Packet Processing Device Collective DMA Transfer
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Solution Overview
Problem
Existing packet processing systems face challenges in achieving high transmission performance due to increased hardware complexity and processor load when restoring combined packets, leading to bottlenecks in both reception and transmission processes.
Innovation Solution
A packet processing apparatus that includes a combination packet transfer unit capable of performing collective DMA transfer or collective writing, where information about the number of packets and data sizes is written to descriptors, allowing for efficient separation and transmission of packets without the need for extensive hardware or software-based restoration processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If collective DMA transfer or collective writing is implemented to improve transmission performance, then packet processing efficiency is improved, but hardware complexity increases due to the need for packet restoration functionality
Solution Approach 1:
The patent extracts the packet restoration functionality from the transmission path hardware and relocates it to the reception path, where it can be implemented using existing software-based processing. This allows collective DMA transfer to be implemented without adding complex hardware restoration capabilities in the transmission direction.
Solution Approach 2:
Instead of restoring packets at the transmission end (where collective transfer originates), the patent inverts the approach by restoring packets at the reception end after collective DMA transfer. This inversion eliminates the need for complex transmission-side restoration hardware while maintaining processing efficiency.
2Device complexity
If software-based packet restoration is used to reduce hardware complexity, then device complexity is reduced, but processor load increases
Solution Approach 1:
The patent introduces an intermediary mechanism where descriptor information serves as metadata that guides the software restoration process. By pre-configuring descriptors with packet boundary information during the collective transfer setup, the processor can efficiently restore packets without extensive analysis of the transferred data stream.
3Speed
If collective transfer is implemented to improve transmission speed, then packet transmission speed is improved, but the scale of hardware for packet restoration increases
Solution Approach 1:
The patent uses descriptor copies as metadata structures that contain packet restoration information. Instead of implementing complex hardware logic to analyze and restore packets, the system copies pre-prepared descriptor information through the collective transfer process, allowing software to efficiently reconstruct original packets using this metadata.
Data Source
AI summary
The packet processing apparatus includes a packet memory, a transmission processing unit that writes a plurality of packets to be transmitted to the packet memory to generate a combination packet into which the plurality of packets have been concatenated, a line handling unit that sends packets to a communication line, and a combination packet transfer unit that DMA-transfers the combination packet from the packet memory to the line handling unit. The transmission processing unit writes information on an address in the packet memory of beginning data of an individual packet in the combination packet to a descriptor. The line handling unit separates the DMA-transferred combination packet into a plurality of packets and sends the plurality of packets to the communication line.