Dynamic Buffer Memory Allocation for SSD Read Operations
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Solution Overview
Problem
Flash memory devices have limited buffer memory capacity, leading to low map hit ratios due to fixed data and map area sizes, which hampers efficient data storage and retrieval, especially during read operations.
Innovation Solution
A semiconductor storage device with a controller that dynamically allocates memory space between a data area and a map area based on usage rates, increasing the map area during random read operations and the data area during sequential read operations to optimize storage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the buffer memory is divided into fixed data area and map area, then the buffer memory capacity is limited and manageable, but the map hit ratio is low during random read operations
Solution Approach 1:
The patent applies dynamics by making the buffer memory allocation flexible and adaptive. The controller dynamically adjusts the size of data area and map area based on the type of read operation (sequential or random). During random read operations, the map area is enlarged to improve map hit ratio, while during sequential read operations, the data area is enlarged to maximize buffer utilization. This dynamic reallocation resolves the contradiction between fixed capacity management and adaptive performance optimization.
2Reliability
If the map area size is increased to improve map hit ratio, then random read performance is improved, but the data area size is reduced
Solution Approach 1:
The patent implements dynamic reallocation of buffer memory between map area and data area based on operation type. During random read operations, the map area is temporarily enlarged at the expense of data area to improve map hit ratio. During sequential read operations, the allocation is reversed with data area enlarged to maximize buffering capacity. This time-varying allocation strategy resolves the contradiction by allowing both areas to be sufficiently large when needed, just not simultaneously at maximum size.
3Productivity
If the data area size is increased to store more user data, then sequential read performance is improved, but the map area size is reduced
Solution Approach 1:
The patent applies dynamic allocation by adjusting the relative sizes of data area and map area according to the read operation type. When sequential read operations are detected, the data area is enlarged to store more user data and improve throughput, while the map area is reduced. When random read operations are detected, the allocation is reversed. This dynamic switching resolves the contradiction between data area capacity and map area capacity, allowing each to be optimized for its specific operation type.
4Productivity
If the buffer memory capacity is fixed, then the device complexity is reduced, but the operational performance varies across different read operation modes
Solution Approach 1:
The patent implements a dynamic buffer memory allocation mechanism that adjusts data area and map area sizes based on read operation type. The controller monitors whether read operations are sequential or random and automatically reallocates buffer memory accordingly. This adds control complexity but significantly improves operational performance across different read modes, resolving the contradiction between fixed simplicity and adaptive performance.
Solution Approach 2:
The patent changes the parameters of buffer memory allocation (data area size and map area size) based on operation type. The controller modifies these parameters dynamically: during random reads, map area size is increased; during sequential reads, data area size is increased. This parameter adaptation allows the system to optimize performance for different operation modes while using the same physical buffer memory, resolving the contradiction between fixed capacity and variable performance requirements.
Data Source
AI summary
A method of operating a semiconductor storage device is provided. A memory space of a buffer memory is allocated into a data area for storing user data and a map area for storing map data. The user data and the map data are read from a nonvolatile memory. A size of the user data to be stored in the data are compared with a size of the data area. The size of the data area and the size of the map area are adaptively varied according to the comparison result.