Link Interface Idle Flit Filtering for Ordered CRC Reporting
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Solution Overview
Problem
Conventional link interfaces, such as those employing OpenCAPI, face inefficiencies in maintaining link continuity due to the need for continuous transmission of idle flits of varying sizes, which can disrupt CRC error reporting and lead to unnecessary retransmissions of control and data flits, resulting in bandwidth loss.
Innovation Solution
The implementation of a link interface with a physical layer that transmits and receives idle flits of two sizes, where the data link layer removes and filters short idle flits, ensuring CRC errors are reported in the correct order, utilizing a finite state machine and delay logic to manage the reporting of errors, thereby maintaining link continuity and reducing retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If idle flits of varying sizes are transmitted to maintain link continuity, then link continuity is maintained, but CRC error reporting becomes disrupted and retransmissions increase
Solution Approach 1:
The patent segments the handling of idle flits by size, creating separate processing paths for short idle flits (first size) and long idle flits (second size). The data link layer specifically filters and processes short idle flits separately from other flit types, allowing CRC error reporting to be managed independently for each category, thus preventing disruption to overall error reporting accuracy while maintaining link continuity.
Solution Approach 2:
The patent introduces an intermediary filtering mechanism at the data link layer that specifically targets short idle flits. This intermediary layer processes and filters short idle flits before they reach the CRC error reporting mechanism, acting as a buffer that prevents these varying-size idle flits from disrupting the error reporting sequence while still allowing link continuity to be maintained.
2Productivity
If short idle flits are filtered and CRC errors are reported in correct order, then retransmissions are reduced, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing specific filtering and processing rules only for short idle flits (first size) at the data link layer, rather than uniformly processing all flit types. This localized approach targets the specific problem area (short idle flit handling) with enhanced logic while leaving other flit processing relatively simple, thus improving bandwidth efficiency without uniformly increasing device complexity across all processing paths.
Data Source
AI summary
A link interface is provided of a communication protocol using idle flow control digits (flits) to maintain link continuity. The link interface includes: a physical layer of the communication protocol configured to transmit and receive flits via a link, wherein the communication protocol provides for idle flits of first and second sizes for maintaining link continuity, the first size being smaller than the second size; and a data link layer configured to transmit and receive flits to/from the physical layer. The data link layer is configured to remove idle flits of the first size received from the physical layer and to report cyclic redundancy check errors of filtered first sized idle flits in a correct order in relation to other flits.