PCIe Retry Buffer Segmentation for Real-Time Data
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Solution Overview
Problem
The existing PCIe interface requires a large retry buffer capacity for real-time data transfer, leading to increased costs due to the need for storing and retransmitting data packets, especially for audio or video data, which is inefficient and inconvenient for users.
Innovation Solution
A method for real-time transfer over a PCIe interface that involves a link device receiving a retry command, determining the type of packet to be resent, and deciding whether to retransmit the packet or send a subsequent packet, using a pending transmission data buffer, a retry buffer with a data buffer for dummy packets, and a packet transmission circuit to reduce the retry buffer size by sending dummy packets when data packets are not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the retry buffer capacity is increased to ensure reliable retransmission of data packets, then the reliability of real-time transfer is improved, but the device cost increases significantly
Solution Approach 1:
The patent segments the retry buffer into two distinct parts: a command packet buffer for storing command packets and a data packet buffer for storing data packets. This segmentation allows the system to apply different buffering strategies to different packet types, reducing the overall buffer capacity needed while maintaining reliability for both command and data retransmissions.
Solution Approach 2:
The patent implements partial action by not requiring full retransmission of all data packets. Instead, it selectively retransmits only the necessary portions using a hybrid approach that combines TLP (Transaction Layer Packet) retransmission for commands and data packet retransmission for data, avoiding unnecessary buffer capacity allocation.
2Productivity
If the retry buffer capacity is increased to store more data packets for continuous transmission, then the productivity of real-time transfer is improved, but the device cost increases greatly
Solution Approach 1:
The patent divides the buffering function into separate command and data buffers, allowing the system to optimize each buffer independently. The command buffer ensures proper sequencing and retransmission of control packets, while the data buffer handles actual data payload, enabling continuous transmission without requiring excessive total buffer capacity.
Solution Approach 2:
The system performs preliminary actions by pre-processing and categorizing packets into command and data types before transmission. This allows the retry mechanism to be prepared in advance with appropriate buffer allocations, enabling continuous high-speed transmission without needing large buffers to handle unexpected retransmission needs.
3Adaptability or versatility
If the retry buffer is designed with large capacity to buffer M data packets, then the adaptability of the system to handle retransmission requests is improved, but the ease of manufacture decreases due to high cost
Solution Approach 1:
The patent segments the retry buffer into command and data portions, allowing the system to adapt to different retransmission scenarios with smaller, more manageable buffer allocations. This segmentation makes the system adaptable to various packet types while reducing the overall buffer capacity needed, thereby lowering manufacturing costs.
Solution Approach 2:
The patent changes the buffer capacity parameters by allocating different sizes to command and data buffers based on their specific retransmission requirements. This parameter optimization allows the system to maintain high adaptability for handling various retransmission requests while using minimal total buffer capacity, improving ease of manufacture.
Data Source
AI summary
A method capable of reducing a required capacity of a retry buffer of a link device when the link device transfers real-time data to a link partner through the PCIe interface determines how to resend a packet required by the link partner according to the type of the packet. When the packet is a data packet, the method determines if a pending data packet exists in a pending transmission data buffer. When the pending data packet exists in the pending transmission data buffer, the link device directly transmits the pending data packet to the link partner. When the pending data packet does not exist in the pending transmission data buffer, the link device transmits a dummy packet to the link partner. In this way, the retry buffer only requires enough capacity to store the dummy packet and buffer the command data packets.