Memory Controller DSM Handling for Large-Range Deallocation
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Solution Overview
Problem
The long DSM response time for deallocation of large-size logical ranges in solid-state drives (SSDs) leads to increased read/write input/output latency for hosts, impacting performance.
Innovation Solution
A handling scheme that divides large-size logical ranges into aligned and unaligned deallocation zones, allowing for immediate response to the host while background processing of aligned zones is completed, thereby reducing DSM response time and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the memory controller processes deallocation of large-size logical ranges using traditional methods, then the deallocation operation is completed, but the DSM response time is prolonged and host I/O latency increases
Solution Approach 1:
The patent divides a deallocated logical range into multiple deallocation zones based on alignment with logical zones. Aligned zones (where the deallocation range exactly matches logical zone boundaries) are processed separately from unaligned zones (where the deallocation range does not match boundaries). This segmentation allows the controller to handle aligned zones through a faster DSM bitmap update path while processing unaligned zones through a more thorough L2P mapping table update path, thereby reducing overall DSM response time and minimizing impact on host I/O latency.
2Reliability
If the memory controller updates the L2P mapping table for all deallocated zones before responding, then data integrity is maintained, but the response time to the host is delayed
Solution Approach 1:
The patent performs preliminary classification of deallocation zones into aligned and unaligned categories before processing. For aligned zones, the controller updates the DSM bitmap in advance and can immediately send a response to the host, while the actual L2P mapping table updates for these zones are performed in the background. This preliminary action allows the system to maintain data integrity through proper tracking of deallocated zones while significantly reducing the response time to the host.
Data Source
AI summary
In certain aspects, a memory controller includes a data classification accelerator, a deallocation accelerator, and a mapping table accelerator. The data classification accelerator is configured to divide a deallocated logical range into a set of deallocation zones. The set of deallocation zones includes one or more first deallocation zones which are classified into one or more aligned zones, respectively. The deallocation accelerator is operatively coupled to the data classification accelerator, and configured to update a dataset management (DSM) bitmap based on the one or more aligned zones. The mapping table accelerator is operatively coupled to the data classification accelerator and the deallocation accelerator. The mapping table accelerator is configured to, responsive to the updating of the DSM bitmap, generate a response indicating that the deallocated logical range is processed.