by a processing unit that performs processing on data obtained in the first step, or writing the data block to the data memory through a processor, and a fourth step of writing information on an address in the data memory of a beginning of an individual piece of data in the data block to a descriptor that is a data area on a predetermined memory.
A packet processing method of embodiments of the present invention includes a first step of performing processing on a packet received from a communication line and outputting data that is a result of the processing, a second step of concatenating a plurality of pieces of data obtained in the first step to generate a data block, a third step of determining an address of a beginning of an individual piece of data in the data block in a data memory from which data reading is performed by a processing unit that performs processing on data obtained in the first step, a fourth step of writing information on the address to a descriptor that is a data area on a predetermined memory, and a fifth step of DMA-transferring the data block to the data memory or writing the data block to the data memory through a processor.
According to embodiments of the present invention, the combination data transfer unit DMA-transfers the data block generated by the data combining unit to the data memory or writes the data block to the data memory through a processor and writes information on an address in the data memory of a beginning of each piece of data in the data block to a descriptor that is a data area on a predetermined memory. Compared to the configurations of the related scheme, the packet processing apparatus provided with the combination data transfer unit of embodiments of the present invention can reduce the scale of hardware required for the processing of restoring a plurality of original pieces of data from a data block into which the plurality of pieces of data have been combined and can also achieve high reception performance due to the effects of collective DMA transfer or collective writing.
Further, in embodiments of the present invention, the combination data transfer unit determines an address in the data memory of the beginning of each piece of data in the data block and writes information on the address to the descriptor, such that it is possible to reduce the size of a buffer area for data blocks that needs to be secured in the data memory as compared to the configurations of the related scheme.
When the processing of restoring a plurality of original pieces of data from a data block which the plurality of pieces of data have been combined is implemented by hardware in the configuration of embodiments of the present invention, there is an advantage that the reception performance is improved (the number of pieces of data that can be processed per unit time increases) because the processing of the processor required to process one piece of data becomes lighter as compared to when the processing of restoring a plurality of original pieces of data from a data block into which the plurality of pieces of data have been combined is implemented by software in the configuration of the related scheme of
Hereinafter, reference examples on which embodiments of the present invention are based will be described. In all drawings for explaining the reference examples and embodiments, those having the same function are denoted by the same reference signs and repeated description thereof will be omitted.
Similar to the configuration of
Of these components, the line handling unit 100, the reception buffer 105 for packet combining, and the combining threshold control unit 107 are equivalent to those in the configuration of
The packet combining unit 110 transfers a packet received by the line handling unit 100 to the reception buffer 105 for packet combining. At this time, the packet combining unit 110 stores a packet received by the line handling unit 100 in the reception buffer 105 such that the received packet and packets already stored in the reception buffer 105 are concatenated into one combination packet. Then, when the size of the combination packet in the reception buffer 105 has exceeded the threshold set in the combining threshold control unit 107, the packet combining unit 110 issues a request to transfer the combination packet to the packet memory 101.
Here, the packet combining unit 110 may also issue a transfer request when a timeout has occurred (such as when the reception interval between packets has exceeded a predetermined period) before the size of the combination packet in the reception buffer 105 has exceeded the threshold.
The packet combining unit 110 records the number of packets combined in the reception buffer 105 and the size of each packet and notifies the combination packet transfer unit 111 of the number of packets combined and the size of each packet when issuing a request to transfer the combination packet.
The combination packet transfer unit 111 includes a DMA controller 1111. The combination packet transfer unit 111 transfers the combination packet to the packet memory 101 through one DMA transfer, generates a hardware interrupt, and issues a request to activate the reception processing unit 103.
Here, the combination packet transfer unit 111 may not generate a hardware interrupt to the processor (not illustrated) of the packet processing apparatus.
The combination packet transfer unit 111 writes the size of each packet and the like to the descriptor 1110 which has been prepared for each packet by the transfer management unit 112 (software executed by the processor) using information on the number of packets combined and the size of each packet of which the packet combining unit 110 has notified. Details of the configuration of the descriptor 1110 and the operation of the combination packet transfer unit 111 will be described later.
Upon detecting an activation request, the reception processing unit 103 reads a packet from the packet memory 101 based on address information and size information written to the descriptor 1110 prepared for each packet and passes the packet to the protocol processing unit 104. The operation of the reception processing unit 103 is equivalent to that of the configuration of
The protocol processing unit 104 performs necessary protocol processing on the packet received from the reception processing unit 103. Then, when the necessary protocol processing has been completed, the protocol processing unit 104 releases an area of the packet memory 101 in which the packet passed from the reception processing unit 103 is stored. The operation of the protocol processing unit 104 is equivalent to that of the configuration of
When the necessary protocol processing has been completed and the area of the packet memory 101 in which the packet passed from the reception processing unit 103 is stored has been released, it is determined that processing in S503 of
The reception processing unit 103, the protocol processing unit 104, and the transfer management unit 112 can be realized by software that runs on a general-purpose personal computer or a workstation or can be realized by hardware such as a field programmable gate array (FPGA) that runs in cooperation with a program.
The packet memory 101 can be configured as a memory on a personal computer, a communication device, or a communication board.
The line handling unit 100, the combining threshold control unit 107, and the packet combining unit no can be made of an FPGA or the like on a communication device or a communication board.
The reception buffer 105 can be made of a storage area included in an FPGA or the like on a communication device or a communication board or a storage circuit such as a first-in first-out (FIFO).
The descriptor 1110 of
The descriptor 1110 is actually arranged in a memory on a personal computer, a communication device, or a communication board, similar to the packet memory 101.
The descriptor 1110 can be arranged in the same memory as the packet memory 101, in which case the purpose can be distinguished by the address in the memory.
Here, an exemplary operation of DMA transfer of the related scheme using the descriptor 1020 of the related scheme will be described in detail again with reference to
First, the processor of the packet processing apparatus determines and writes start addresses A #1 to A #N of the write destinations of packets to the descriptor 1020 and further rewrites valid flags AF #1 to AF #N indicating whether or not the start addresses A #1 to A #N are valid from “invalid” to “valid.”
The descriptor 1020 has N sets of areas for writing information such as the start addresses, while the order of writing to the areas is predetermined. For example, in the example of
When it becomes possible to transfer the first packet again after all start addresses are written, starts addresses are written to the descriptor 1020 in order from the first start address A #1. Whether or not a start address A #n (where n is 1 to N) can be written may be determined, for example, such that it is determined that the start address A #n can be written if a valid flag AF #n corresponding to the start address A #n is “invalid.”
Next, the DMA controller 1021 checks a valid flag AF #n in the descriptor 1020, and when the valid flag AF #n indicates that a start address A #n is “valid” (yes in
After completing this DMA transfer, the DMA controller 1021 writes a received data size L #n indicating the packet length of the nth packet to the descriptor 1020 and rewrites a reception completion flag WF #n set in the descriptor 1020 indicating that writing of the nth packet has been completed from “not completed” to “completed” (step S105 in
As described above, the descriptor 1020 has (a set of) N areas of valid flags AF #1 to AF #N, while the order in which the valid flags AF #1 to AF #N are checked is predetermined. For example, in the examples of
The descriptor 1020 also has N sets of prepared areas for writing the received data sizes L #1 to L #N and the reception completion flags WF #1 to WF #N. The DMA controller 1021 writes a reception data size L #n and a reception completion flag WF #n to areas of a number corresponding to an nth valid flag AF #n which has been confirmed as indicating that an nth start address A #n is “valid.”
Next, the processor of the packet processing apparatus periodically checks the reception completion flags WF #n in the descriptor 1020, and when a reception completion flag WF #n indicates “completed,” reads an nth packet from the packet memory 101 using information on a corresponding nth start address A #n and a corresponding nth received data size L #n and performs necessary processing (for example, protocol processing) on the read nth packet.
Then, the processor rewrites an nth valid flag AF #n in the descriptor 1020 corresponding to the nth packet for which the processing has been completed from “valid” to “invalid” and rewrites the nth reception completion flag WF #n in the descriptor 1020 from “completed” to “not completed.”
The descriptor 1020 has (a set of) N areas of reception completion flags WF #1 to WF #N, while the order in which the reception completion flags WF #1 to WF #N are checked is predetermined. For example, in the examples of
In the above operation, the DMA controller 1021 may issue an interrupt processing request to the processor after completing a DMA transfer and check reception completion flags WF #1 to WF #N upon receiving the interrupt processing request from the DMA controller 1021 instead of the processor periodically checking the reception completion flags WF #1 to WF #N.
Next, an exemplary operation of the present embodiment using the descriptor 1110 having the configuration of
First, the transfer management unit 112 (software executed by the processor) determines addresses of beginning data of N packets in the packet memory 101, that is, start addresses A #n (where n is 1 to N) of write destinations of the packets, and writes the determined addresses to the descriptor 1020 as an initial setting of the packet processing apparatus (step S300 in
The descriptor 1110 has N sets of prepared areas for writing information such as the start addresses, while the order of writing to the areas is predetermined. For example, in the example of
When it becomes possible to transfer the first packet again after all start addresses are written, starts addresses are written to the descriptor 1110 in order from the first start address A #1. Whether or not a start address A #n can be written may be determined, for example, such that it is determined that the start address A #n can be written if a valid flag AF #n corresponding to the start address A #n is “invalid.” This operation is equivalent to that of the related scheme.
