History-Based Memory Controller Row Access Prediction
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Solution Overview
Problem
Conventional memory systems face delays due to activation and precharge times when predicting row hits or misses after a command queue becomes empty, as they either always close or always keep rows open, leading to inefficiencies depending on whether the same or different rows are accessed.
Innovation Solution
A history-based memory control system and method that predicts row hits or misses by determining access patterns, allowing an open row to remain open for hits and close for misses, thereby reducing delay times by adjusting the memory controller's mode based on previous access history.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory controller always closes the open row when the command queue becomes empty, then the precharge operation is performed to prepare bit lines for future accesses, but this causes activation delay when the same row is accessed again (row hit)
Solution Approach 1:
The memory controller dynamically switches between first mode (always close) and second mode (always open) based on predicted row access patterns. This dynamic adaptation allows the system to optimize between precharge readiness and activation speed depending on whether row hits or row misses are more likely to occur next
Solution Approach 2:
The system uses historical access pattern data to predict future row access behavior and adjusts the memory controller mode accordingly. This feedback mechanism enables the controller to learn from past accesses and make informed decisions about whether to maintain rows open or close them when the command queue is empty
2Loss of time
If the memory controller always keeps the open row open when the command queue becomes empty, then the activation delay is avoided for row hits, but this causes precharge delay when a different row is accessed (row miss)
Solution Approach 1:
The memory controller dynamically switches between first mode (always close) and second mode (always open) based on predicted row access patterns. This dynamic adaptation allows the system to optimize between precharge readiness and activation speed depending on whether row hits or row misses are more likely to occur next
Solution Approach 2:
The system performs preliminary prediction of row access patterns using historical data before the command queue becomes empty. This preliminary action allows the controller to proactively set the appropriate mode (open or close) in advance, avoiding both activation delays and precharge delays
3Device complexity
If conventional memory systems use always close or always open schemes, then the control logic is simple, but the system cannot adapt to varying access patterns leading to increased delay times
Solution Approach 1:
The memory controller transitions from static control schemes (always close or always open) to dynamic mode switching based on predicted access patterns. The controller maintains two operational modes and switches between them based on historical data analysis, enabling adaptation to varying access patterns while managing complexity through a finite state approach
Solution Approach 2:
The memory controller autonomously predicts row access patterns using its own historical access data and automatically adjusts its operating mode without external intervention. This self-service capability allows the system to adapt to access patterns independently, reducing delay times through intelligent self-optimization
Data Source
AI summary
A memory controller uses a history of the rows accessed by commands from a command queue in a command queue circuit to predict whether a second access performed immediately after the command queue becomes empty will be to a same row as a first access performed immediately before the command queue became empty. When the second access is predicted to be to a different row, the row corresponding to the first access is closed in response to the command queue becoming empty. When the second access is predicted to be to the same row, the row corresponding to the first access is not closed in response to the command queue becoming empty.