Flash Memory Controller Write Command Merging
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Solution Overview
Problem
Existing memory devices face inefficiencies in data access due to repeated writing of overlapping logical address ranges and frequent clearing of data in flash memory pages, leading to performance degradation.
Innovation Solution
A data access method that stores commands in a queue, identifies overlapping logical address ranges, and combines write commands without intervening read commands to send combined write data to the memory, reducing redundant writes and clearing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the controller sequentially sends write commands to the memory without combining them, then the controller can process all write commands, but overlapping segments are repeatedly written to and system resources are used inefficiently
Solution Approach 1:
The controller combines multiple write commands with overlapping logical address ranges into a single write operation. When the controller detects overlapping address ranges in the command queue, it merges the data writes to these overlapping regions into one unified write operation, eliminating redundant write cycles and improving system resource utilization efficiency.
2Productivity
If the controller writes data to overlapping pages without combining commands, then all write commands are executed, but additional time is spent removing previously stored data causing processing delays
Solution Approach 1:
The controller merges write commands targeting overlapping pages into a single combined write operation. By combining these commands before execution, the controller eliminates the need to clear previously stored data from overlapping pages, as the combined write operation naturally overwrites the data in a single pass, thereby reducing data clearing time and improving write command execution rate.
Solution Approach 2:
The controller performs preliminary analysis of write commands in the queue to identify overlapping address ranges before execution. By detecting and combining overlapping write commands in advance, the controller prepares a unified write operation that avoids subsequent data clearing steps, thus reducing processing delays and improving execution rate.
3Reliability
If the controller repeatedly clears data in flash memory pages for small frequent writes, then data integrity is maintained, but processing delays increase and performance degrades
Solution Approach 1:
The controller combines multiple small write commands targeting the same flash memory page into a single aggregated write operation. This merging approach maintains data integrity by ensuring the page is written with the final correct data in one operation, while eliminating repeated clear operations that would otherwise be necessary for each individual small write, thus improving processing speed without sacrificing reliability.
4Device complexity
If the controller processes write commands individually without combination, then command processing is simple, but redundant writes occur and performance is degraded
Solution Approach 1:
The controller implements a command combination mechanism that merges write commands with overlapping logical address ranges into unified write operations. This approach increases device complexity by adding combination logic and address range analysis capabilities, but simultaneously improves memory device performance by eliminating redundant writes and reducing the total number of write operations required.
Data Source
AI summary
The invention provides a data access method. First, a plurality of commands received from a host is stored in a command queue. A plurality of logical address ranges of the commands is then calculated. A plurality of write commands is then selected from the commands, wherein the logical address ranges of the write commands are overlapping with each other. Whether at least one read command having a receiving order that is in between the receiving orders of the write commands exists in the command queue is then determined. When the at least one read command does not exist, write data corresponding to the write commands are combined together to obtain combined write data according to the logical address ranges of the write commands. A combined write command and the combined write data are then sent to a memory to request that the memory executes the write commands.