BIOS Derating Table for Temperature-Based DFE Tap Updates
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Solution Overview
Problem
Information handling systems face increased complexity and delays in memory channel training due to high DDR speeds and the need for multiple trainings at different temperatures, leading to suboptimal decision feedback equalization (DFE) tap values.
Innovation Solution
Implementing a derating table in the BIOS to store DFE tap values and derating values corresponding to different temperatures, allowing for automatic updates of tap values during runtime temperature changes, thereby reducing the need for retraining and improving equalization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple trainings are performed at different temperatures to optimize DFE tap values, then equalization accuracy is improved, but training time and system complexity increase
Solution Approach 1:
The BIOS performs multiple temperature-based trainings during the initial power-on self-test phase to pre-determine optimal DFE tap values for different temperature ranges. These tap values are stored in a lookup table, allowing the runtime system to quickly retrieve and apply the appropriate values without performing time-consuming trainings when temperature changes occur.
Solution Approach 2:
The system dynamically selects DFE tap values from the lookup table based on the current temperature range. The memory controller monitors temperature changes and automatically switches between pre-determined tap values corresponding to different temperature ranges, enabling adaptive equalization without full retraining.
2Measurement precision
If multiple trainings are performed at different temperatures to optimize DFE tap values, then equalization accuracy is improved, but device complexity increases
Solution Approach 1:
The BIOS performs multiple temperature-based trainings during the initial power-on self-test phase to pre-determine optimal DFE tap values for different temperature ranges. These tap values are stored in a lookup table, allowing the runtime system to quickly retrieve and apply the appropriate values without performing time-consuming trainings when temperature changes occur.
Solution Approach 2:
A derating table (lookup table) is introduced as an intermediary data structure to store the relationship between temperature ranges and optimal DFE tap values. This table serves as a pre-computed reference that simplifies the runtime operation, eliminating the need for complex real-time training algorithms while maintaining equalization accuracy.
3Reliability
If full retraining is performed when temperature changes occur, then optimal equalization is maintained, but productivity and speed decrease
Solution Approach 1:
The system dynamically selects DFE tap values from the lookup table based on the current temperature range. The memory controller monitors temperature changes and automatically switches between pre-determined tap values corresponding to different temperature ranges, enabling adaptive equalization without full retraining.
Solution Approach 2:
Instead of performing time-consuming full training procedures when temperature changes occur, the system copies or retrieves pre-determined tap values from the lookup table that correspond to the current temperature range. This copying approach maintains equalization quality while avoiding the productivity loss associated with repeated full trainings.
Data Source
AI summary
An information handling system includes a memory subsystem and a basic/input out system (BIOS). The BIOS performs multiple trainings of the memory subsystem, and each of the trainings is performed at a different temperature. The BIOS stores multiple derating values in a derating table of the BIOS, and each of the derating values corresponds to a respective tap value at a respective temperature. During a subsequent power on self test of the information handling system, the BIOS performs a first training of the memory subsystem, and stores a first set of tap values. During a runtime of the information handling system, a memory controller determines whether a temperature of the information handling system has changed by a predetermined amount. In response to the temperature changing by the predetermined amount, the memory controller utilizes the derating values in the derating table to automatically update the tap values.