PCIe Flit Routing for SoC Agent Communication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional communication methods in systems-on-a-chip (SoC) with multiple processor cores face inefficiencies due to increased routing overhead and inflexibility, particularly with mesh interconnects and PCIe protocols, which are not suited for agent-to-agent communication, leading to high latency and inadequate communication rates.
Innovation Solution
Implementing a PCIe-based communication method where data blocks are transmitted as payloads within packets with PCIe compliant headers, using flits that are not strictly compliant with PCIe protocol requirements, allowing for efficient routing and re-initiation of communication pathways, while maintaining latency and flexibility requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mesh interconnect with packet forwarding is used for agent-to-agent communication, then communication can be established between processor cores, but routing overhead increases and communication efficiency deteriorates after more than a few instances of packet forwarding
Solution Approach 1:
The patent introduces a PCIe interface as an intermediary communication path between agents on the fabric. Instead of using the mesh interconnect with multiple packet forwarding hops, data is encapsulated in PCIe packets and transmitted through the PCIe physical layer, which acts as a mediator to bypass the inefficient mesh routing path.
Solution Approach 2:
The patent segments the communication path into two distinct parts: the fabric interface using flits for routing information, and the PCIe physical layer for direct data transmission. This segmentation allows each part to optimize for its specific function, with PCIe handling the bulk data transfer efficiently without mesh routing overhead.
2Speed
If PCIe protocol is used for agent-to-agent communication, then direct and fast communication is achieved, but the overhead and inflexibility of PCIe messages make it ill-suited for fabric communication
Solution Approach 1:
The patent merges the advantages of PCIe physical layer (fast direct transmission) with the flexibility of flit-based routing. By combining PCIe packet structure with flit payloads, the system achieves both high speed and routing adaptability, as flits can carry routing information while PCIe provides the fast physical transmission medium.
Solution Approach 2:
The patent applies different protocol characteristics to different parts of the communication system: PCIe protocol characteristics (fast direct transmission) are applied to the physical layer, while flit-based routing characteristics (flexibility and adaptability) are applied to the data payload. This local quality assignment allows each part to excel at its specific function.
3Reliability
If conventional PCIe messages are used for data transmission, then PCIe compliant communication is achieved, but the inflexibility and overhead make it inadequate for low latency agent-to-agent communication
Solution Approach 1:
The patent extracts only the essential PCIe physical layer characteristics (packet structure, physical transmission) while removing the inflexible PCIe message protocol requirements. By taking out only what is necessary for reliable transmission and discarding the overhead-heavy message structure, the system achieves PCIe compliance at the physical level without the latency penalties of full PCIe protocol compliance.
Data Source
AI summary
A system-on-a-chip (SoC) with one or more processors and other system components may have one or more peripheral component interconnect express (PCIe) physical connections between the processors and other system components to provide agent-to-agent communication. The agents on the communication fabric of the SoC may transmit data through the hardware PCIe interface where a transmitter device of an agent or digital logic component receives at least one data block for transmission and receives a flag corresponding to the at least one data block. The transmitter device may then send, via a PCIe physical layer, the received data blocks as a payload of a packet based on the flag, where the packet has a PCIe compliant header. The payload of the packet with the PCIe header may be entirely composed of these data blocks or flits from the agent.