Memory Controller Hibernation Time Calculation
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Solution Overview
Problem
Conventional memory systems face challenges in accurately calculating system time during hibernation states, leading to potential inaccuracies in power management and performance optimization, especially when frequently switching between active and hibernation states, which can affect the lifespan and reliability of non-volatile memory devices.
Innovation Solution
A memory system that calculates an average hibernation time interval and system time based on absolute times received from a host, using an elapsed time calculator and flash translation layer (FTL) to monitor usage and perform garbage collection operations, ensuring efficient power management and performance optimization within a guaranteed period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the memory system frequently switches between active and hibernation states, then power consumption is reduced, but the accuracy of system time calculation deteriorates
Solution Approach 1:
The system performs preliminary actions by calculating the average hibernation time interval during active states before entering hibernation. This pre-calculated average is then used to estimate time elapsed during hibernation, allowing the system to maintain accurate time tracking without continuous host intervention during low-power states.
Solution Approach 2:
The system uses feedback from absolute time stamps received from the host during state transitions to continuously refine and update the average hibernation time interval calculation. This feedback mechanism ensures the time estimation model adapts to actual hibernation patterns, improving accuracy over time.
2Reliability
If the memory system accurately tracks system time during hibernation, then power management is optimized, but the complexity of time calculation increases
Solution Approach 1:
The system changes the approach from tracking individual hibernation durations to using an averaged time parameter. By converting multiple specific time measurements into a single average hibernation time interval parameter, the system simplifies the calculation complexity while maintaining reliable power management through continuous use of this averaged parameter.
3Reliability
If the FTL performs frequent garbage collection operations, then memory reliability is improved, but the usage of energy increases
Solution Approach 1:
The FTL uses feedback from the elapsed time calculator to dynamically adjust garbage collection operations. By monitoring the calculated system time and comparing it against thresholds, the FTL can schedule garbage collection at optimal moments that balance reliability maintenance with energy conservation, avoiding unnecessary operations during low-usage periods.
Solution Approach 2:
The system implements periodic garbage collection operations synchronized with the calculated system time and hibernation cycles. Rather than continuous or random GC operations, the FTL performs periodic maintenance aligned with the memory system's operational rhythm, reducing overall energy consumption while maintaining reliability.
Data Source
AI summary
A controller controlling a memory device includes an elapsed time calculator receiving a plurality of absolute times from a host when a state of a memory system including the memory device is changed between an active state and an inactive state, the plurality of absolute times including first, second, and third absolute times, calculating an average hibernation time interval between the first and second absolute times, and calculating a system time based on the third absolute time and the average hibernation time interval. The controller further includes a flash translation layer calculating expected usage of the memory device during a monitoring time interval based on the system time, calculating excess usage based on actual usage of the memory device during the monitoring time interval and the expected usage, and controlling the memory device to program data in a single level cell mode until the excess usage is fully consumed.