Memory Garbage Collection with Bitmap-Guided Selective L2P Lookup
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Solution Overview
Problem
Existing memory systems face inefficiencies in garbage collection due to the time-consuming and resource-intensive process of looking up Logical to Physical address (L2P) tables to identify valid data, especially when dealing with large amounts of random data, leading to prolonged garbage collection times and increased firmware overhead.
Innovation Solution
Implementing a memory system with a memory controller that utilizes different types of bitmaps (first and second bitmaps) to identify valid data, allowing for efficient garbage collection by directly determining physical addresses based on logical values, reducing the need for frequent L2P table lookups and optimizing the process for varying data randomness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If L2P table lookup is used to identify valid data during garbage collection, then accurate identification of valid data is achieved, but garbage collection time and firmware overhead increase significantly
Solution Approach 1:
The patent segments the identification process into two parts: a fast bitmap filter that quickly identifies candidate valid pages, and a more accurate L2P table lookup that is only performed on the reduced set of candidates. This segmentation reduces the overall time by avoiding full L2P lookups for all pages while maintaining identification accuracy through the two-stage verification process.
Solution Approach 2:
The patent performs preliminary action by maintaining and updating bitmaps that pre-indicate which pages are likely valid. During garbage collection, these pre-computed bitmaps provide an immediate first-pass identification of valid data locations, eliminating the need for time-consuming L2P table lookups for obviously valid pages and reducing the scope of subsequent verification steps.
2Reliability
If comprehensive L2P table lookups are performed to ensure data validity, then data integrity is maintained, but firmware overhead and processing resources increase
Solution Approach 1:
The patent applies partial action by performing L2P table lookups only when necessary - specifically, only for pages that are candidates after the bitmap filter stage or when verification is required for integrity. This selective approach maintains data integrity through targeted verification while reducing firmware overhead by avoiding redundant comprehensive lookups for all pages.
3Productivity
If traditional garbage collection methods are used, then storage space management is achieved, but write timeouts increase due to prolonged collection processes
Solution Approach 1:
The patent performs preliminary action by pre-computing and maintaining bitmaps that track valid data locations. During garbage collection, these pre-computed structures enable rapid identification of valid pages, significantly reducing the duration of the collection process. This speedup directly reduces write timeouts while maintaining effective storage space management through the same garbage collection functionality.
Data Source
AI summary
Examples disclose a memory system and operating method thereof and computer-readable storage medium. An example memory system includes a memory controller and a memory coupled to the memory controller. The memory includes multiple memory blocks, a memory block includes multiple physical pages. The memory controller is configured to: determine at least one source memory block from the multiple memory blocks; in response to the bitmap type associated with a first source memory block from the at least one source memory block being a first bitmap, write valid data stored in the first source memory block into the first target memory block from the multiple memory blocks; in response to the valid data being written into the first target memory block, erase the source memory block.