First, the DMA controller 1111 in the combination packet transfer unit 111 initializes a variable n indicating the order of reading and writing from and to the descriptor 1110 to 1 (step S400 in
Then, when the packet combining unit 110 has issued a transfer request, the DMA controller 1111 checks an nth valid flag AF #n in the descriptor 1110 (step S401 in
When the valid flag AF #n indicates that the nth start address A #n is “valid” (yes in step S402 of
When the data to be transferred to the packet memory 101 is not a combination packet (when the number of packets combined is 1), the DMA controller 1111 reads the nth start address A #n confirmed as “valid” by the corresponding valid flag AF #n from the descriptor 1110 (step S404 in
After completing this DMA transfer, the DMA controller 1111 writes a received data size L #n indicating the packet length of the nth packet to the descriptor 1110 and rewrites a reception completion flag WF #n set in the descriptor 1110 indicating that writing of the nth packet has been completed from “not completed” to “completed” (step S406 in
The DMA controller 1111 determines whether or not the variable n is equal to N (step S407 in
As described above, the descriptor 1110 has (a set of) N prepared areas of valid flags AF #1 to AF #N, while the order in which the valid flags AF #1 to AF #N are checked is predetermined. For example, in the examples of
The descriptor 1110 also has N sets of prepared areas for writing the received data sizes L #1 to L #N and the reception completion flags WF #1 to WF #N. The DMA controller 1111 writes a reception data size L #n and a reception completion flag WF #n to areas of a number corresponding to an nth valid flag AF #n which has been confirmed as indicating that an nth start address A #n is “valid.”
On the other hand, when the data to be transferred to the packet memory 101 is a combination packet (when the number k of packets combined is 2 or more), the DMA controller 1111 checks the number k of packets combined (step S409 in
When n=N, the DMA controller 1111 checks the valid flags AF #1 to AF #(k−1). When n<N and n+k−1>N, the DMA controller 1111 checks the valid flags AF #(n+1) to AF #N and AF #1 to AF #(k−1−(N−n)).
When all k valid flags checked in the processing of steps S402 and S410 are “valid” (yes in step S410), the DMA controller 1111 reads an nth start address A #n corresponding to the first valid flag AF #n among the k checked valid flags from the descriptor 1110 (step S411 in
After completing this DMA transfer, the DMA controller 1111 writes to the descriptor 1110 received data sizes L #n to L #(n+k−1) indicating the packet lengths of packets constituting the combination packet DMA-transferred to the packet memory 101 based on information of which the packet combining unit 110 has notified (the size of each packet combined) (step S413 in
When n=N, the DMA controller 1111 writes the received data sizes L #n and L #1 to L #(k−1) to the descriptor 1110. When n<N and n+k−1>N, the DMA controller 1111 writes the received data sizes L #n, L #(n+1) to L #N, and L #1 to L #(k−1−(N−n)) to the descriptor 1110.
Subsequently, the DMA controller 1111 rewrites “k−1” start addresses A #(n+1) to A #(n+k−1) in the descriptor 1110 according to the packet lengths of the first “k−1” packets among the k packets constituting the combination packet (step S414 in
Specifically, the DMA controller 1111 rewrites the start address A #(n+1) to a value obtained by adding the start address A #n and the packet length of the first packet among the k packets constituting the combination packet (a value indicated by the received data size L #n). Further, the DMA controller 1111 rewrites the start address A #(n+k−1) to a value obtained by adding the start address A #(n+k−2) and the packet length of the “k−1”th packet among the k packets constituting the combination packet (a value indicated by the received data size L #(n+k−2)).
In this way, the DMA controller 1111 rewrites a start address A #i to a value obtained by adding an immediately previous start address A #(i−1) and the packet length of an “i−1”th packet among the packets constituting the combination packet.
Next, the DMA controller 1111 rewrites reception completion flags WF #n to WF #(n+k−1) corresponding to the packets constituting the combination packet DMA-transferred to the packet memory 101 from “not completed” to “completed” (step S415 in
When n=N, the DMA controller 1111 rewrites the reception completion flags WF #n and WF #1 to WF #(k−1) from “not completed” to “completed.” When n<N and n+k−1>N, the DMA controller 1111 rewrites the reception completion flags WF #n, WF #(n+1) to WF #N, and WF #1 to WF #(k−1−(N−n)) to “completed.”
Then, the DMA controller 1111 checks whether or not n+k>N is satisfied (step S416 in
In the DMA transfer of the present embodiment, a combination packet into which k packets have been concatenated is collectively transferred to the packet memory 101 and information on start addresses in the descriptor 1110 is partially rewritten in the above manner, thereby notifying the processor of the packet processing apparatus (the reception processing unit 103 and the protocol processing unit 104) of addresses where the beginnings of the packets have been written.
The reception processing unit 103 (software executed by the processor) periodically checks the reception completion flags WF #n (where n is 1 to N) of the descriptor 1110, and when a reception completion flag WF #n indicates “completed” (yes in step S501 in
After necessary processing has been performed by the protocol processing unit 104 (yes in step S503 in
The descriptor 1110 has (a set of) N areas of reception completion flags WF #1 to WF #N, while the order in which the reception completion flags WF #1 to WF #N are checked is predetermined. For example, the reception processing unit 103 (software executed by the processor) checks the reception completion flags in the order of the first reception completion flag WF #1, the second reception completion flag WF #2, . . . , and the Nth reception completion flag WF #N. After checking all reception completion flags, the reception processing unit 103 checks again the reception completion flags in order from the first reception completion flag WF #1.
Instead of periodically checking the reception completion flags WF #n in the descriptor 1110, the DMA controller 1111 may issue an interrupt processing request to the processor after completion of a DMA transfer and the reception processing unit 103 (software executed by the processor) may check the reception completion flags WF #n (where n is 1 to N) of the descriptor 1110 in response to the interrupt processing request.
The above operation of the processor (software) is equivalent to the operation of the processor (software) of the related scheme having the configuration of
As described above, the packet processing apparatus of the present reference example includes the combination packet transfer unit 11 having built-in means (the DMA controller 1111) which can realize collective DMA transfer and writes information for restoring a plurality of original packets from a combination packet to the descriptor 1110. Because the DMA controller 1111 can be implemented by hardware, it is not necessary to execute the restoration processing by software and it is possible to achieve high reception performance due to the effects of collective DMA transfer.
Compared to when the processor (software) executes the processing of restoring a plurality of original packets from a combination packet in the packet processing apparatus of the related scheme having the configuration of
Further, in the present reference example, the software for the reception processing unit 103 and the protocol processing unit 104 in the configuration of
Meanwhile, in the present reference example, an addressed area in the packet memory 101 prepared by the processor (software) is shared by a plurality of packets, such that the addressed area cannot be reused until the reception processing (transfer to the protocol processing unit 104) of all shared packets is completed.
The transfer management unit 112 (software executed by the processor) needs to prepare and set in the descriptor 1110 an addressed area having a size that allows writing of a maximum size of combination packet. The maximum size of a combination packet is a value obtained by adding a maximum allowable packet length to the threshold set in the combining threshold control unit 107.
In order to properly perform the collective DMA transfer in the packet processing apparatus of the present reference example, the transfer management unit 112 (software executed by the processor) needs to secure a buffer area of size N×DB_mux (where DB_mux is the maximum size of a combination packet) in the packet memory 101 in advance. This area securing is equivalent to that in the case of the configuration of
In the present reference example, for example, when the buffer area is prepared as a continuous area in the packet memory 101, the start address of the buffer area is the start address A #1 in
Even when the transfer destination address of a DMA transfer of a combination packet is A #N, such area securing allows the combination packet to be reliably written to a continuous area of size DB_mux ranging from that address A #N to the final address of the buffer area because the continuous area of size DB_mux has been secured in the packet memory 101.
If the area ranging from the address A #N to the final address of the buffer area is smaller than DB_mux, a part of the combination packet to be written may sometimes be written to an area where its writing is forbidden.
When the buffer area secured in the packet memory 101 is not prepared as a continuous area, but for example, as N discrete areas, N areas of size DB_mux are prepared in advance and the transfer management unit 112 (software executed by the processor) sets start addresses of the areas as A #1 to A #N, such that a combination packet can be reliably written to a continuous area of size DB_mux, avoiding the problem that the combination packet is written to an area where its writing is forbidden.
In the packet processing apparatus of the present reference example, the DMA controller 1111 rewrites information of the descriptor 1110 (such as start addresses, received data sizes, and reception completion flags) after a DMA transfer, thus eliminating the need for the restoration processing by software.
When the restoration processing is realized by hardware of the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
Further, when the restoration processing is realized by hardware of the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
On the other hand, in the packet processing apparatus of the present reference example, it is not necessary to hold information on a plurality of combination packets because the restoration processing for a combination packet has already been completed when a DMA transfer of the combination packet has been completed. Thus, the scale of hardware in the present reference example is smaller than that when the restoration processing is realized by hardware of the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
Writing information required for the restoration processing to a portion of a combination packet may also be applied as the means for the packet combining unit 106 to notify the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
However, if information required for the restoration processing is written to a portion of a combination packet, a part of the bandwidth of a bus used for the DMA transfer is occupied by the information required for the restoration processing, such that the effective bandwidth originally available for transfer of packet data is reduced, and as a result, a problem arises that the performance of the DMA transfer deteriorates.
