Memory Controller RFM Command Frequency Control
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Solution Overview
Problem
The uniform issuance of Refresh Management (RFM) commands in DRAM systems based on a fixed threshold can lead to unnecessary transmissions, reducing the efficiency of bandwidth and performance in memory systems.
Innovation Solution
A memory system that includes a memory device with a notification circuit and a memory controller capable of varying the transmission frequency of RFM commands based on notifications about row hammer risks and temperature information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RFM commands are uniformly issued based on a fixed threshold, then row hammer refresh operations are performed regularly, but unnecessary transmissions occur reducing bandwidth efficiency and memory system performance
Solution Approach 1:
The patent applies dynamics by making the RFM command transmission frequency variable rather than fixed. The memory controller dynamically adjusts the transmission frequency based on real-time notification information from the memory device, including row hammer risk levels and temperature conditions. This allows the system to issue RFM commands more frequently when risks are high and less frequently when risks are low, thereby improving bandwidth efficiency while maintaining row hammer protection reliability.
Solution Approach 2:
The patent implements feedback through a notification circuit in the memory device that provides real-time information about row hammer risk and temperature to the memory controller. This feedback mechanism enables the controller to make informed decisions about RFM command transmission timing, adjusting the transmission frequency based on actual device conditions rather than following a fixed schedule, thus resolving the contradiction between reliable protection and bandwidth efficiency.
2Reliability
If RFM commands are transmitted frequently to ensure row hammer protection, then memory device reliability improves, but bandwidth efficiency and system performance deteriorate due to unnecessary transmissions
Solution Approach 1:
The system dynamically adjusts RFM command transmission frequency based on real-time notifications from the memory device. When the notification indicates low row hammer risk or acceptable temperature conditions, the controller reduces transmission frequency, thereby conserving bandwidth energy. When risks escalate, transmission frequency increases automatically, ensuring protection without wasting energy during low-risk periods.
Solution Approach 2:
The notification circuit provides continuous feedback about row hammer risk and temperature status, enabling the memory controller to optimize RFM command transmission timing. This feedback-driven approach ensures that bandwidth energy is consumed only when necessary for protection, eliminating wasteful transmissions during low-risk periods while maintaining reliable memory device protection when risks are present.
3Ease of manufacture
If a fixed threshold approach is used for RFM command issuance, then implementation is simple, but the system cannot adapt to varying memory device conditions leading to reduced efficiency
Solution Approach 1:
The patent transitions from a static fixed-threshold approach to a dynamic condition-based approach. The memory controller adapts RFM command transmission frequency based on real-time notifications about row hammer risk and temperature conditions. This dynamic adaptation maintains implementation feasibility while significantly improving versatility and efficiency by responding to actual device states rather than relying on predetermined fixed thresholds.
Solution Approach 2:
The notification circuit establishes a feedback loop that enables the system to adapt to varying memory device conditions. The controller receives continuous information about row hammer risk and temperature, allowing it to adjust RFM command transmission timing accordingly. This feedback mechanism preserves implementation simplicity while achieving high adaptability to different operational conditions.
Data Source
AI summary
Disclosed is a memory system which includes a memory device that includes a memory cell array and a notification circuit, and a memory controller that transmits a refresh management (RFM) command to the memory device, based on a number of occurrences of bank activation of a bank included in the memory cell array reaching a threshold. The memory controller controls a transmission frequency of the RFM command, based on a notification obtained through the notification circuit. The notification includes at least one of a row hammer risk for rows included in the bank or temperature information including a temperature range of the memory device.