PCIe Link Equalization Training Parameter Reuse

Solution Overview

Problem

The existing PCIe link equalization training process is lengthy, causing bus unavailability and potential system crashes or data corruption, especially when retraining is required outside the initial boot sequence, which can compromise system robustness and lead to errors or crashes.

Innovation Solution

The solution involves reusing optimal parameter coefficients from a previous successful equalization training cycle to reduce the time required for equalization training, allowing the system to bypass the time-intensive search for new optimal parameters and complete the training faster.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If equalization training is performed to ensure favorable bus bit error rate at higher speeds, then link reliability is improved, but link availability deteriorates due to lengthy training time

Engineering Contradiction:

Improvebus bit error rateVSAvoidequalization training time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs equalization training during the initial system boot sequence before the operating system loads, so that the link is already trained and available when needed. This preliminary action ensures that subsequent retraining events are minimized or eliminated, resolving the contradiction by preparing the link in advance rather than training it when data transmission is needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the timing parameter of equalization training from on-demand (when data needs to be transmitted) to upfront (during boot sequence). This parameter change transforms the training process from a reactive operation that causes downtime to a proactive operation that occurs when system resources are abundant, thus improving link availability while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If equalization retraining is performed outside initial boot sequence, then link adaptability is improved, but system robustness deteriorates due to operating system delays

Engineering Contradiction:

Improvelink retraining capabilityVSAvoidsystem robustness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs equalization training during the initial boot sequence before the operating system loads, so that the link is already trained and available when needed. This preliminary action ensures that subsequent retraining events are minimized or eliminated, resolving the contradiction by preparing the link in advance rather than training it when data transmission is needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system prevents the harmful effect of operating system delays by performing equalization training before the operating system is loaded. This preliminary anti-action counteracts the potential robustness issues that would arise from retraining during OS operation, allowing the system to maintain both adaptability and robustness.

Inventive Principle:

Principle #9Preliminary anti-action

3Speed

If PCIe link equalization training is performed at higher speeds, then communication speed is improved, but training time increases causing bus unavailability

Engineering Contradiction:

Improveinterconnect link speedVSAvoidtraining interval

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The system performs equalization training during the initial system boot sequence before the operating system loads, so that the link is already trained and available when needed. This preliminary action ensures that subsequent retraining events are minimized or eliminated, resolving the contradiction by preparing the link in advance rather than training it when data transmission is needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the timing parameter of equalization training from on-demand (when data needs to be transmitted) to upfront (during boot sequence). This parameter change transforms the training process from a reactive operation that causes downtime to a proactive operation that occurs when system resources are abundant, thus improving link availability while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9847891B2System and method for detecting reuse of an existing known high-speed serial interconnect link

Publication Date: 2017.12.19 NVIDIA CORP

AI summary

In a system according to one embodiment of the present disclosure, the system comprises a first device, a second device, a communications link, and a memory. The memory stores instructions that when executed by the system perform a method of communications link training. This method comprises requesting a speed change to a second speed for the first device communicating with the second device at a first speed via the communications link. A saved set of parameters are accessed for at least one of the first device and the second device. A first training cycle is performed for the first device and the second device at the second speed using the saved set of parameters for the at least one of the first device and second device. The reuse of parameters from a previous successful equalization training cycle reduces the time required to perform equalization training.