In the packet processing apparatus of the present reference example, such effective bandwidth deterioration does not occur because it is not necessary to write information required for the restoration processing to a combination packet.
In the present reference example, an example in which the combination packet transfer unit 111 is realized by hardware has been illustrated. However, at least a part of the processing of the combination packet transfer unit 111 may be implemented by software and a processor other than the processor used for the reception processing. When at least a part of the processing of the combination packet transfer unit 111 is realized by software in this way, it is also not necessary for the reception processing unit 103 or the protocol processing unit 104 to perform the processing of restoring a plurality of original packets from a combination packet, such that it is possible to achieve high reception performance due to the effects of collective DMA transfer.
When at least a part of the processing of the combination packet transfer unit 111 is realized by software, it is also possible to achieve the advantage of reducing the scale of hardware required for the processing of restoring a plurality of original packets from a combination packet (which is an advantage due to not having to hold information on a plurality of combination packets) and the advantage of not deteriorating the effective bandwidth available for packet data transfer (which is an advantage due to not adding information required for the restoration processing to a portion of a combination packet), similar to when the combination packet transfer unit 111 is realized by hardware.
As a modification of the present reference example, areas for rewrite execution flags indicating whether or not start addresses have been rewritten may be added to the descriptor 1110. For example, when the processor that implements the transfer management unit 112 that performs initial setting of the start addresses A #1 to A #N has a cache memory, the start addresses A #1 to A #N written to the descriptor 1110 are copied into the cache memory.
However, when a start address in the descriptor 1110 is rewritten by the DMA controller 1111, corresponding information in the cache memory of the processor that implements the transfer management unit 112 may not be rewritten. Even in such a case, the processor can refer to a rewrite execution flag because the processor reads information in the descriptor 1110 rather than information in the cache memory.
Specifically, the processor reads and uses information in the cache memory upon determining that the start address in the descriptor 1110 has not been rewritten as a result of referring to the rewrite execution flag and temporarily disables the cache and directly reads and uses the start address in the descriptor 1110 upon determining that the start address in the descriptor 1110 has been rewritten.
When start addresses in the descriptor 1110 have been rewritten through the processing of step S414 of
As another modification of the present reference example, the DMA controller 1111 may prepare areas for writing changed start addresses in the descriptor 1110 separately from the areas for start addresses written by the transfer management unit 112 (software executed by the processor). In this case, the reception processing unit 103 (software executed by the processor) refers to the areas where the changed start addresses are written. Also, the processing described with reference to step S414 of
Further, the present reference example may have a configuration in which a plurality of DMA controllers 1111 and a plurality of descriptors 1110 corresponding to the DMA controllers 1111 are provided. The present reference example may also have a configuration in which the packet combining unit 110 determines the types of packets and groups packets of the same type into a combination packet or a configuration in which a plurality of DMA controllers 1111 and a plurality of descriptors 1110 are selectively used according to the packet type.
With a configuration in which a DMA controller 1111 and a descriptor 1110 are prepared for each packet type and a plurality of DMA controllers 1111 and a plurality of descriptors 1110 are selectively used according to the packet type, it becomes easier to perform different reception processing for each packet type.
The present reference example may also have a configuration in which a plurality of DMA controllers 1111 and a plurality of descriptors 1110 are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of DMA controllers 1111 and a plurality of descriptors 1110 are selectively used for each virtual machine.
With the configuration in which a plurality of DMA controllers 1111 and a plurality of descriptors 1110 are selectively used for each CPU core or each virtual machine, it is possible to improve the performance of reception processing by software as compared to when there is only one DMA controller or the like.
Next, a second reference example of the present invention will be described. The first reference example has been described with reference to the case where DMA transfer is used. However, a packet processing apparatus that does not use DMA transfer can also increase the effective throughput of writing to the packet memory using the collective writing such that a combination packet into which a plurality of packets have been concatenated is collectively written to the packet memory in some cases (such as when the packet memory is made of a dynamic random access memory (DRAM)).
The configuration of
The line handling unit 100, the packet memory 101, the reception processing unit 103, the protocol processing unit 104, the reception buffer 105, the combining threshold control unit 107, and the transfer management unit 112 are equivalent to those in the configuration of
The packet combining unit 110 of
Here, the packet combining unit 110 may also issue a transfer request when a timeout has occurred (such as when the interval between packets has exceeded a predetermined period) before the size of the combination packet in the reception buffer 105 has exceeded the threshold.
The packet combining unit 110 records the number of packets combined in the reception buffer 105 and the size of each packet and notifies the combination packet transfer unit 113 of information on the number of packets combined and the size of each packet when issuing a request to transfer the combination packet.
The combination packet transfer unit 113 (software executed by the processor) writes a combination packet into which a plurality of packets have been combined to the packet memory 101 and issues a request to activate the reception processing unit 103. The combination packet transfer unit 113 (software executed by the processor) writes information such as the size of each packet to the descriptor 1130 which has been prepared for each packet by the transfer management unit 112 (software executed by the processor) using information on the number of packets combined and the size of each packet of which the packet combining unit 110 has notified.
As illustrated in
When the valid flag AF #n indicates that a start address A #n is “valid” (yes in step S602 of
When the data to be transferred to the packet memory 101 is not a combination packet, the combination packet transfer unit 113 reads the start address A #n confirmed as “valid” by the valid flag AF #n from the descriptor 1130 (step S604 in
After completing this writing, the combination packet transfer unit 113 writes a received data size L #n to the descriptor 1130 and rewrites a reception completion flag WF #n set in the descriptor 1130 from “not completed” to “completed” (step S606 in
On the other hand, when the data to be transferred to the packet memory 101 is a combination packet, the combination packet transfer unit 113 checks the number k of packets combined (step S609 in
When all checked k valid flags are “valid” (yes in step S610), the combination packet transfer unit 113 reads a start address A #n corresponding to the first valid flag AF #n among the k checked valid flags from the descriptor 1130 (step S611 in
After completing this writing, the combination packet transfer unit 113 writes to the descriptor 1130 received data sizes L #n to L #(n+k−1) indicating the packet lengths of packets constituting the combination packet written to the packet memory 101 (step S613 in
Subsequently, the combination packet transfer unit 113 rewrites “k−1” start addresses A #(n+1) to A #(n+k−1) in the descriptor 1130 according to the packet lengths of the first “k−1” packets among the k packets constituting the combination packet (step S614 in
Next, the combination packet transfer unit 113 rewrites reception completion flags WF #n to WF #(n+k−1) corresponding to the packets constituting the combination packet written to the packet memory 101 from “not completed” to “completed” (step S615 in
The above processing of steps S609 to S615 and steps S616 to S618 is equivalent to the processing of steps S409 to S418 of
Thus, the packet processing apparatus of the present reference example includes means (the combination packet transfer unit 113) which can realize collective writing and writes information for restoring a plurality of original packets from a combination packet to the descriptor 1130. According to the present reference example, it is possible to eliminate the need to execute the restoration processing in the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 in
Further, in the present reference example, the software for the reception processing unit 103 and the protocol processing unit 104 in the configuration of
In order to properly perform the collective writing described with reference to
In the packet processing apparatus of the present reference example, the combination packet transfer unit 113 rewrites information of the descriptor 1130 (such as start addresses, received data sizes, and reception completion flags) after collective writing is completed, thus eliminating the need for the restoration processing.
When the restoration processing is realized by the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
Further, when the restoration processing is realized by the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
On the other hand, in the packet processing apparatus of the present reference example, it is not necessary to hold information on a plurality of combination packets because the restoration processing for a combination packet has already been completed when collective writing of the combination packet has been completed. Thus, the scale of hardware in the present reference example is smaller than that when the restoration processing is realized by the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
For example, when all components other than the packet memory 101 and the line handling unit 100 are realized by software in the configuration of
On the other hand, when all components other than the packet memory 101 and the line handling unit 100 are realized by software in the configuration of the present reference example, it is not necessary to hold information on a plurality of combination packets (the number of packets combined and the size of each packet). That is, it is only necessary to hold information (the number of packets combined and the size of each packet) required for the restoration processing for only one combination packet in the packet memory 101 or the like.
Namely as compared to the configuration of
Writing information required for the restoration processing to a portion of a combination packet may also be applied as the means for the packet combining unit 106 to notify the reception processing unit 103, the protocol processing unit 104, or the combination packet separation unit 108 of
In the packet processing apparatus of the present reference example, information required for the restoration processing can be held in a memory other than the packet memory 101 which does not use the bus to which the packet memory 101 is connected (a memory which permits only writing by the packet combining unit 110 and reading by the combination packet transfer unit 113), such that the deterioration of the effective bandwidth described above does not occur.
As a modification of the present reference example, areas for rewrite execution flags indicating whether or not start addresses have been rewritten may be added to the descriptor 1130, similar to the first reference example. In this case, upon rewriting start addresses in the descriptor 1130 through the processing of step S614 of
The combination packet transfer unit 113 may also prepare areas for writing changed start addresses in the descriptor 1130 separately from the areas for start addresses written by the transfer management unit 112 (software executed by the processor), similar to the first reference example.
The present reference example may also have a configuration in which the packet combining unit 110 determines the types of packets and groups packets of the same type into a combination packet or a configuration in which a plurality of descriptors 1130 are selectively used according to the packet type. With a configuration in which a descriptor 1130 is prepared for each packet type and a plurality of descriptors 1130 are selectively used according to the packet type, it becomes easier to perform different reception processing for each packet type.
