Memory System Pre-fetching Pattern Detection
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Solution Overview
Problem
Existing memory systems face inefficiencies in pre-fetching techniques due to the resetting of pattern detection processes by write-alike commands and the repeated pre-fetching and flushing of data caused by a high ratio of hibernate commands, leading to reduced performance and increased latency.
Innovation Solution
The memory system stores sequential read command data and maintains pattern detection even after receiving write-alike commands, allowing it to determine if subsequent read commands continue a sequential pattern. Additionally, it tracks the ratio of hibernate commands to other commands and refrains from pre-fetching if the ratio exceeds a threshold, thereby mitigating redundant pre-fetching procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pattern detection is reset by write-alike commands, then the memory system can respond to diverse command types, but sequential pattern detection accuracy deteriorates
Solution Approach 1:
The command stream is segmented into read command sequences and write-alike commands. The pattern detection mechanism is applied specifically to read command sequences, while write-alike commands are handled separately without triggering pattern detection reset, thus maintaining segmentation between pattern analysis and general command processing
Solution Approach 2:
Different quality requirements are applied to different command types: read commands undergo strict sequential pattern detection with continuous monitoring, while write-alike commands receive localized handling that does not interfere with the pattern detection state, allowing each command type to be processed with appropriate scrutiny
2Speed
If pre-fetching is performed frequently to reduce latency, then read access speed improves, but processing overhead increases due to redundant pre-fetching from hibernate commands
Solution Approach 1:
The system implements feedback through hibernate command tracking that monitors the ratio of hibernate commands to total commands. When this ratio exceeds a threshold, the system adjusts pre-fetching behavior accordingly, creating a feedback loop that prevents redundant pre-fetching operations while maintaining efficient read access speed
Solution Approach 2:
The pre-fetching strategy is made dynamic by adjusting its activation based on the hibernate command ratio. The system transitions between aggressive pre-fetching (when hibernate ratio is low) and conservative pre-fetching (when hibernate ratio is high), allowing optimal performance adaptation to varying workload characteristics
3Measurement precision
If pattern detection continues after write-alike commands, then sequential pattern detection accuracy improves, but system complexity increases
Solution Approach 1:
The pattern detection logic is extracted from the general command processing flow and implemented as a separate, dedicated mechanism that continuously monitors read commands independently of write-alike command handling. This extraction allows pattern detection to maintain its state without being interfered with by other command types, reducing the complexity of coordinating multiple processing streams
Data Source
AI summary
Methods, systems, and devices supporting techniques for pre-fetching information using pattern detection are described. Some memory systems may support pre-fetching information, such as logical-to-physical (L2P) mapping tables, data, or both, if a sequential pattern of read commands is detected. In some examples, the memory system may store a list of logical addresses indicated by received read commands and may determine whether the list corresponds to a sequential pattern independent of intervening write-alike commands. The list may store previous logical addresses for read commands, allowing the memory system to determine whether subsequent read commands form a sequential pattern. Additionally or alternatively, the memory system may track a ratio of hibernate commands to other commands (e.g., sequential read commands) and may refrain from pre-fetching L2P mapping tables for a detected sequence if the tracked ratio satisfies (e.g., exceeds) a threshold ratio.