Memory Device Alert Signal Test Mode for Row Hammer Mitigation
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Solution Overview
Problem
The interface between a memory device and a host lacks deterministic timing for alert signaling, which is crucial for effective row hammer mitigation, as the memory controller cannot accurately determine when a row hammer condition occurs, leading to potential data corruption and performance issues.
Innovation Solution
The implementation of an alert signal test mode allows the memory device to assert an alert signal with deterministic timing, enabling the memory controller to trigger refresh mitigation commands promptly by setting a register bit to enter the test mode and determining the delay for alert signal activation, thereby ensuring timely mitigation of row hammer conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the memory device uses internal alert signaling without test mode, then the device complexity is reduced, but the measurement precision of alert timing is insufficient
Solution Approach 1:
The patent implements a test mode that allows the memory device to preliminarily assert the alert signal in advance of actual row hammer conditions. This preliminary action enables the memory controller to measure and determine the exact timing of alert signal activation, resolving the measurement precision issue without requiring complex internal timing circuits in normal operation mode.
2Reliability
If the memory controller waits for alert signal without deterministic timing, then the loss of time is reduced, but the reliability of row hammer mitigation is insufficient
Solution Approach 1:
The patent establishes a feedback mechanism where the memory device asserts the alert signal with deterministic timing, and the memory controller uses this feedback to immediately trigger refresh mitigation commands. This feedback loop ensures reliable row hammer mitigation while minimizing time loss, as the controller knows exactly when the alert will be asserted and can prepare mitigation actions accordingly.
Data Source
AI summary
A system enables an alert signal test mode. The system has an alert signal line between the memory device and the memory controller. The memory device has a register that controls entry into the alert signal test mode. The memory controller sends a command to trigger the memory device to enter the alert signal test mode. In response to the commands, the memory device asserts the alert signal line with an alert signal in response to entry into the alert signal test mode.