The present reference example may also have a configuration in which a plurality of descriptors 1130 are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of descriptors 1130 are selectively used for each virtual machine. The configuration in which a plurality of descriptors 1130 are selectively used for each CPU core or each virtual machine improves the performance of write and read processing by software as compared to when there is only one descriptor 1130 or the like.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The first and second reference examples have been described assuming the case where received packets are transferred to the packet memory. However, in a packet processing apparatus according to embodiments of the present invention, when data which is a result of certain processing performed on a received packet is transferred to a memory, instead of when received packets are transferred to the packet memory, a plurality of pieces of data which are results of the processing are concatenated and collectively DMA-transferred or collectively written to the memory.
The configuration of
The line handling unit 100 is equivalent to that in the configuration of
The packet processing unit 114 performs processing on a packet output by the line handling unit 100 and outputs data which is a result of the processing. Content of processing that can be considered here includes various processing such as, for example, processing of extracting and outputting data of a predetermined size measured from the beginning of a packet when the length of the packet has exceeded a predetermined size, processing of extracting and outputting specific data such as an Internet Protocol (IP) header, and processing of counting up the number of packets for each packet type and outputting updated counter information.
The data combining unit 120 transfers data output by the packet processing unit 114 to the reception buffer 118 for data combining. At this time, the data combining unit 120 stores a piece of data output by the packet processing unit 114 in the reception buffer 118 such that the piece of output data and pieces of data already stored in the reception buffer 118 are concatenated into one data block. Then, when the size of the data block in the reception buffer 118 has exceeded the threshold set in the combining threshold control unit 119, the data combining unit 120 issues a request to transfer the data block to the data memory 115.
Here, the data combining unit 120 may also issue a transfer request when a timeout has occurred (such as when the reception interval between packets has exceeded a predetermined period) before the size of the data block in the reception buffer 118 has exceeded the threshold.
The data combining unit 120 records the number of pieces of data combined in the reception buffer 118 and the size of each piece of data and notifies the combination data transfer unit 121 of the number of pieces of data combined and the size of each piece of data when issuing a request to transfer the data block.
Here, notification of the size of data can be omitted if the size of each piece of data output by the packet processing unit 114 is a predetermined constant value (does not change for each packet). However, in that case, it is still necessary to notify of the number of pieces of data combined, for example, when a transfer has occurred due to a timeout.
The combination data transfer unit 121 includes a DMA controller 1211. The combination data transfer unit 121 transfers a data block into which a plurality of pieces of data have been combined to the data memory 115 through one DMA transfer, generates a hardware interrupt, and issues a request to activate the reception processing unit 117.
Here, the combination data transfer unit 121 may not generate a hardware interrupt to the processor (not illustrated) of the packet processing apparatus.
The combination data transfer unit 121 writes the size of each piece of data and the like to the descriptor 1210 which has been prepared for each piece of data by the transfer management unit 122 (software executed by the processor) using information on the number of pieces of data combined and the size of each piece of data of which the data combining unit 120 has notified. The configuration of the descriptor 1210 corresponds to that of the descriptor 1110 in
Upon detecting an activation request, the reception processing unit 117 reads data from the data memory 115 based on address information and size information written to the descriptor 1210 prepared for each piece of data and passes the data to the data processing unit 116. At the same time, the reception processing unit 117 secures a new area for the data memory 115 in the memory of the packet processing apparatus in order to replenish the portion of the data memory passed to the data processing unit 116. The operation of the reception processing unit 117 is equivalent to that of the configuration of
The data processing unit 116 performs necessary processing on the data received from the reception processing unit 117. Then, when the necessary processing has been completed, the data processing unit 116 releases an area of the data memory 115 in which the data passed from the reception processing unit 117 is stored.
The reception processing unit 117, the data processing unit 116, and the transfer management unit 122 can be realized by software that runs on a general-purpose personal computer or a workstation or can be realized by hardware such as an FPGA that runs in cooperation with a program.
The data memory 115 can be configured as a memory on a personal computer, a communication device, or a communication board.
The line handling unit 100, the packet processing unit 114, the combining threshold control unit 119, the data combining unit 120, and the combination data transfer unit 121 can be made of an FPGA or the like on a communication device or a communication board.
The reception buffer 118 can be made of a storage area included in an FPGA or the like on a communication device or a communication board or a storage circuit such as a FIFO.
Next, an exemplary operation of the present embodiment using the descriptor 1210 will be described with reference to
First, the transfer management unit 122 (software executed by the processor) determines addresses of beginnings of N pieces of data in the data memory 115, that is, start addresses A #n (where n is 1 to N) of write destinations of the pieces of data, and writes the determined addresses to the descriptor 1210 as an initial setting of the packet processing apparatus (step S300a in
First, the DMA controller 1211 in the combination data transfer unit 121 initializes a variable n indicating the order of reading and writing from and to the descriptor 1210 to 1 (step S400a in
Then, when the data combining unit 120 has issued a transfer request, the DMA controller 1211 checks an nth valid flag AF #n in the descriptor 1210 (step S401a in
When the valid flag AF #n indicates that an nth start address A #n is “valid” (yes in step S402a of
When the data to be transferred to the data memory 115 is not a data block (when the number of pieces of data combined is 1), the DMA controller 1211 reads the nth start address A #n confirmed as “valid” by the corresponding valid flag AF #n from the descriptor 1210 (step S404a in
After completing this DMA transfer, the DMA controller 1211 writes a received data size L #n indicating the data length of the nth piece of data to the descriptor 1210 and rewrites a reception completion flag WF #n set in the descriptor 1210 indicating that writing of the nth piece of data has been completed from “not completed” to “completed” (step S406a in
The DMA controller 1211 determines whether or not the variable n is equal to N (step S407a in
Similar to the first reference example, the order in which the valid flags AF #1 to AF #N are checked is predetermined. For example, in the examples of
On the other hand, when the data to be transferred to the data memory 115 is a data block (when the number k of pieces of data combined is 2 or more), the DMA controller 1211 checks the number k of pieces of data combined (step S409a in
Similar to the first reference example, when n=N, the DMA controller 1211 checks the valid flags AF #1 to AF #(k−1). When n<N and n+k−1>N, the DMA controller 1211 checks the valid flags AF #(n+1) to AF #N and AF #1 to AF #(k−1−(N−n)).
When all k valid flags checked in the processing of steps S402a and S410a are “valid” (yes in step S410a), the DMA controller 1211 reads an nth start address A #n corresponding to the first valid flag AF #n among the k checked valid flags from the descriptor 1210 (step S411a in
After completing this DMA transfer, the DMA controller 1211 writes to the descriptor 1210 received data sizes L #n to L #(n+k−1) indicating the data lengths of pieces of data constituting the data block DMA-transferred to the data memory 115 based on information of which the data combining unit 120 has notified (the size of each piece of data combined) (step S413a in
Similar to the first reference example, when n=N, the DMA controller 1211 writes the received data sizes L #n and L #1 to L #(k−1) to the descriptor 1210. When n<N and n+k−1>N, the DMA controller 1211 writes the received data sizes L #n, L #(n+1) to L #N, and L #1 to L #(k−1−(N−n)) to the descriptor 1210.
Subsequently, the DMA controller 1211 rewrites “k−1” start addresses A #(n+1) to A #(n+k−1) in the descriptor 1210 according to the data lengths of the first “k−1” pieces of data among the k pieces of data constituting the data block (step S414a in
Specifically, the DMA controller 1211 rewrites the start address A #(n+1) to a value obtained by adding the start address A #n and the data length of the first piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #n). Further, the DMA controller 1211 rewrites the start address A #(n+k−1) to a value obtained by adding the start address A #(n+k−2) and the data length of the “k−1”th piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #(n+k−2)).
In this way, the DMA controller 1211 rewrites a start address A #i to a value obtained by adding an immediately previous start address A #(i−1) and the data length of an “i−1”th piece of data among the pieces of data constituting the data block.
Next, the DMA controller 1211 rewrites reception completion flags WF #n to WF #(n+k−1) corresponding to the pieces of data constituting the data block DMA-transferred to the data memory 115 from “not completed” to “completed” (step S415a in
Similar to the first reference example, when n=N, the DMA controller 1211 rewrites the reception completion flags WF #n and WF #1 to WF #(k−1) from “not completed” to “completed.” When n<N and n+k−1>N, the DMA controller 1211 rewrites the reception completion flags WF #n, WF #(n+1) to WF #N, and WF #1 to WF #(k−1−(N−n)) to “completed.”
Then, the DMA controller 1211 checks whether or not n+k>N is satisfied (step S416a in
In the DMA transfer of the present embodiment, a data block into which k pieces of data have been concatenated is collectively transferred to the data memory 115 and information on start addresses in the descriptor 1210 is partially rewritten in the above manner, thereby notifying the processor of the packet processing apparatus (the reception processing unit 117 and the data processing unit 116) of addresses where the beginnings of the pieces of data have been written.
The reception processing unit 117 (software executed by the processor) periodically checks the reception completion flags WF #n (where n is 1 to N) of the descriptor 1210, and when a reception completion flag WF #n indicates “completed” (yes in step S501a in
After necessary processing has been performed by the data processing unit 116 (yes in step S503a in
Similar to the first reference example, the descriptor 1210 has (a set of) N areas of reception completion flags WF #1 to WF #N, while the order in which the reception completion flags WF #1 to WF #N are checked is predetermined.
