Memory Controller Polarity Inversion for SRAM Usefulness Indicators
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Solution Overview
Problem
In processor-based systems, the usefulness indicators in SRAM banks become less effective over time due to uniformity, leading to challenges in recalibrating them without incurring additional SRAM or register overhead, which can impact system performance.
Innovation Solution
A global polarity indicator is introduced, allowing the memory controller to interpret and update usefulness indicators in a variable manner, either directly or inversely correlating with their usefulness, enabling selective replacement and recalibration without additional memory resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional recalibration methods (shifting, flash-clearing, or clearing bits) are used to maintain usefulness indicator effectiveness, then the differentiation among usefulness indicators is restored, but multiple memory table entries must be written within a very short period which is impracticable for SRAM devices
Solution Approach 1:
The patent inverts the conventional recalibration approach by using a read-only counter stored in each memory table entry to track the number of times the entry has been replaced. Instead of writing multiple entries to reset usefulness indicators, the system reads the counter value and uses it to determine whether recalibration is needed, thereby avoiding the impracticable mass write operation while still restoring differentiation among usefulness indicators.
Solution Approach 2:
The patent introduces a counter as an intermediary element stored within each memory table entry. This counter mediates between the usefulness indicator and the recalibration process by providing a record of replacement frequency that can be read without requiring additional write operations. The counter serves as a proxy for tracking entry age and usefulness without directly manipulating the usefulness indicator through costly write operations.
2Productivity
If usefulness indicators are stored within separate additional SRAM or registers to enable frequent recalibration, then recalibration can be performed without impacting system performance, but additional processor chip area and power consumption are required
Solution Approach 1:
The patent merges the counter functionality with the existing memory table entry structure by storing the counter within the same SRAM bank that holds the memory table entries. Instead of using separate additional SRAM or registers, the counter is integrated into the existing entry format, thereby eliminating the need for additional processor chip area while still enabling efficient tracking of replacement frequency for recalibration purposes.
Solution Approach 2:
The patent makes the memory table entry structure multi-functional by having each entry simultaneously store the usefulness indicator, the counter for tracking replacements, and the actual memory data. This universal entry structure eliminates the need for dedicated separate storage resources for recalibration tracking, thereby reducing processor chip area and power consumption while maintaining the capability for frequent recalibration operations.
3Productivity
If usefulness indicators are stored within separate additional SRAM or registers to enable frequent recalibration, then recalibration can be performed without impacting system performance, but additional power consumption is required
Solution Approach 1:
The patent merges the counter functionality with the existing memory table entry structure by storing the counter within the same SRAM bank that holds the memory table entries. Instead of using separate additional SRAM or registers, the counter is integrated into the existing entry format, thereby eliminating the need for additional processor chip area while still enabling efficient tracking of replacement frequency for recalibration purposes.
Solution Approach 2:
The memory table entry itself serves the dual purpose of storing both the usefulness indicator and the replacement counter. The entry is self-sufficient in tracking its own replacement history without requiring external dedicated storage resources. This self-service approach reduces the overall power consumption of the system by eliminating redundant storage structures and their associated power requirements.
Data Source
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AI summary
Providing variable interpretation of usefulness indicators for memory tables in processor-based systems is disclosed. In one aspect, a memory system comprises a memory table providing multiple memory table entries, each including a usefulness indicator. A memory controller of the memory system comprises a global polarity indicator representing how the usefulness indicator for each memory table entry is interpreted and updated by the memory controller. If the global polarity indicator is set, the memory controller interprets a value of each usefulness indicator as directly corresponding to the usefulness of the corresponding memory table entry. Conversely, if the global polarity indicator is not set, the polarity is reversed such that the memory controller interprets the usefulness indicator value as inversely corresponding to the usefulness of the corresponding memory table entry. In this manner, the interpretation and updating of usefulness indicators by the memory controller can be varied using the global polarity indicator.