Virtual Channel Segmentation for Multi-Chip Traffic Isolation
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Solution Overview
Problem
In multi-chip systems, communication traffic between system-on-chips (SoCs) often experiences delays due to shared physical channels, where traffic types like PCIe and non-PCIe transactions interfere with each other, leading to performance degradation as buffers fill up and traffic flow is impacted.
Innovation Solution
Implementing virtual channels over physical channels to segregate traffic types, allowing individual management of each type's flow using separate buffers and credits, with each transaction associated with a specific traffic type and routed accordingly, preventing interference between different transaction types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple traffic types share a single physical channel, then device complexity is reduced, but traffic delays and performance degradation occur due to interference between different transaction types
Solution Approach 1:
The patent segments the single physical channel into multiple virtual channels, each dedicated to specific traffic types (e.g., PCIe transactions, non-PCIe transactions). This segmentation allows different traffic types to be transmitted simultaneously over the same physical medium without interfering with each other, thereby reducing traffic delays while maintaining a relatively simple physical channel structure.
2Productivity
If separate buffers are allocated for each traffic type, then traffic flow management is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal buffer management approach where multiple virtual channels share a common buffer pool with credit-based flow control. Instead of allocating separate physical buffers for each traffic type, the system uses a unified buffer structure that can dynamically serve different virtual channels based on their respective credit availability and traffic demands, thereby improving traffic flow management without proportionally increasing device complexity.
3Reliability
If virtual channels are implemented over physical channels, then traffic interference is reduced, but device complexity increases due to additional management overhead
Solution Approach 1:
The patent changes the organizational parameter of channel management from physical to virtual by introducing virtual channel identifiers and credit-based flow control parameters. This allows the system to achieve reliable traffic separation through software or firmware-controlled parameter management rather than requiring complex hardware isolation mechanisms, thereby improving traffic separation reliability while keeping the additional management overhead relatively minimal.
Data Source
AI summary
Systems and methods are provided to differentiate different types of traffic going through the same physical channel such that the traffic flow for different traffic types does not impact each other. The physical channel can be configured to support a plurality of virtual channels. Each transaction that needs to be communicated through the physical channel can be classified into a certain traffic type, and each traffic type can be assigned to a virtual channel. Each transaction can be communicated on a respective virtual channel based on the corresponding traffic type. If the traffic flow through a first virtual channel for a transaction slows down, the traffic flow through a second virtual channel for another transaction can continue without getting impacted by the slow down on the first virtual channel.