Instead of periodically checking the reception completion flags WF #n in the descriptor 1210, the DMA controller 1211 may issue an interrupt processing request to the processor after completion of a DMA transfer and the reception processing unit 117 (software executed by the processor) may check the reception completion flags WF #n (where n is 1 to N) of the descriptor 1210 in response to the interrupt processing request.
As described above, the packet processing apparatus of the present embodiment includes the combination data transfer unit 121 having built-in means (the DMA controller 1211) which can realize collective DMA transfer and writes information for restoring a plurality of original pieces of data from a data block to the descriptor 1210. Because the DMA controller 1211 can be implemented by hardware, it is not necessary to execute the restoration processing by software and it is possible to achieve high reception performance due to the effects of collective DMA transfer.
Compared to when the processor (software) executes the processing of restoring a plurality of original pieces of data from a data block into which the pieces of data have been combined in the packet processing apparatus of the related scheme having the configuration of
Further, in the present embodiment, the software for the reception processing unit 117 and the data processing unit 116 in the configuration of
When the restoration processing is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Further, when the restoration processing is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
On the other hand, in the packet processing apparatus of the present embodiment, it is not necessary to hold information on a plurality of data blocks because the restoration processing for a data block has already been completed when a DMA transfer of the data block has been completed. Thus, the scale of hardware in the present embodiment is smaller than that when the restoration processing is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Writing information required for the restoration processing to a portion of a data block may also be applied as the means for the data combining unit 120 to notify the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
However, if information required for the restoration processing is written to a portion of a data block, a part of the bandwidth of a bus used for the DMA transfer is occupied by the information required for the restoration processing, such that the effective bandwidth originally available for transfer of data is reduced, and as a result, a problem arises that the performance of the DMA transfer deteriorates.
In the packet processing apparatus of the present embodiment, such effective bandwidth deterioration does not occur because it is not necessary to write information required for the restoration processing to a data block.
In the present embodiment, an example in which the combination data transfer unit 121 is realized by hardware has been illustrated. However, at least a part of the processing of the combination data transfer unit 121 may be implemented by software and a processor other than the processor used for the reception processing. When at least a part of the processing of the combination data transfer unit 121 is realized by software in this way, it is also not necessary for the reception processing unit 117 or the data processing unit 116 to perform the processing of restoring a plurality of original pieces of data from a data block, such that it is possible to achieve high reception performance due to the effects of collective DMA transfer.
When at least a part of the processing of the combination data transfer unit 121 is realized by software, it is also possible to achieve the advantage of reducing the scale of hardware required for the processing of restoring a plurality of original pieces of data from a data block (which is an advantage due to not having to hold information on a plurality of data blocks) and the advantage of not deteriorating the effective bandwidth available for data transfer (which is an advantage due to not adding information required for the restoration processing to a portion of a data block), similar to when the combination data transfer unit 121 is realized by hardware.
Further, the present embodiment may have a configuration in which a plurality of DMA controllers 1211 and a plurality of descriptors 1210 corresponding to the DMA controllers 1211 are provided. The present embodiment may also have a configuration in which the data combining unit 120 determines the types of pieces of data and group pieces of data of the same type into a data block or a configuration in which a plurality of DMA controllers 1211 and a plurality of descriptors 1210 are selectively used according to the data type.
With a configuration in which a DMA controller 1211 and a descriptor 1210 are prepared for each data type and a plurality of DMA controllers 1211 and a plurality of descriptors 1210 are selectively used according to the data type, it becomes easier to perform different reception processing for each data type.
The present embodiment may also have a configuration in which a plurality of DMA controllers 1211 and a plurality of descriptors 1210 are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of DMA controllers 1211 and a plurality of descriptors 1210 are selectively used for each virtual machine.
With the configuration in which a plurality of DMA controllers 1211 and a plurality of descriptors 1210 are selectively used for each CPU core or each virtual machine, it is possible to improve the performance of reception processing by software as compared to when there is only one DMA controller or the like.
Next, a second embodiment of the present invention will be described.
The configuration of
The line handling unit 100, the data memory 115, the data processing unit 116, the reception processing unit 117, the reception buffer 118, the combining threshold control unit 119, and the transfer management unit 122 are equivalent to those in the configuration of
The data combining unit 120 in
Here, the data combining unit 120 may also issue a transfer request when a timeout has occurred (such as when the interval between packets has exceeded a predetermined period) before the size of the data block in the reception buffer 118 has exceeded the threshold.
The data combining unit 120 records the number of pieces of data combined in the reception buffer 118 and the size of each piece of data and notifies the combination data transfer unit 123 of information on the number of pieces of data combined and the size of each piece of data when issuing a request to transfer the data block.
Here, notification of the size of data can be omitted if the size of each piece of data output by the packet processing unit 114 is a predetermined constant value (does not change for each packet). However, in that case, it is still necessary to notify of the number of pieces of data combined, for example, when a transfer has occurred due to a timeout.
The combination data transfer unit 123 (software executed by the processor) writes a data block into which a plurality of pieces of data have been combined to the data memory 115 and issues a request to activate the reception processing unit 117. The combination data transfer unit 123 (software executed by the processor) writes information such as the size of each piece of data to the descriptor 1230 which has been prepared for each piece of data by the transfer management unit 122 (software executed by the processor) using information on the number of pieces of data combined and the size of each piece of data of which the data combining unit 120 has notified.
The configuration of the descriptor 1230 is equivalent to that of the descriptor 1210 of the first embodiment. However, the present embodiment differs in that the combination data transfer unit 123 (software executed by the processor), instead of the combination data transfer unit 121, performs writing to the descriptor 1230.
When the valid flag AF #n indicates that a start address A #n is “valid” (yes in step S602a of
When the data to be transferred to the data memory 115 is not a data block, the combination data transfer unit 123 reads the start address A #n confirmed as “valid” by the valid flag AF #n from the descriptor 1230 (step S604a in
After completing this writing, the combination data transfer unit 123 writes a received data size L #n to the descriptor 1230 and rewrites a reception completion flag WF #n set in the descriptor 1230 from “not completed” to “completed” (step S606a in
On the other hand, when the data to be transferred to the data memory 115 is a data block, the combination data transfer unit 123 checks the number k of pieces of data combined (step S609a in
When all checked k valid flags are “valid” (yes in step S610a), the combination data transfer unit 123 reads a start address A #n corresponding to the first valid flag AF #n among the k checked valid flags from the descriptor 1230 (step S611a in
After completing this writing, the combination data transfer unit 123 writes to the descriptor 1230 received data sizes L #n to L #(n+k−1) indicating the data lengths of pieces of data constituting the data block written to the data memory 115 (step S613a in
Subsequently, the combination data transfer unit 123 rewrites “k−1” start addresses A #(n+1) to A #(n+k−1) in the descriptor 1230 according to the data lengths of the first “k−1” pieces of data among the k pieces of data constituting the data block (step S614a in
Next, the combination data transfer unit 123 rewrites reception completion flags WF #n to WF #(n+k−1) corresponding to the pieces of data constituting the data block written to the data memory 115 from “not completed” to “completed” (step S615a in
The above processing of steps S609a to S615a and steps S616a to S618a is equivalent to the processing of steps S409a to S418a of
Thus, the packet processing apparatus of the present embodiment includes means (the combination data transfer unit 123) which can realize collective writing and writes information for restoring a plurality of original pieces of data from a data block to the descriptor 1230. According to the present embodiment, it is possible to eliminate the need to execute the restoration processing in the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b in
Further, in the present embodiment, the software for the reception processing unit 117 and the data processing unit 116 in the configuration of
When the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Further, when the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
On the other hand, in the packet processing apparatus of the present embodiment, it is not necessary to hold information on a plurality of data blocks because the restoration processing for a data block has already been completed when collective writing of the data block has been completed. Thus, the scale of hardware in the present embodiment is smaller than that when the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
For example, when all components other than the data memory 115 and the line handling unit 100 are realized by software in the configuration of
On the other hand, when all components other than the data memory 115 and the line handling unit 100 are realized by software in the configuration of the present embodiment, it is not necessary to hold information on a plurality of data blocks (the number of pieces of data combined and the size of each piece of data). That is, it is only necessary to hold information (the number of pieces of data combined and the size of each piece of data) required for the restoration processing for only one data block in the data memory 115 or the like.
Namely as compared to the configuration of
Writing information required for the restoration processing to a portion of a data block may also be applied as the means for the data combining unit 120 to notify the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
In the packet processing apparatus of the present embodiment, information required for the restoration processing can be held in a memory other than the data memory 115 which does not use the bus to which the data memory 115 is connected (a memory which permits only writing by the data combining unit 120 and reading by the combination data transfer unit 123), such that the deterioration of the effective bandwidth described above does not occur.
The present embodiment may also have a configuration in which the data combining unit 120 determines the types of pieces of data and group pieces of data of the same type into a data block or a configuration in which a plurality of descriptors 1230 are selectively used according to the data type. With a configuration in which a descriptor 1230 is prepared for each data type and a plurality of descriptors 1230 are selectively used according to the data type, it becomes easier to perform different reception processing for each data type.
The present embodiment may also have a configuration in which a plurality of descriptors 1230 are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of descriptors 1230 are selectively used for each virtual machine. The configuration in which a plurality of descriptors 1230 are selectively used for each CPU core or each virtual machine improves the performance of write and read processing by software as compared to when there is only one descriptor 1230 or the like.
