Flash Memory Read Timing and Cache Binding
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Solution Overview
Problem
Flash memory devices face reduced performance due to read access time and poor utilization of random cache read operations, as they must wait for data retrieval and are inefficient in handling host read commands.
Innovation Solution
Implementing a method and storage device that determines the timing of next host read commands to initiate random cache read or burst read operations, binding multiple read requests together to reduce read access time and improve efficiency by interleaving sense and transfer phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a page read operation is used to retrieve data from flash memory, then data can be accessed from the flash memory device, but the device must wait for the read access time (tR) which reduces performance
Solution Approach 1:
The controller initiates read operations to the flash memory die in advance before the host actually needs the data. By predicting when the host will issue read commands and pre-fetching data during idle periods or low-utilization times, the system prepares data ahead of time so that when the host requests it, the data is already available or nearly available, thereby hiding the read access time penalty.
Solution Approach 2:
The controller maintains continuous read operations to the flash memory die by keeping a pipeline of read commands outstanding. Instead of waiting idle for host commands, the controller continuously issues read requests to flash memory, ensuring that the flash device is always engaged in useful work and that data is being transferred continuously, maximizing utilization and amortizing the read access time across multiple operations.
2Productivity
If random cache read operations are used to hide read access time, then performance can be improved, but poor utilization occurs due to random rate of host commands
Solution Approach 1:
The controller monitors host command patterns and flash memory status to dynamically adjust its read operation strategy. By observing when the host issues commands and what data is being accessed, the controller adapts its pre-fetching and caching behavior to match actual host needs, improving both utilization efficiency and performance by avoiding unnecessary read operations.
Solution Approach 2:
The controller dynamically adjusts the rate and timing of read operations to the flash memory die based on current system conditions. Rather than using a fixed random cache read pattern, the controller modulates the read operation rate to match host demand patterns, optimizing the balance between hiding read access time and maintaining good utilization efficiency under varying workloads.
Data Source
AI summary
Embodiments of the present disclosure generally relate to a storage device and method of managing flash memory read operations of a storage device. In one embodiment, a method of retrieving information stored in a storage device comprises determining a timing of a next host read command for a flash memory die. If there is a storage device initiated read request for the flash memory die is determined. In response to an identification of the storage device initiated read request, a random cache read operation is initiated with the storage device initiated read request bound with the next host read command.