Volatile Memory Row Hammer Data Preservation
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Solution Overview
Problem
Frequent access to a single row in memory can cause the row hammer effect, leading to data corruption in adjacent rows, with existing solutions either limiting access times or increasing refresh rates, resulting in additional issues.
Innovation Solution
A system and method that detects row-hammer indications by copying data from frequently accessed word lines to adjacent unused word lines, providing backup data that can be accessed when the original data becomes uncorrectable due to the row hammer effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is copied to backup word lines when row-hammer indication is detected, then data reliability is improved, but memory space is consumed
Solution Approach 1:
The patent applies the copying principle by creating backup copies of data from vulnerable word lines (adjacent to frequently accessed rows) to safe word lines. When row-hammer indication is detected, the system copies data from second and third word lines (adjacent to the hammered first word line) to fourth and fifth word lines (safe backup locations). This allows recovery of corrupted data from the backups, improving reliability while using additional memory space only when needed.
2Object-affected harmful factors
If access times to a row are limited in one refresh cycle, then row hammer effect is reduced, but productivity deteriorates
Solution Approach 1:
The patent applies preliminary action by proactively creating backup copies of data from word lines adjacent to frequently accessed rows before corruption occurs. The system detects row-hammer indications and performs preventive copying to safe word lines within the same refresh cycle, rather than waiting for corruption to happen. This allows normal access patterns to continue while maintaining backup copies for potential recovery.
3Reliability
If refresh rate of memory cell is increased, then data preservation is improved, but energy consumption increases
Solution Approach 1:
The patent applies local quality by applying protective measures selectively only to word lines that are adjacent to frequently accessed rows (second and third word lines next to first word line with row-hammer indication). Instead of increasing refresh rates for the entire memory array, the system targets specific vulnerable locations and creates backups only where needed. This localized approach preserves data in critical areas while minimizing energy consumption across the whole memory system.
Data Source
AI summary
Present disclosure includes a system for preserving data in a volatile memory and a method thereof. The volatile memory comprises a plurality of refreshing units, and each of the refreshing units comprises a plurality of word lines for storing data. The system comprises an accessing unit. The accessing unit is configured to detect a row-hammer indication indicating a first word line is frequently accessed, wherein the accessing unit is configured to copy data stored in the first word line to a second word line when the row-hammer indication is detected on the first word line, wherein the data stored in the first and the second word lines are available to be selectively accessed.