Next, a third embodiment of the present invention will be described.
The line handling unit 100, the packet processing unit 114, the data memory 115, the data processing unit 116, the reception processing unit 117, the reception buffer 118, the combining threshold control unit 119, and the data combining unit 120 in
The combination data transfer unit 121a in
Here, the combination data transfer unit 121a may not generate a hardware interrupt to the processor (not illustrated) of the packet processing apparatus.
The combination data transfer unit 121a writes the size of each piece of data and the like to the descriptor 1210a which has been prepared for each piece of data by the transfer management unit 122a (software executed by the processor) using information on the number of pieces of data combined and the size of each piece of data of which the data combining unit 120 has notified.
The descriptor 1210a of
The descriptor 1210a is actually arranged in a memory on a personal computer, a communication device, or a communication board, similar to the data memory 115.
The descriptor 1210a can be arranged in the same memory as the data memory 115, in which case the purpose can be distinguished by the address in the memory.
Next, an exemplary operation of the present embodiment using the descriptor 1210a having the configuration of
First, as an initial setting of the packet processing apparatus, the transfer management unit 122a (software executed by the processor) secures a continuous area in the data memory 115 as a buffer area for data blocks (step S700 in
A plurality of control registers 124 may also be prepared although there is no problem with only one (set of) control register 124. When a plurality of control registers 124 are provided, the order in which they are used to write data is predetermined. The control register 124 is set at the time of initial setting and the setting is not changed during operation.
Next, as an initial setting of the descriptor 1210a, the transfer management unit 122a sets all valid flags AF #n indicating whether start addresses A #n (where n is 1 to N) are valid or not to “invalid” (step S702 in
When the data combining unit 120 has issued a transfer request, the DMA controller 1211a in the combination data transfer unit 121a reads the start address A0 and the capacity (size) C0 set by the transfer management unit 122a from the control register 124 if the transfer request is the first after the above initial setting (step S800 in
Subsequently, the DMA controller 1211a initializes a variable n indicating the order of reading and writing from and to the descriptor 1210a to 1 (step S802 in
The DMA controller 1211a checks information from the data combining unit 120, checks whether data to be transferred to the data memory 115 is a single piece of data which has not been combined or a data block, and checks the number k of pieces of data combined (step S803 in
When n=N, the DMA controller 1211a checks reception completion flags of WF #N and WF #1 to WF #(k−1). When n<N and n+k−1>N, the DMA controller 1211a checks reception completion flags WF #n to WF #N and WF #1 to WF #(k−1−(N−n)).
When all k reception completion flags checked through the processing of step S804 are “completed” (yes in step S804), the DMA controller 1211a compares a remaining capacity CR of the buffer area for data blocks in the data memory 115 with the size CD of the data to be transferred to the data memory 115 (step S805 in
In the comparison, the DMA controller 1211a calculates the remaining capacity CR of the buffer area for data blocks in the data memory 115 based on the write pointer WP and a read pointer RP. Specifically, in an initial state (where write pointer WP=read pointer RP), the DMA controller 1211a uses the value of the capacity (size) C0 read from the control register 124 in step S800 as the remaining capacity CR as it is.
When write pointer WP>read pointer RP, the DMA controller 1211a calculates C0−WP+RP as the remaining capacity CR, and when write pointer WP<read pointer RP, calculates RP−WP as the remaining capacity CR. When write pointer WP=read pointer RP other than in the initial state, the DMA controller 1211a calculates 0 or C0 as the remaining capacity CR. Specifically, when a transition has been made from the state of write pointer WP>read pointer RP to the state of write pointer WP=read pointer RP, the DMA controller 1211a determines that the read pointer has been updated and sets the remaining capacity CR to C0, and when a transition has been made from the state of write pointer WP<read pointer RP to the state of write pointer WP=read pointer RP, the DMA controller 1211a determines that the write pointer has been updated and sets the remaining capacity CR to 0.
As described above, the descriptor 1210a has (a set of) N prepared areas of reception completion flags WF #1 to WF #N, while the order in which the reception completion flags WF #1 to WF #N are checked is predetermined. For example, in the examples of
When the remaining capacity CR of the buffer area for data blocks in the data memory 115 is smaller than the size CD of the data to be transferred to the data memory 115 (yes in step S805), the DMA controller 1211a returns to step S804. The state where the remaining capacity CR of the buffer area is smaller than the data size CD is resolved when the remaining capacity CR of the buffer area has been recovered by reading data from the data memory 115 by software.
When the remaining capacity CR of the buffer area is not less than the size CD of the data to be transferred to the data memory 115 (no in step S805), the DMA controller 1211a compares a value (WP+CD) obtained by adding the size CD of the data to be transferred to the data memory 115 to the write pointer WP with a predetermined upper limit value (step S806 in
When the value (WP+CD) obtained by adding the data size CD to the write pointer WP is smaller than the upper limit value (A0+C0) (yes in step S806), the DMA controller 1211a writes received data sizes L #n to L #(n+k−1) indicating the data lengths of k pieces of data constituting the data to be transferred to the data memory 115 to the descriptor 1210a based on the information (the size of each piece of data combined) of which the data combining unit 120 has notified (step S807 in
Subsequently, the DMA controller 1211a writes the value of the write pointer WP to the descriptor 1210a as the value of the nth start address A #n (step S808 in
On the other hand, when the data to be transferred to the data memory 115 is a data block (yes in step S809), the DMA controller 1211a writes “k−1” start addresses A #(n+1) to A #(n+k−1) to the descriptor 1210a according to the data lengths of the first “k−1” pieces of data among the k pieces of data constituting the data block (step S811 in
Specifically, as the start address A #(n+1), the DMA controller 1211a writes a value obtained by adding the start address A #n and the data length of the first piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #n). Further, as the start address A #(n+k−1), the DMA controller 1211a writes a value obtained by adding the start address A #(n+k−2) and the data length of the “k−1”th piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #(n+k−2)).
In this way, as a start address A #i, the DMA controller 1211a writes a value obtained by adding an immediately previous start address A #(i−1) and the data length of an “i−1”th piece of data among the pieces of data constituting the data block.
When n=N, the DMA controller 1211a writes the received data sizes L #n and L #1 to L #(k−1) to the descriptor 1210a and writes the start addresses A #n and A #1 to A #(k−1) to the descriptor 1210a. When n<N and n+k−1>N, the DMA controller 1211a writes the received data sizes L #n, L #(n+1) to L #N, and L #1 to L #(k−1−(N−n)) to the descriptor 1210a and writes the start addresses A #n and A #(n+1) to A #N and A #1 to A #(k−1−(N−n)) to the descriptor 1210a.
Next, the DMA controller 1211a performs a DMA transfer to write the data to be transferred to the data memory 115 (a single piece of data or a data block) to a buffer area starting from a start address of the transfer destination in the data memory 115 using the write pointer WP as the start address of the transfer destination in the data memory 115 (step S812 in
Then, the DMA controller 1211a adds the size of the data DMA-transferred to the data memory 115 (a single piece of data or a data block) to the write pointer WP (step S813 in FIG. 24). Specifically, when the data DMA-transferred to the data memory 115 by the DMA controller 1211a is a single piece of data which has not been combined (k=1), the DMA controller 1211a adds the data length of the data (a value indicated by the received data size L #n) to the write pointer WP. When the data to be transferred to the data memory 115 is a data block, the DMA controller 1211a adds the received data sizes L #n to L #(n+k−1) to the write pointer WP.
When n=N, the DMA controller 1211a adds the received data sizes L #n and L #i to L #(k−1) to the write pointer WP. When n<N and n+k−1>N, the DMA controller 1211a adds the received data sizes L #n, L #(n+1) to L #N, and L #1 to L #(k−1−(N−n)) to the write pointer WP.
Next, the DMA controller 1211a rewrites the reception completion flags WF #n to WF #(n+k−1) corresponding to the pieces of data constituting the data DMA-transferred to the data memory 115 from “completed” to “not completed” (step S814 in
When n=N, the DMA controller 1211a rewrites the reception completion flags WF #n and WF #i to WF #(k−1) from “completed” to “not completed” and rewrites the valid flags AF #n and AF #i to AF #(k−1) from “invalid” to “valid.” When n<N and n+k−1>N, the DMA controller 1211a rewrites the reception completion flags WF #n, WF #(n+1) to WF #N, and WF #i to WF #(k−1−(N−n)) to “not completed” and rewrites the valid flags AF #n, AF #(n+1) to AF #N, and AF #1 to AF #(k−1−(N−n)) to “valid.”
