Memory Calibration With Margin Checks Across Performance States
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Solution Overview
Problem
Memory calibration in subsystems consumes significant time, particularly in multi-rank systems and during frequency changes, impacting system performance and availability during real-time traffic.
Innovation Solution
Perform memory calibrations during initialization in various performance states, record differences between results, and use these differences to set parameters for new states without full recalibration, employing a margin check calibration at reduced points to verify validity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full horizontal calibration is performed during each performance state change, then sampling accuracy is ensured, but system unavailability time increases
Solution Approach 1:
The patent performs full horizontal calibration during initialization before performance state changes occur. The calibration results and difference information are stored in advance, so when a performance state change happens, the system can quickly apply pre-calculated parameters without performing a complete calibration again, thus reducing system unavailability time while maintaining sampling accuracy.
Solution Approach 2:
Instead of performing a complete horizontal calibration during every performance state change, the patent applies a simplified approach by only performing partial calibration or applying pre-stored difference information. This partial action is sufficient to maintain adequate sampling accuracy while significantly reducing the time the system remains unavailable.
2Measurement precision
If multiple calibrations are performed for different performance states, then calibration accuracy is improved, but calibration time and power consumption increase
Solution Approach 1:
The system performs comprehensive calibrations for multiple performance states during initialization and stores the results and difference information in advance. This preliminary action ensures that when performance states change, the system can quickly retrieve and apply appropriate calibration parameters without repeating time-consuming calibration processes, thus maintaining high calibration accuracy while reducing calibration time.
Solution Approach 2:
The patent utilizes difference information between calibration results of different performance states as stored parameters. When a performance state changes, the system adjusts calibration parameters based on these pre-calculated differences rather than performing complete recalibration, thereby maintaining calibration accuracy across different performance states while significantly reducing the time and power required for each state transition.
3Reliability
If comprehensive calibration is performed during initialization, then system reliability is improved, but initialization time increases
Solution Approach 1:
The patent performs comprehensive horizontal calibrations for all performance states during the initialization phase, storing both calibration results and difference information. This preliminary comprehensive action ensures high system reliability is established from the start, and subsequent performance state changes can quickly leverage these pre-computed parameters without requiring repeated comprehensive calibrations, thus balancing initialization time with ongoing system reliability.
Data Source
AI summary
Memory calibration with a margin check is disclosed. A memory subsystem includes a memory and a memory controller coupled to the memory. The memory controller includes a calibration circuit configured to perform, during an initialization process, horizontal memory calibrations for ones of a plurality of performance states and to determine and store, in a storage circuit, information indicative of a set of differences between calibration results for pairs of the plurality of performance states. The memory controller is further configured to, subsequent to the initialization process and in response to a change from a first one of the plurality of performance states to a second one of the plurality of performance states set initial memory parameters for the second performance state based on the set of differences. Thereafter, operation begins in the second performance state without performing an initial horizontal calibration.