Memory Interface Latency Signaling for Read-Miss Prevention
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Solution Overview
Problem
Memory systems face challenges in managing latency discrepancies between host expectations and actual memory device performance, particularly with non-volatile memory arrays, leading to inefficiencies and potential system crashes due to unexpected read-misses and buffer space issues.
Innovation Solution
An interface controller determines and communicates latency indications to the host through designated pins, using time delays or wait signals to manage read-misses and buffer space availability, ensuring the host observes appropriate delays before issuing subsequent commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the memory system uses non-volatile memory arrays with larger capacity, then storage capacity is improved, but latency variations and read-misses increase causing system crashes
Solution Approach 1:
The interface controller determines and communicates latency indications to the host before the host issues subsequent access commands. This preliminary action allows the host to anticipate latency variations and adjust its command timing accordingly, preventing system crashes while maintaining the benefits of non-volatile memory arrays with larger capacity
Solution Approach 2:
The system implements a feedback mechanism where the interface controller monitors buffer space availability and latency conditions, then communicates this information back to the host via latency indications. The host uses this feedback to dynamically adjust its access pattern, improving system reliability while maintaining high capacity operation
2Productivity
If the host issues access commands at higher speed, then productivity is improved, but latency mismatches increase causing unexpected read-misses
Solution Approach 1:
The system dynamically adjusts the host's command timing based on current latency conditions. The interface controller provides latency indications that enable the host to adapt its command issuance rate in real-time, allowing high productivity when latency is low while preventing read-misses when latency increases, thus maintaining reliability at high speeds
3Reliability
If the interface controller implements latency indication mechanism, then system reliability is improved, but device complexity increases
Solution Approach 1:
The interface controller utilizes existing command pins and communication channels to convey latency indications, rather than requiring entirely new dedicated signaling paths. This multi-functionality approach improves reliability through latency management while minimizing the increase in device complexity by repurposing existing infrastructure
Data Source
AI summary
Methods, systems, and devices for a latency indication in a memory system or sub-system are described. An interface controller of a memory system may transmit an indication of a time delay (e.g., a wait signal) to a host in response to receiving an access command from the host. The interface controller may transmit such an indication when a latency associated with performing the access command is likely to be greater than a latency anticipated by the host. The interface controller may determine a time delay based on a status of buffer or a status of memory device, or both. The interface controller may use a pin designated and configured to transmit a command or control information to the host when transmitting a signal including an indication of a time delay. The interface controller may use a quantity, duration, or pattern of pulses to indicate a duration of a time delay.