Then, the DMA controller 1211a checks whether n+k>N is satisfied (step S816 in
On the other hand, when the value (WP+CD) obtained by adding the size CD of the data to be transferred to the data memory 115 to the write pointer WP is not less than the upper limit value (A0+C0) (no in step S806), the DMA controller 1211a compares the size CD of the data with the value (RP−A0) obtained by subtracting the start address A0 of the buffer area in the data memory 115 from the read pointer RP (step S819 in
When the data size CD is smaller than the subtraction result (RP−A0) (yes in step S819), the DMA controller 1211a writes received data sizes L #n to L #(n+k−1) indicating the data lengths of k pieces of data constituting the data to be transferred to the data memory 115 to the descriptor 1210a based on the information (the size of each piece of data combined) of which the data combining unit 120 has notified (step S820 in
Subsequently, the DMA controller 1211a writes the value of the start address A0 of the buffer area in the data memory 115 to the descriptor 1210a as the value of the nth start address A #n (step S821 in
On the other hand, when the data to be transferred to the data memory 115 is a data block (yes in step S822), the DMA controller 1211a writes “k−1” start addresses A #(n+1) to A #(n+k−1) to the descriptor 1210a according to the data lengths of the first “k−1” pieces of data among the k pieces of data constituting the data block (step S824 in
Specifically, as the start address A #(n+1), the DMA controller 1211a writes a value obtained by adding the start address A #n and the data length of the first piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #n). Further, as the start address A #(n+k−1), the DMA controller 1211a writes a value obtained by adding the start address A #(n+k−2) and the data length of the “k−1”th piece of data among the k pieces of data constituting the data block (a value indicated by the received data size L #(n+k−2)). In this way, as a start address A #i, the DMA controller 1211a writes a value obtained by adding an immediately previous start address A #(i−1) and the data length of an “i−1”th piece of data among the pieces of data constituting the data block.
When n=N, the DMA controller 1211a writes the received data sizes L #n and L #1 to L #(k−1) to the descriptor 1210a and writes the start addresses A #n and A #1 to A #(k−1) to the descriptor 1210a. When n<N and n+k−1>N, the DMA controller 1211a writes the received data sizes L #n, L #(n+1) to L #N, and L #1 to L #(k−1−(N−n)) to the descriptor 1210a and writes the start addresses A #n and A #(n+1) to A #N and A #1 to A #(k−1−(N−n)) to the descriptor 1210a.
Next, the DMA controller 1211a performs a DMA transfer to write the data to be transferred to the data memory 115 (a single piece of data or a data block) to a buffer area starting from the start address A0 in the data memory 115 (step S825 in
Then, the DMA controller 1211a updates the write pointer WP to a new value obtained by adding the size of the data DMA-transferred to the data memory 115 (a single piece of data or a data block) to the start address A0 of the buffer area of the data memory 115 (step S826 in
When n=N, the DMA controller 1211a sets a value obtained by adding the received data sizes L #n and L #i to L #(k−1) to the start address A0 as a new value of the write pointer WP. When n<N and n+k−1>N, the DMA controller 1211a sets a value obtained by adding the received data sizes L #n, L #(n+1) to L #N, and L #i to L #(k−1−(N−n)) to the start address A0 as a new value of the write pointer WP.
Next, the DMA controller 1211a rewrites the reception completion flags WF #n to WF #(n+k−1) corresponding to the pieces of data constituting the data DMA-transferred to the data memory 115 from “completed” to “not completed” (step S827 in
When n=N, the DMA controller 1211a rewrites the reception completion flags WF #n and WF #i to WF #(k−1) from “completed” to “not completed” and rewrites the valid flags AF #n and AF #i to AF #(k−1) from “invalid” to “valid.” When n<N and n+k−1>N, the DMA controller 1211a rewrites the reception completion flags WF #n, WF #(n+1) to WF #N, and WF #i to WF #(k−1−(N−n)) to “not completed” and rewrites the valid flags AF #n, AF #(n+1) to AF #N, and AF #1 to AF #(k−1−(N−n)) to “valid.”
Then, the DMA controller 1211a checks whether n+k>N is satisfied (step S829 in
In the DMA transfer of the present embodiment, a data block into which k pieces of data have been concatenated is collectively transferred to the data memory 115 and information on start addresses in the descriptor 1210a is written by the DMA controller 1211a in the above manner, thereby notifying the processor of the packet processing apparatus (the reception processing unit 117 and the data processing unit 116) of addresses where the beginnings of the pieces of data have been written.
The DMA controller 1211a also performs processing of updating the read pointer RP in accordance with processing of the reception processing unit 117 and the like (software executed by the processor) which is described below, and details of the update processing of the read pointer RP will be described later.
The reception processing unit 117 (software executed by the processor) periodically checks the valid flags AF #n (where n is 1 to N) of the descriptor 1210a, and when a valid flag AF #n indicates “valid” (yes in step S901 in
After necessary processing has been performed by the data processing unit 116 (yes in step S903 in
Similar to the first embodiment, the descriptor 1210a has (a set of) N areas of valid flags AF #1 to AF #N, while the order in which the valid flags AF #1 to AF #N are checked is predetermined.
Instead of periodically checking the valid flags AF #n in the descriptor 1210a, the DMA controller 1211a may issue an interrupt processing request to the processor after completion of a DMA transfer and the reception processing unit 117 (software executed by the processor) may check the valid flags AF #n (where n is 1 to N) of the descriptor 1210a in response to the interrupt processing request.
Next, the update processing of the read pointer RP performed by the DMA controller 1211a will be described. First, the DMA controller 1211a sets the start address A0 of the buffer area for data blocks in the data memory 115 as an initial value of the read pointer RP (step S840 in
The DMA controller 1211a periodically checks the nth valid flags AF #n in the descriptor 1210a during the processing of
When the nth reception completion flag WF #n in the descriptor 1210a indicates “completed” (yes in step S845 of
When the valid flag AF #n has not been rewritten to “invalid” by software executed by the processor, the DMA controller 1211a updates the valid flag AF #n to “invalid” (step S847 in
The DMA controller 1211a determines whether the variable n is equal to N (step S848 in
The reception completion flag WF #n becomes “completed” by the operation of the reception processing unit 117 in
Here, the DMA controller 1211a uses the read pointer RP described above to calculate the remaining capacity of the buffer area for data blocks in the data memory 115, and use of the read pointer RP for reading by software or the like is not assumed.
As described above, the packet processing apparatus of the present embodiment includes the combination data transfer unit 121a having built-in means (the DMA controller 1211a) which can realize collective DMA transfer and writes information for restoring a plurality of original pieces of data from a data block to the descriptor 1210a. Because the DMA controller 12n1a can be implemented by hardware, it is not necessary to execute the restoration processing by software and it is possible to achieve high reception performance due to the effects of collective DMA transfer.
Compared to when the processor (software) executes the processing of restoring a plurality of original pieces of data from a data block into which the pieces of data have been combined in the packet processing apparatus of the related scheme having the configuration of
In order to properly perform collective DMA transfer in the configuration of the related scheme of
The maximum size of a data block DB_mux is a value obtained by adding the allowable maximum data length to the threshold set in the combining threshold control unit 119. Thus, for example, when the threshold is 500 bytes, the maximum allowable data length is 2000 bytes, and N is 10, the size of a buffer area that needs to be secured in the data memory 115 in the configuration of the related scheme of
The size of a buffer area that needs to be secured in the data memory 115 in the packet processing apparatus of the present embodiment is the maximum size of a data block DB_mux without depending on N. That is, the size of a buffer area that needs to be secured in the data memory 115 in the packet processing apparatus of the present embodiment is 2500 bytes under the same conditions as above. This reduction in the size of the buffer area is an advantage due to implementation of a function of, when the remaining capacity CR of the buffer area is small, suspending a DMA transfer until the remaining capacity CR reaches the required amount (step S805 in
Thus, in the present embodiment, the probability that the next DMA transfer will be suspended until reading of data from the data memory 115 by software is completed increases when the size of the buffer area secured in the data memory 115 decreases.
The following is a comparison of the size of an area wasted when the size of the buffer area secured in the data memory 115 in the packet processing apparatus of the present embodiment is the same as the size required in the configuration of the related scheme of
When the threshold is 500 bytes, the maximum allowable data length is 2000 bytes, and N is 10, the sizes of data blocks actually transferred to the data memory 115 are 501 to 2500 bytes as described above. That is, in the configuration of the related scheme of
When the size of the buffer area secured in the data memory 115 in the configuration of the present embodiment is 25000 bytes, 25000 bytes is secured as a continuous area, such that a plurality of data blocks can be written to the continuous area. Thus, in the present embodiment, only a value obtained by subtracting 1 byte from the maximum size of a data block of 2500 bytes, that is, 2499 bytes, is wasted. This value indicates that 11 or more data blocks can be written to a buffer of the same capacity (25000 bytes) when the average size S of a data block is smaller than (25000-2499)/10=2250.1 and N is 11 or more. In order to write 11 or more data blocks in the configuration of the related scheme of
Thus, when the size of the buffer area secured in the data memory 115 in the packet processing apparatus of the present embodiment is the same as the size required in the configuration of the related scheme of
When the size of a buffer area to be secured in the data memory 115 in the packet processing apparatus of the present embodiment is calculated assuming that the average size S of a data block is 1500 bytes and the maximum number of data blocks to be written to the buffer area is 10, the size of the buffer area to be secured is 1500×10=15000 bytes, which is smaller than the size (25000 bytes) required in the configuration of the related scheme of
In the configuration of the present embodiment, the maximum number of data blocks to be written to the buffer area of the data memory 115 and N of the descriptor 1210a can be independently determined. As described above, the size of the buffer area may be determined from the maximum number of data blocks to be written to the buffer area and N may be set to the maximum number of pieces of data to be written to the buffer area. However, the maximum number of pieces of data that can be actually written to the buffer area is N or less because the maximum number of pieces of data depends on the size of data to be stored and the size of the buffer area. Assuming that the average size S of a data block is 1500 bytes, the average of the number k of pieces of data combined is 2, and the maximum number of data blocks to be written to the buffer area is 10, it is desirable that the size of the buffer area be 1500×10=15000 bytes and N be 2×10=20.
