Prefetch Table Storage Circuitry with Multi-State Stream Indicators
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Solution Overview
Problem
Existing data processing systems face challenges in accurately predicting data access patterns due to out-of-order execution and execution pipelining, leading to inefficient prefetching and misidentification of streaming data patterns.
Innovation Solution
A prefetch table with entries that include access count indicators and stream distance indicators having more than two states, along with stream direction indicators, to maintain accurate detection of streaming data patterns even in the presence of out-of-order execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional binary stream distance indicators are used in prefetch tables, then the device complexity is reduced, but the measurement precision of stream pattern detection deteriorates
Solution Approach 1:
The patent transitions from binary (two-state) stream distance indicators to multi-state indicators with more than two states, adding dimensional granularity to the prefetch table structure. This enables differentiation of multiple stream distance levels (e.g., L1, L2, L3 cache distances) rather than treating all non-root entries uniformly, thereby improving stream pattern detection accuracy without excessive complexity increase
Solution Approach 2:
The patent changes the parameter state of stream distance indicators from binary (0 or 1) to multi-state (0, 1, 2, or more states representing different distance levels). This parameter transformation allows the prefetch table to capture more nuanced streaming access patterns while maintaining a relatively simple table structure that can be implemented with standard memory circuitry
2Productivity
If out-of-order execution and pipelining are implemented to improve processing throughput, then productivity increases, but the reliability of data access pattern prediction deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the multi-state stream distance indicators continuously track and record actual streaming access patterns that occur during out-of-order execution. By monitoring real access behavior and updating distance states accordingly, the system adapts to dynamic execution patterns, maintaining reliable prefetch predictions even when instruction reordering occurs
Solution Approach 2:
The patent makes the prefetch table dynamic by allowing stream distance indicators to change states based on observed access patterns. Rather than using static binary values, the multi-state indicators can be updated to reflect changing stream distances caused by out-of-order execution, enabling the system to adapt to dynamic runtime behavior while maintaining prediction accuracy
Data Source
AI summary
Briefly, example apparatuses, articles of manufacture, and/or techniques are disclosed that may be implemented, in whole or in part, to implement, facilitate and/or support prefetching by a computing element, such as, prefetch table storage circuitry to store stream distance indicators corresponding to memory address regions.