Row Hammer Refresh Reduction via Memory Region Segmentation
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Solution Overview
Problem
Memory devices face challenges in reducing the frequency of row hammer refresh operations, which can lead to data corruption and increased power consumption due to adjacent word lines being affected by repeatedly activated aggressor rows.
Innovation Solution
Segmenting memory devices into regions using the least significant bits of the row address, allowing for masking of victim word lines to prevent unnecessary refresh operations, thereby reducing the number of row hammer refreshes and conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed on all rows to prevent data corruption, then data reliability is improved, but power consumption increases
Solution Approach 1:
The memory array is divided into multiple banks, and each bank is further divided into segments based on least significant address bits. This segmentation allows selective refreshing of only those segments that are vulnerable to row hammer effects, rather than refreshing the entire memory array, thus reducing power consumption while maintaining data reliability.
Solution Approach 2:
Different refresh strategies are applied to different segments of the memory array. Segments identified as victim rows (adjacent to aggressor rows) receive enhanced refresh protection, while other segments use normal refresh procedures. This localized approach ensures data reliability where needed without unnecessarily consuming power in unaffected areas.
2Reliability
If refresh operations are performed frequently to protect victim rows from row hammer effects, then data corruption is reduced, but the number of refresh operations increases
Solution Approach 1:
The system performs preliminary identification of aggressor rows and their adjacent victim rows before row hammer corruption occurs. By pre-marking these vulnerable segments and configuring masking indicators in advance, the system can quickly determine which rows need protection without performing frequent comprehensive refresh operations, thus reducing the overall refresh frequency while maintaining data integrity.
Solution Approach 2:
The system monitors access patterns to identify aggressor rows and uses this feedback to dynamically adjust refresh operations. When an aggressor row is detected, the system activates masking indicators for adjacent victim rows to trigger targeted refresh operations. This feedback-based approach ensures data integrity is maintained only when and where needed, reducing unnecessary refresh operations.
3Use of energy by moving object
If masking is applied to victim word lines to reduce refresh operations, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The masking mechanism is implemented by segmenting the memory address space using least significant bits (LSBs) of row addresses. This natural segmentation aligns with the physical bank structure and requires minimal additional control logic. The masking indicators are stored in simple lookup tables indexed by segment identifiers, avoiding complex control circuits while achieving effective victim row protection.
Solution Approach 2:
The masking system uses the existing address decoding logic and bank structure to automatically identify victim rows. When a row access occurs, the address bits themselves are used to determine the segment and check masking indicators, eliminating the need for separate complex control mechanisms. The system essentially uses its own address structure to drive the masking decision, reducing overall device complexity.
Data Source
AI summary
Methods, systems, and devices for techniques for reducing row hammer refresh are described. A memory device may be segmented into regions based on bits (e.g., the least significant bits) of row addresses such that consecutive word lines belong to different regions. A memory device may initiate a refresh operation for a first row of memory cells corresponding to a first word line. The memory device may determine that the first row is an aggressor row of a row hammer attack and may determine an adjacent row associated with a second word line as a victim row that may need to be refreshed (e.g., to counteract potential data corruption due to a row hammer attack). The memory die may determine whether to perform a row-hammer refresh operation on the victim row based on whether the victim row belongs to a region that is masked.