When the processing of restoring a plurality of original pieces of data from a data block into which the plurality of pieces of data have been combined is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Further, when the restoration processing is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
On the other hand, in the packet processing apparatus of the present embodiment, it is not necessary to hold information on a plurality of data blocks because the restoration processing for a data block has already been completed when a DMA transfer of the data block has been completed. Thus, the scale of hardware in the present embodiment is smaller than that when the restoration processing is realized by hardware of the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Writing information required for the restoration processing to a portion of a data block may also be applied as the means for the data combining unit 120 to notify the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
In the packet processing apparatus of the present embodiment, such effective bandwidth deterioration does not occur because it is not necessary to write information required for the restoration processing to a data block.
In the present embodiment, an example in which the combination data transfer unit 121a is realized by hardware has been illustrated. However, at least a part of the processing of the combination data transfer unit 121a may be implemented by software and a processor other than the processor used for the reception processing. When at least a part of the processing of the combination data transfer unit 121a is realized by software in this way, it is also not necessary for the reception processing unit 117 or the data processing unit 116 to perform the processing of restoring a plurality of original pieces of data from a data block, such that it is possible to achieve high reception performance due to the effects of collective DMA transfer.
When at least a part of the processing of the combination data transfer unit 121a is realized by software, it is also possible to achieve the advantage of reducing the scale of hardware required for the processing of restoring a plurality of original pieces of data from a data block (which is an advantage due to not having to hold information on a plurality of data blocks) and the advantage of not deteriorating the effective bandwidth available for data transfer (which is an advantage due to not adding information required for the restoration processing to a portion of a data block), similar to when the combination data transfer unit 121a is realized by hardware.
Further, the present embodiment may have a configuration in which a plurality of DMA controllers 1211a and a plurality of descriptors 1210a corresponding to the DMA controllers 1211a are provided. The present embodiment may also have a configuration in which the data combining unit 120 determines the types of pieces of data and group pieces of data of the same type into a data block or a configuration in which a plurality of DMA controllers 1211a and a plurality of descriptors 1210a are selectively used according to the data type.
With a configuration in which a DMA controller 1211a and a descriptor 1210a are prepared for each data type and a plurality of DMA controllers 1211a and a plurality of descriptors 1210a are selectively used according to the data type, it becomes easier to perform different reception processing for each data type.
The present embodiment may also have a configuration in which a plurality of DMA controllers 1211a and a plurality of descriptors 1210a are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of DMA controllers 1211a and a plurality of descriptors 1210a are selectively used for each virtual machine.
With the configuration in which a plurality of DMA controllers 1211a and a plurality of descriptors 1210a are selectively used for each CPU core or each virtual machine, it is possible to improve the performance of reception processing by software as compared to when there is only one DMA controller or the like.
Next, a fourth embodiment of the present invention will be described.
The configuration of
The line handling unit 100, the data memory 115, the data processing unit 116, the reception processing unit 117, the reception buffer 118, the combining threshold control unit 119, the transfer management unit 122a, and the control register 124 are equivalent to those in the configuration of
The combination data transfer unit 123a (software executed by the processor) writes a data block into which a plurality of pieces of data have been combined to the data memory 115 and issues a request to activate the reception processing unit 117. The combination data transfer unit 123a writes information such as the size of each piece of data to the descriptor 1230a which has been prepared for each piece of data by the transfer management unit 122a (software executed by the processor) using information on the number of pieces of data combined and the size of each piece of data of which the data combining unit 120 has notified.
The configuration of the descriptor 1230a is equivalent to that of the descriptor 1210a of the third embodiment. However, the present embodiment differs in that the combination data transfer unit 123a (software executed by the processor), instead of the combination data transfer unit 121a, performs writing to the descriptor 1230a.
Subsequently, the combination data transfer unit 123a performs processing of steps S1002 to S1006 equivalent to the processing of steps S802 to S806. When the value (WP+CD) obtained by adding the data size CD to the write pointer WP is smaller than the upper limit value (A0+C0) (yes in step S1006 in
Processing of steps S1008 to S1011 of
Next, the combination data transfer unit 123a writes the data to be transferred to the data memory 115 (a single piece of data or a data block) to a buffer area starting from a start address of the transfer destination in the data memory 115 using the write pointer WP as the start address of the transfer destination in the data memory 115 (step S1012 in
Processing of steps S1013 to S1018 of
When the value (WP+CD) obtained by adding the size CD of the data to be transferred to the data memory 115 to the write pointer WP is not less than the upper limit value (A0+C0) (no in step S1006 in
When the data size CD is smaller than the subtraction result (RP−A0) (yes in step S1019), the combination data transfer unit 123a writes received data sizes L #n to L #(n+k−1) indicating the data lengths of k pieces of data constituting the data to be transferred to the data memory 115 to the descriptor 1210a based on the information (the size of each piece of data combined) of which the data combining unit 120 has notified (step S1020 in
Processing of steps S1021 to S1024 of
Next, the combination data transfer unit 123a writes the data to be transferred to the data memory 115 (a single piece of data or a data block) to a buffer area starting from the start address A0 in the data memory 115 (step S1025 in
Processing of steps S1026 to S1031 of
Next, the update processing of the read pointer RP performed by the combination data transfer unit 123a will be described. First, the combination data transfer unit 123a sets the start address A0 of the buffer area for data blocks in the data memory 115 as an initial value of the read pointer RP (step S1040 in
Processing of steps S1042 to S1050 in
Thus, the packet processing apparatus of the present embodiment includes means (the combination data transfer unit 123a) which can realize collective writing and writes information for restoring a plurality of original pieces of data from a data block into which the plurality of pieces of data have been combined to the descriptor 1230a. According to the present embodiment, it is possible to eliminate the need to execute the restoration processing in the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b in
In order to properly perform collective writing in the configuration of the related scheme of
On the other hand, in the packet processing apparatus of the present embodiment, collective writing can be properly performed with a smaller buffer area, similar to the configuration of
In the packet processing apparatus of the present embodiment, the combination data transfer unit 123a writes information (such as start addresses, received data sizes, and reception completion flags) to the descriptor 1230a, thus eliminating the need for the restoration processing.
When the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
Further, when the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
On the other hand, in the packet processing apparatus of the present embodiment, it is not necessary to hold information on a plurality of data blocks because the restoration processing for a data block has already been completed when collective writing of the data block has been completed. Thus, the scale of hardware in the present embodiment is smaller than that when the restoration processing is realized by the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
For example, if the processing of writing to the data memory 115 and the reception processing including the restoration processing are implemented by different processors (or virtual machines or the like) when all components other than the data memory 115 and the line handling unit 100 are realized by software in the configuration of
On the other hand, if the processing of writing to the data memory 115 and the reception processing not including the restoration processing are implemented by different processors (or virtual machines or the like) when all components other than the data memory 115 and the line handling unit 100 are realized by software in the configuration of the present embodiment, the processing of writing to the data memory 115 and the restoration processing are implemented by the same processor (or virtual machine or the like), such that it is not necessary to hold information on a plurality of data blocks (the number of pieces of data combined and the size of each piece of data), that is, it is only necessary to hold information required for the restoration processing for only one data block (the number of pieces of data combined and the size of each piece of data) in the data memory 115 or the like.
Namely as compared to the configuration of
Writing information required for the restoration processing to the data memory 115 may also be applied as the means for the data combining unit 120 to notify the reception processing unit 117, the data processing unit 116, or the combination data separation unit 108b of
In the packet processing apparatus of the present embodiment, information required for the restoration processing can be held in a memory other than the data memory 115 which does not use the bus to which the data memory 115 is connected (a memory which permits only writing by the data combining unit 120 and reading by the combination data transfer unit 123a), such that the deterioration of the effective bandwidth described above does not occur.
Similar to the third embodiment, a modification of the present embodiment may have a configuration in which the data combining unit 120 determines the types of pieces of data and group pieces of data of the same type into a data block or a configuration in which a plurality of descriptors 1230a are selectively used according to the data type. With a configuration in which a descriptor 1230a is prepared for each data type and a plurality of descriptors 1230a are selectively used according to the data type, it becomes easier to perform different reception processing for each data type.
The present embodiment may also have a configuration in which a plurality of descriptors 1230a are selectively used for each core of a processor which has a plurality of CPU cores or a configuration in which a plurality of descriptors 1230a are selectively used for each virtual machine. The configuration in which a plurality of descriptors 1230a are selectively used for each CPU core or each virtual machine improves the performance of write and read processing by software as compared to when there is only one descriptor 1230a or the like.
In the packet processing apparatus of the second embodiment and the fourth embodiment, the data memory 115, the transfer management units 122 and 122a, the data processing unit 116, the reception processing unit 117, and the combination data transfer units 123 and 123a can be realized by a computer including a processor, a storage device, and an interface and a program that controls these hardware resources. Also, part of the processing of the combination data transfer units 121 and 121a can be realized by a computer as described above.
An exemplary configuration of the computer is illustrated in
The present invention can be applied to a technology for performing protocol processing, transfer processing, or the like of communication data.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-080731 | Apr 2019 | JP | national |
This application is a national phase entry of PCT Application No. PCT/JP2020/015639, filed on Apr. 7, 2020, which claims priority to Japanese Application No. 2019-080731, filed on Apr. 22, 2019, which applications are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/015639 | 4/7/2020 | WO | 00 |
